#if 0 /*
#/  ================================================================
#/
#/    bxgen.c
#/
#/  Binary executable code generation and linking.
#/  Compiler backend.
#/
#/  ----------------------------------------------------------------
#/
#/  Qualities
#/
#/  - Compiler backend in the form of a library
#/  - Single source file
#/  - Simple and flexible API
#/  - No external dependencies
#/  - No configuration required
#/  - No dynamic memory management
#/  - Easy cross-compilation
#/  - Platform-independent host
#/
#/  Inspirations
#/
#/  - tinycc  https://repo.or.cz/w/tinycc.git
#/  - Cuik    https://github.com/RealNeGate/Cuik
#/  - QBE     https://c9x.me/compile/
#/
#/  To-Do list
#/
#/  - Simplify
#/    - Factor out checks
#/    - Allow to format the message in CHECK and FAIL macros
#/  - Library
#/    - Terminal color option
#/    - Proper prefixes for identifiers
#/    - Effective entity allocation
#/    - Improve error handling
#/    - Memory reallocation when necessary
#/    - Multithreading
#/  - Codegen
#/    - Architectures
#/      - x86_64
#/      - i386
#/      - RISC-V
#/      - ARM
#/      - WebAssembly
#/    - Dump generated asm and binary
#/    - Implicit procedure prototypes
#/    - Evaluation
#/    - Static single-assignment
#/    - Sea of Nodes
#/    - Optimization layers
#/    - JIT
#/    - Debug info
#/    - Inlined assembly
#/    - C compiler and self-compilation
#/    - Meta codegen  >:3
#/  - Linker
#/    - Formats
#/      - ELF
#/      - COFF
#/      - PE
#/      - OMF
#/      - Mach-O
#/    - Linking with libc
#/    - Statically-linked executable
#/    - Object file
#/    - Static library
#/    - Dynamic-link library
#/    - Dynamically-linked executable
#/    - GNU ld script
#/    - GOT and PLT
#/    - Thread-local storage
#/    - Static libraries
#/    - Dynamic libraries
#/    - Unused dependencies elimination
#/  - Comprehensive test suite
#/  - Built-in standard library
#/    - Terminal
#/    - Graphics  >:3
#/    - Input devices  >:3
#/    - Math
#/    - Soft floating-point arithmeric
#/    - File I/O
#/    - Threads
#/    - Networking  >:3
#/    - Audio  >:3
#/
#/  Bugs
#/
#/  - Linking with libc doesn't work
#/
#/  Done features
#/
#/  - Simplify
#/    - Use 0 for UNDEFINED. Make the zero value useful
#/    - Chunk table for names and arrays
#/  - Library
#/    - IO static dispatch
#/    - Correct serialization for endianness
#/    - Proper error handling
#/  - Codegen
#/    - Implicit exit after ret from entry point
#/
#/  ----------------------------------------------------------------
#/
#/    (C) 2024 Mitya Selivanov <guattari.tech>
#/
#/  ================================================================
#/
#/    Self-compilation shell script
#/
SRC=${0##*./}
BIN=${SRC%.*}
gcc                                 \
  -Wall -Wextra -Werror -pedantic   \
  -Wno-old-style-declaration        \
  -Wno-missing-braces               \
  -Wno-unused-variable              \
  -Wno-unused-but-set-variable      \
  -Wno-unused-parameter             \
  -Wno-enum-compare                 \
  -O0                               \
  -fsanitize=undefined,address,leak \
  -o $BIN $SRC &&                   \
  ./$BIN $@ &&                      \
  rm $BIN
exit $? # */
#endif

//  ================================================================
//
//    Types
//
//  ================================================================

#ifndef TYPES_HEADER_GUARD_
#define TYPES_HEADER_GUARD_

typedef signed char        i8;
typedef signed short       i16;
typedef signed             i32;
typedef signed long long   i64;
typedef unsigned char      u8;
typedef unsigned short     u16;
typedef unsigned           u32;
typedef unsigned long long u64;
typedef char               c8;
typedef int                c32;
typedef signed char        b8;
typedef float              f32;
typedef double             f64;

#endif // TYPES_HEADER_GUARD_

//  ================================================================
//
//    IR data declarations
//
//  ================================================================

#ifndef BXGEN_HEADER_GUARD_
#define BXGEN_HEADER_GUARD_

enum {
  //  Log level
  ERROR = 1,
  WARNING,
  INFO,
  VERBOSE,
  TRACE,

  //  Limits
  //

  CHUNK_TABLE_ALIGNMENT = 16,

  POOL_CAPACITY   = 10 * 1024 * 1024,
  MAX_STRING_SIZE =      1024 * 1024,

  //  For indices
  UNDEFINED = 0,

  //  Sea of Nodes flow type
  //

  FLOW_DATA = 0,
  FLOW_CONTROL,

  //  Semantic node operations
  //

  OP_NONE = 0,
  OP_PTR,
  OP_I8,
  OP_I16,
  OP_I32,
  OP_I64,
  OP_F32,
  OP_F64,
  OP_ADD,
  OP_SUB,
  OR_NEG,
  OP_UMUL,
  OP_IMUL,
  OP_UDIV,
  OP_IDIV,
  OP_AND,
  OP_OR,
  OP_XOR,
  OP_NOT,
  OP_IF,
  OP_ADDRESS,
  OP_CALL,
  OP_RET,

  //  Calling conventions

  CONV_UNKNOWN = 0,
  CONV_CDECL,
  CONV_STDCALL,
  CONV_FASTCALL,
  CONV_THISCALL,

  //  Unit types
  //

  UNIT_CODE = 0,
  UNIT_LIBRARY_OBJECT,
  UNIT_LIBRARY_STATIC,
  UNIT_LIBRARY_DYNAMIC,

  //  Entity types
  //

  ENTITY_NODE = 0,
  ENTITY_PROC,
  ENTITY_UNIT,

  //  IO dispatch operations
  //

  IO_OPEN_READ = 0,
  IO_OPEN_WRITE,
  IO_CLOSE,
  IO_SEEK,
  IO_TELL,
  IO_READ,
  IO_WRITE,
  IO_CHMOD_EXE,

  IO_SEEK_CURSOR = 0,
  IO_SEEK_BEGIN,
  IO_SEEK_END,

  //  Formats
  //

  FORMAT_UNKNOWN = 0,
  FORMAT_ELF,
  FORMAT_COFF,
  FORMAT_PE,
  FORMAT_OMF,
  FORMAT_MATCH_O,

  //  Architecture
  //

  ARCH_UNKNOWN = 0,
  ARCH_RISC_V,
  ARCH_I386,
  ARCH_X86_64,
  ARCH_ARM32,
  ARCH_ARM64,

  //  Relocations
  //

  REL_ADD_INSTRUCTION_ADDRESS,
  REL_ADD_RO_OP_ADDRESS,
  REL_ADD_PROC_ADDRESS,
};

typedef struct {
  i64 size;
  i64 offset;
} Chunk_Handle;

typedef i64 Var;

typedef struct {
  Var condition;
} If;

typedef struct {
  Chunk_Handle vals;
} Ret;

typedef struct {
  //  NOTE
  //  We may call a local procedure by it's id,
  //  or a global procedure by name.

  u16          convention; // can be implicitly retrieved from the procedure
  i64          target_proc;
  Chunk_Handle target_name;
  Chunk_Handle args;
} Call;

//  A semantic node is an operation with optional data
//  and possible references to other nodes.

typedef struct {
  u16 op;
  i64 index_in_proc;
  union {
    Chunk_Handle lit;
    Var          ref;
    struct {
      i64 ctrl_previous;
      i64 ctrl_index;
      union {
        If   if_;
        Ret  ret;
        Call call;
        Var  bin_op[2];
      };
    };
  };
} Node;

//  A procedure is a collection of semantic nodes
//  and has a string name.

typedef struct {
  u16          convention;
  Chunk_Handle name;
  Chunk_Handle nodes;
  i64          ret_index;
  i64          unit;
  i64          index_in_unit;
} Proc;

//  A compilation unit is a collection of procedures.
//

typedef struct {
  u16          type;
  i64          entry_point_index;
  Chunk_Handle name;
  Chunk_Handle procs;
  Chunk_Handle links;
} Unit;

//  An entity can be any of:
//  - Node
//  - Proc
//  - Unit
//
//  Every entity can be referenced by it's unique index
//  in the entity pool.

typedef struct {
  b8  is_enabled;
  u16 type;
  union {
    Node node;
    Proc proc;
    Unit unit;
  };
} Entity;

//  Pool, a collection of all entities.
//
//    NOTE
//    We use one single large memory block for *everything*.

typedef struct {
  i64          size;
  i64          capacity;
  u8 *         data;
  Chunk_Handle entities;
} Pool;

typedef struct {
  b8  emit_done;
  i64 offset;
  i64 reg;
  u64 occupied_reg;
} Codegen_Entity;

typedef struct {
  u16 type;
  i64 offset;
  i64 size;
  i64 value;
  i64 name_size;
  c8 *name;
  i64 proc;
} Codegen_Rel_Entry;

typedef struct {
  i64 offset;
  i64 address;
} Link_Sec_Entry;

typedef struct {
  i64 name_size;
  c8 *name;
  i64 address;
  i64 size;
  i64 got_offset;
  i64 obj_index;
  i64 sec_index;
} Link_Sym_Entry;

typedef struct {
  i64 symbol;
} Link_Rel_Entry;

typedef struct {
  b8           has_entry;
  i64          entry_point;
  i64          offset_code;
  i64          offset_ro_data;
  Chunk_Handle entities;
  Chunk_Handle rels;
  Chunk_Handle buffer_code;
  Chunk_Handle buffer_ro_data;
} Codegen_Context;

typedef struct {
  i64 num_obj_files;

  Chunk_Handle obj_file_buffer;
  Chunk_Handle dependencies_buffer;
  Chunk_Handle obj_file_offsets;
  Chunk_Handle sections;
  Chunk_Handle symbols;
  Chunk_Handle rels;
  Chunk_Handle output_buffer;
} Linker_Context;

//  ================================================================
//
//    API declarations
//
//  ================================================================
//
//  Hooks
//
//    NOTE
//    Shoud be implemented on the user side.
//    See: `* Helper procedures`
//
//  ================================================================

#ifdef __cplusplus
extern "C" {
#endif

void dispatch_assert(b8 condition, c8 *message, u32 line, c8 *file);
void dispatch_log   (i32 log_level, u32 line, c8 *file, c8 *format, ...);
void dispatch_io    (u16 op, i64 *id, i64 *size, void *data, void *user_data);

//  ================================================================
//
//  Main API
//
//  ================================================================

i64  pool_add   (Pool *pool, Entity data);
void pool_remove(Pool *pool, i64 entity, u16 type);

i64  node_init   (Pool *pool, Node data);
void node_destroy(Pool *pool, i64 node);

i64  node_data_reference(Pool *pool, i64 node);
i64  node_data_array_c8 (Pool *pool, i64 size, c8 *data);
i64  node_data_ptr      (Pool *pool, u64 address);
i64  node_data_i32      (Pool *pool, i32 value);
i64  node_data_i64      (Pool *pool, i64 value);
i64  node_data_add      (Pool *pool, Var x, Var y);
i64  node_data_sub      (Pool *pool, Var x, Var y);

i64  node_ctrl_call        (Pool *pool, i64 previous, i64 index, i64 target_proc, i64 num_args, Var *args);
i64  node_ctrl_call_by_name(Pool *pool, i64 previous, i64 index, i64 name_size, c8 *name, i64 num_args, Var *args);
i64  node_ctrl_if          (Pool *pool, i64 previous, i64 index, Var condition);
i64  node_ctrl_ret         (Pool *pool, i64 previous, i64 index, i64 num_values, Var *values);

i64  proc_initi         (Pool *pool);
void proc_destroy       (Pool *pool, i64 proc);
void proc_set_convention(Pool *pool, i64 proc, u16 convention);
void proc_set_name      (Pool *pool, i64 proc, i64 name_size, c8 *name);
void proc_node_add      (Pool *pool, i64 proc, i64 node);
void proc_node_remove   (Pool *pool, i64 proc, i64 node);

i64  unit_init           (Pool *pool, u16 type);
void unit_destroy        (Pool *pool, i64 unit);
void unit_proc_add       (Pool *pool, i64 unit, i64 proc);
void unit_proc_remove    (Pool *pool, i64 unit, i64 proc);
void unit_link_add       (Pool *pool, i64 unit, i64 link_unit);
void unit_link_remove    (Pool *pool, i64 unit, i64 link_unit);
void unit_set_name       (Pool *pool, i64 unit, i64 name_size, c8 *name);
void unit_set_entry_point(Pool *pool, i64 unit, i64 entry_point_proc);
i64  unit_write_in_memory(Pool *pool, Codegen_Context *codegen, Linker_Context *linker, i64 unit, u16 format, u16 arch);
b8   unit_write          (Pool *pool, i64 unit, u16 format, u16 arch, i64 io_id, void *io_user_data);

i64  io_open_read (i64 name_size, c8 *name, void *user_data);
i64  io_open_write(i64 name_size, c8 *name, void *user_data);
void io_close     (i64 f, void *user_data);
b8   io_seek      (i64 f, i64 offset, u16 origin, void *user_data);
i64  io_tell      (i64 f, void *user_data);
i64  io_read      (i64 f, i64 size, void *data, void *user_data);
i64  io_write     (i64 f, i64 size, void *data, void *user_data);
void io_chmod_exe (i64 f, void *user_data);

//  ================================================================
//
//  Helpers API
//
//  ================================================================

#ifndef DISABLE_HELPERS

i64  n_ref(i64 proc, i64 node);
i64  n_ptr(i64 proc, u64 address);
i64  n_str(i64 proc, c8 *value);
i64  n_i32(i64 proc, i32 value);
i64  n_i64(i64 proc, i64 value);
i64  n_add(i64 proc, Var x, Var y);
i64  n_sub(i64 proc, Var x, Var y);

i64  n_call        (i64 proc, i64 ctrl_previous, i64 ctrl_index, i64 target_proc, i64 num_args, Var *args);
i64  n_call_by_name(i64 proc, i64 ctrl_previous, i64 ctrl_index, c8 *name, i64 num_args, Var *args);
i64  n_if          (i64 proc, i64 ctrl_previous, i64 ctrl_index, Var condition);
i64  n_ret         (i64 proc, i64 ctrl_previous, i64 ctrl_index, i64 num_vals, Var *vals);

i64  p_new(i64 unit, c8 *name);
i64  p_new_entry(i64 unit);
void p_add(i64 proc, i64 node);

i64  u_new(void);
void u_add(i64 unit, i64 proc);
void u_entry_point(i64 unit, i64 proc);
void u_elf_x86_64(i64 unit, c8 *output_file_name);

void l_code(i64 unit, i64 link_unit);
void l_object(i64 unit, c8 *object_library);
void l_static(i64 unit, c8 *static_library);
c8 * l_find(c8 *name, b8 silent);

#define ARGS(...)                                  \
  (sizeof((Var[]) { __VA_ARGS__ }) / sizeof(Var)), \
  (Var[]) { __VA_ARGS__ }
#define N_CALL(proc, prev_, index_, target_proc, ...)  n_call        ((proc), (prev_), (index_), (target_proc), ARGS(__VA_ARGS__))
#define N_CALL_BY_NAME(proc, prev_, index_, name, ...) n_call_by_name((proc), (prev_), (index_), (name), ARGS(__VA_ARGS__))
#define N_RET(proc, prev_, index_, ...)                n_ret         ((proc), (prev_), (index_), ARGS(__VA_ARGS__))

#endif

#ifdef __cplusplus
}
#endif

#endif // BXGEN_HEADER_GUARD_

//  ================================================================
//
//    IMPLEMENTATION
//
//  ================================================================
//
//    Compilation options
//
//  ================================================================

#ifndef BXGEN_HEADER
#ifndef BXGEN_IMPL_GUARD_
#define BXGEN_IMPL_GUARD_

#ifdef __cplusplus
#error Implementation code should be compiled with a C compiler!
#endif

#ifndef HELPERS
#define HELPERS 1
#endif

#ifndef TESTING
#define TESTING 1
#endif

#ifndef LOG_LEVEL
#define LOG_LEVEL 5
#endif

#ifndef LOG_BLOCKING
#define LOG_BLOCKING 0
#endif

#ifndef TRACE_BLOCKING
#define TRACE_BLOCKING 1
#endif

#define VERSION "dev"

//  ================================================================
//
//  * Basic utilities
//
//  ================================================================

#ifndef NULL
#define NULL ((void *) 0)
#endif

#ifdef NDEBUG
#  define CHECK(condition, error_string, fail_result)          \
    do {                                                       \
      b8 ok_ = (condition);                                    \
      if (!ok_) {                                              \
        dispatch_log(ERROR, __LINE__, __FILE__, error_string); \
        return fail_result;                                    \
      } \
    } while (0)
#else
#  define CHECK(condition, error_string, fail_result)         \
    do {                                                      \
      b8 ok_ = (condition);                                   \
      dispatch_assert(ok_, error_string, __LINE__, __FILE__); \
      if (!ok_)                                               \
        return fail_result;                                   \
    } while (0)
#endif

#ifdef NDEBUG
#  define LAX(condition, error_string)                           \
    do {                                                         \
      if (!(condition))                                          \
        dispatch_log(WARNING, __LINE__, __FILE__, error_string); \
    } while (0)
#else
#  define LAX(condition, error_string) \
    dispatch_assert((condition), error_string, __LINE__, __FILE__)
#endif

#ifdef NDEBUG
#  define FAIL(error_string, fail_result)                  \
    dispatch_log(ERROR, __LINE__, __FILE__, error_string); \
    return fail_result
#else
#  define FAIL(error_string, fail_result)                 \
    dispatch_assert(0, error_string, __LINE__, __FILE__); \
    return fail_result
#endif

#define LOG(log_level, ...)                                     \
  do {                                                          \
    if (log_level <= LOG_LEVEL)                                 \
      dispatch_log(log_level, __LINE__, __FILE__, __VA_ARGS__); \
  } while (0)

i64 align(i64 x, i64 a) {
  CHECK(a > 0, "Sanity", 0);
  return x + ((a - (x % a)) % a);
}

void mem_set(void *dst, u8 val, i64 size) {
  CHECK(dst != NULL, "Sanity",);
  CHECK(size > 0,    "Invalid size",);

  for (i64 i = 0; i < size; ++i)
    ((u8 *)dst)[i] = val;
}

void mem_cpy(void *dst, void *__restrict src, i64 size) {
  CHECK(dst != NULL, "Sanity",);
  CHECK(src != NULL, "Sanity",);
  CHECK(size >= 0,   "Invalid size",);

  for (i64 i = 0; i < size; ++i)
    ((u8 *)dst)[i] = ((u8 *)src)[i];
}

b8 mem_eq(void *a, void *b, i64 size) {
  CHECK(a != NULL, "Sanity", 0);
  CHECK(b != NULL, "Sanity", 0);
  CHECK(size > 0,  "Invalid size", 0);

  u8 *x = (u8 *) a;
  u8 *y = (u8 *) b;

  for (i64 i = 0; i < size; ++i)
    if (x[i] != y[i])
      return 0;

  return 1;
}

b8 str_eq(i64 a_len, c8 *a, i64 b_len, c8 *b) {
  return a_len == b_len && mem_eq(a, b, a_len);
}

#define STR_EQ(z, a, b) \
  (z == sizeof(b) - 1 && mem_eq((a), (b), sizeof(b) - 1))

i64 str_len(c8 *s, c8 *s_end) {
  CHECK(s < s_end, "Buffer overflow", 0);

  for (i64 len = 0; s + len < s_end; ++len)
    if (s[len] == '\0')
      return len;

  FAIL("Buffer overflow", 0);
}

i64 str_len_or(c8 *s, c8 *s_max, i64 or_val) {
  for (i64 len = 0; s + len < s_max; ++len)
    if (s[len] == '\0')
      return len;

  return or_val;
}

c8 *find_char(c8 *s, c8 *s_end, c8 c) {
  CHECK(s != NULL,     "Sanity", NULL);
  CHECK(s_end != NULL, "Sanity", NULL);

  while (s < s_end && *s != c)
    ++s;

  return *s == c ? s : NULL;
}

c8 *find_str(c8 *s, c8 *s_end, c8 *sub, c8 *sub_end) {
  CHECK(s != NULL,       "Sanity", NULL);
  CHECK(s_end != NULL,   "Sanity", NULL);
  CHECK(sub != NULL,     "Sanity", NULL);
  CHECK(sub_end != NULL, "Sanity", NULL);

  while (sub_end - sub <= s_end - s && s < s_end) {
    c8 *q = s;
    c8 *p = sub;
    for (; q < s_end && p < sub_end; ++q, ++p)
      if (*q != *p)
        break;
    if (p == sub_end)
      return s;
    ++s;
  }

  return NULL;
}

c8 *find_str_in_table(c8 *buf, c8 *buf_end, c8 *sub, c8 *sub_end) {
  CHECK(buf     != NULL, "Sanity", NULL);
  CHECK(buf_end != NULL, "Sanity", NULL);
  CHECK(sub     != NULL, "Sanity", NULL);
  CHECK(sub_end != NULL, "Sanity", NULL);

  while (buf < buf_end) {
    i64 len = str_len(buf, buf_end);
    if (str_eq(len, buf, sub_end - sub, sub))
      return buf;
    buf += len + 1;
  }

  return NULL;
}

u64 u64_from_dec_str(c8 *s, c8 *s_end) {
  CHECK(s != NULL && s_end != NULL, "Sanity", 0);
  CHECK(s < s_end,                  "Buffer overflow",   0);
  CHECK(*s >= '0' && *s <= '9',     "Parsing failed",    0);

  u64 x = 0;
  for (; s < s_end && *s >= '0' && *s <= '9'; ++s)
    x = (x * 10) + (*s - '0');

  LAX(s == s_end || *s == ' ' || *s == '\0', "Parsing failed");
  return x;
}

//  ================================================================
//
//  * Chunk table and entity pool
//
//  ================================================================

Chunk_Handle chunk_add(Pool *pool, i64 size, void *data) {
  CHECK(pool != NULL, "Sanity", (Chunk_Handle) {0});
  CHECK(size > 0,     "Sanity", (Chunk_Handle) {0});
  CHECK(data != NULL, "Sanity", (Chunk_Handle) {0});

  i64 chunk_size = align(size, CHUNK_TABLE_ALIGNMENT);

  CHECK(pool->size + chunk_size <= pool->capacity, "Out of memory", (Chunk_Handle) {0});

  Chunk_Handle h = {
    .size   = size,
    .offset = pool->size,
  };

  mem_cpy(pool->data + h.offset, data, size);

  pool->size += chunk_size;

  return h;
}

void chunk_remove(Pool *pool, Chunk_Handle h) {
  (void) pool;
  (void) h;
}

#ifdef __GNUC__
__attribute__ ((warn_unused_result))
#endif
Chunk_Handle chunk_resize(Pool *pool, Chunk_Handle h, i64 size) {
  CHECK(pool != NULL,                    "Sanity", (Chunk_Handle) {0});
  CHECK(size > 0,                        "Sanity", (Chunk_Handle) {0});
  CHECK(h.offset >= 0 && h.size >= 0,    "Sanity", (Chunk_Handle) {0});
  CHECK(h.offset + h.size <= pool->size, "Invalid handle",    (Chunk_Handle) {0});

  i64 chunk_size = align(size, CHUNK_TABLE_ALIGNMENT);
  i64 prev_size  = align(h.size, CHUNK_TABLE_ALIGNMENT);

  if (chunk_size <= prev_size)
    return (Chunk_Handle) {
      .size   = size,
      .offset = h.offset,
    };

  if (h.offset + h.size == pool->size) {
    CHECK(pool->size + chunk_size - h.size <= pool->capacity, "Out of memory", (Chunk_Handle) {0});

    pool->size += chunk_size - prev_size;

    return (Chunk_Handle) {
      .size   = size,
      .offset = h.offset,
    };
  }

  CHECK(pool->size + chunk_size <= pool->capacity, "Out of memory", (Chunk_Handle) {0});

  Chunk_Handle dst = {
    .size   = size,
    .offset = pool->size,
  };

  mem_cpy(pool->data + dst.offset, pool->data + h.offset, h.size);

  pool->size += chunk_size;

  return dst;
}

u8 *chunk(Pool *pool, Chunk_Handle h) {
  CHECK(pool != NULL,                    "Sanity", NULL);
  CHECK(h.offset >= 0 && h.size >= 0,    "Sanity", pool->data);
  CHECK(h.offset + h.size <= pool->size, "Invalid handle",    pool->data);

  if (h.size == 0)
    return pool->data;

  return pool->data + h.offset;
}

#define CHUNK(pool_, handle_, type_) ((type_ *) chunk((pool_), (handle_)))

b8 entity_enabled(Pool *pool, i64 id) {
  CHECK(pool != NULL, "Sanity", 0);
  CHECK(id != UNDEFINED, "Undefined", 0);
  CHECK(id > 0 && id < pool->entities.size / (i64) sizeof(Entity), "Invalid id", 0);
  Entity *entities = CHUNK(pool, pool->entities, Entity);
  CHECK(entities != NULL, "Internal", 0);
  return entities[id].is_enabled;
}

i64 pool_add(Pool *pool, Entity data) {
  CHECK(pool != NULL && pool->data != NULL, "Sanity", UNDEFINED);

  i64 num_entities = pool->entities.size / sizeof(Entity);
  if (num_entities == UNDEFINED)
    ++num_entities;

  i64 id          = num_entities++;
  data.is_enabled = 1;

  pool->entities = chunk_resize(pool, pool->entities, num_entities * sizeof(Entity));

  CHECK(id != UNDEFINED, "Undefined", UNDEFINED);
  CHECK(id < pool->entities.size / (i64) sizeof(Entity), "Buffer overflow", UNDEFINED);

  CHUNK(pool, pool->entities, Entity)[id] = data;

  return id;
}

void pool_remove(Pool *pool, i64 entity, u16 type) {
  CHECK(pool != NULL && pool->data != NULL, "Sanity",);

  i64 num_entities = pool->entities.size / sizeof(Entity);
  Entity *entities = CHUNK(pool, pool->entities, Entity);

  CHECK(entity > UNDEFINED,    "Undefined",);
  CHECK(entity < num_entities, "Buffer overflow",);

  CHECK(entities[entity].is_enabled,   "Entity already removed",);
  CHECK(entities[entity].type == type, "Invalid entity type",);

  entities[entity] = (Entity) {0};
}

//  ================================================================
//
//  * Semantic graph
//
//  ================================================================

Node *node_by_id(Pool *pool, i64 id) {
  CHECK(pool != NULL && pool->data != NULL, "Sanity", NULL);

  i64 num_entities = pool->entities.size / sizeof(Entity);
  Entity *entities = CHUNK(pool, pool->entities, Entity);

  CHECK(id != UNDEFINED,                     "Undefined",       &entities->node);
  CHECK(id > UNDEFINED && id < num_entities, "Buffer overflow", &entities->node);

  CHECK(entities[id].is_enabled,          "No node",             &entities->node);
  CHECK(entities[id].type == ENTITY_NODE, "Invalid entity type", &entities->node);

  return &entities[id].node;
}

Proc *proc_by_id(Pool *pool, i64 id) {
  CHECK(pool != NULL && pool->data != NULL, "Sanity", NULL);

  i64 num_entities = pool->entities.size / sizeof(Entity);
  Entity *entities = CHUNK(pool, pool->entities, Entity);

  CHECK(id != UNDEFINED,                     "Undefined",       &entities->proc);
  CHECK(id > UNDEFINED && id < num_entities, "Buffer overflow", &entities->proc);

  CHECK(entities[id].is_enabled,          "No proc",             &entities->proc);
  CHECK(entities[id].type == ENTITY_PROC, "Invalid entity type", &entities->proc);

  return &entities[id].proc;
}

Unit *unit_by_id(Pool *pool, i64 id) {
  CHECK(pool != NULL && pool->data != NULL, "Sanity", NULL);

  i64 num_entities = pool->entities.size / sizeof(Entity);
  Entity *entities = CHUNK(pool, pool->entities, Entity);

  CHECK(id != UNDEFINED,                     "Undefined",       &entities->unit);
  CHECK(id > UNDEFINED && id < num_entities, "Buffer overflow", &entities->unit);

  CHECK(entities[id].is_enabled,          "No unit",             &entities->unit);
  CHECK(entities[id].type == ENTITY_UNIT, "Invalid entity type", &entities->unit);

  return &entities[id].unit;
}

i64 node_init(Pool *pool, Node data) {
  data.index_in_proc = UNDEFINED;

  return pool_add(pool, (Entity) {
    .type = ENTITY_NODE,
    .node = data,
  });
}

void node_destroy(Pool *pool, i64 node) {
  //  TODO
  pool_remove(pool, node, ENTITY_NODE);
}

i64 node_data_reference(Pool *pool, i64 node) {
  return node_init(pool, (Node) {
    .op  = OP_ADDRESS,
    .ref = node,
  });
}

i64 node_data_array_c8(Pool *pool, i64 size, c8 *data) {
  return node_init(pool, (Node) {
    .op  = OP_I8,
    .lit = chunk_add(pool, size, data),
  });
}

i64 node_data_ptr(Pool *pool, u64 address) {
  return node_init(pool, (Node) {
    .op  = OP_PTR,
    .lit = chunk_add(pool, sizeof address, &address),
  });
}

i64 node_data_i32(Pool *pool, i32 value) {
  return node_init(pool, (Node) {
    .op  = OP_I32,
    .lit = chunk_add(pool, sizeof value, &value),
  });
}

i64 node_data_i64(Pool *pool, i64 value) {
  return node_init(pool, (Node) {
    .op  = OP_I64,
    .lit = chunk_add(pool, sizeof value, &value),
  });
}

i64 node_data_add(Pool *pool, Var x, Var y) {
  return node_init(pool, (Node) {
    .op     = OP_ADD,
    .bin_op = {
      x,
      y,
    },
  });
}

i64 node_data_sub(Pool *pool, Var x, Var y) {
  return node_init(pool, (Node) {
    .op     = OP_SUB,
    .bin_op = {
      x,
      y,
    },
  });
}

u16 resolve_calling_convention(Pool *pool, i64 proc) {
  Proc *p = proc_by_id(pool, proc);
  CHECK(p != NULL, "No proc", CONV_UNKNOWN);

  if (p->convention == CONV_UNKNOWN)
    p->convention = CONV_CDECL;

  return p->convention;
}

i64 node_ctrl_call(Pool *pool, i64 previous, i64 index, i64 target_proc, i64 num_args, Var *args) {
  return node_init(pool, (Node) {
    .op            = OP_CALL,
    .ctrl_previous = previous,
    .ctrl_index    = index,
    .call = {
      .convention  = resolve_calling_convention(pool, target_proc),
      .target_proc = target_proc,
      .args        = chunk_add(pool, num_args * sizeof *args, args),
    },
  });
}

i64 node_ctrl_call_by_name(Pool *pool, i64 previous, i64 index, i64 name_size, c8 *name, i64 num_args, Var *args) {
  return node_init(pool, (Node) {
    .op            = OP_CALL,
    .ctrl_previous = previous,
    .ctrl_index    = index,
    .call = {
      .convention  = CONV_CDECL,
      .target_proc = UNDEFINED,
      .target_name = chunk_add(pool, name_size, name),
      .args        = chunk_add(pool, num_args * sizeof *args, args),
    },
  });
}

i64 node_ctrl_if(Pool *pool, i64 previous, i64 index, Var condition) {
  return node_init(pool, (Node) {
    .op            = OP_IF,
    .ctrl_previous = previous,
    .ctrl_index    = index,
    .if_ = {
      .condition = condition,
    },
  });
}

i64 node_ctrl_ret(Pool *pool, i64 previous, i64 index, i64 num_values, Var *values) {
  return node_init(pool, (Node) {
    .op            = OP_RET,
    .ctrl_previous = previous,
    .ctrl_index    = index,
    .ret = {
      .vals = chunk_add(pool, num_values * sizeof *values, values),
    },
  });
}

i64 proc_init(Pool *pool) {
  return pool_add(pool, (Entity) {
    .type = ENTITY_PROC,
    .proc = (Proc) {
      .ret_index     = UNDEFINED,
      .index_in_unit = UNDEFINED,
    },
  });
}

void proc_destroy(Pool *pool, i64 proc) {
  //  TODO
  pool_remove(pool, proc, ENTITY_PROC);
}

void proc_set_convention(Pool *pool, i64 proc, u16 convention) {
  Proc *p = proc_by_id(pool, proc);
  CHECK(p != NULL, "No proc",);

  p->convention = convention;
}

void proc_set_name(Pool *pool, i64 proc, i64 name_size, c8 *name) {
  Proc *p = proc_by_id(pool, proc);
  CHECK(p != NULL, "No proc",);

  p->name = chunk_resize(pool, p->name, name_size);
  mem_cpy(chunk(pool, p->name), name, p->name.size);
}

void proc_node_add(Pool *pool, i64 proc, i64 node) {
  Proc *p = proc_by_id(pool, proc);
  Node *n = node_by_id(pool, node);

  CHECK(p != NULL, "No proc",);
  CHECK(n != NULL, "No node",);

  CHECK(n->index_in_proc == UNDEFINED, "Internal",);

  i64 num_nodes = p->nodes.size / sizeof(i64);

  if (num_nodes == UNDEFINED)
    ++num_nodes;

  i64 index = num_nodes++;

  if (n->op == OP_RET) {
    //  Only one return node is allowed.
    CHECK(p->ret_index == UNDEFINED, "Internal",);
    p->ret_index = index;
  }

  n->index_in_proc = index;

  p->nodes = chunk_resize(pool, p->nodes, num_nodes * sizeof(i64));

  CHECK(index != UNDEFINED, "Undefined",);
  CHECK(index < p->nodes.size / (i64) sizeof(i64), "Buffer overflow",);

  CHUNK(pool, p->nodes, i64)[index] = node;
}

void proc_node_remove(Pool *pool, i64 proc, i64 node) {
  Proc *p = proc_by_id(pool, proc);
  Node *n = node_by_id(pool, node);

  CHECK(p != NULL, "No proc",);
  CHECK(n != NULL, "No node",);

  i64 *nodes = CHUNK(pool, p->nodes, i64);

  CHECK(n->index_in_proc != UNDEFINED, "Undefined",);
  CHECK(n->index_in_proc < p->nodes.size / (i64) sizeof(i64), "Buffer overflow",);
  CHECK(nodes[n->index_in_proc] == node, "Internal",);

  if (n->op == OP_RET) {
    CHECK(p->ret_index != UNDEFINED, "Internal",);
    p->ret_index = UNDEFINED;
  }

  nodes[n->index_in_proc] = UNDEFINED;
  n->index_in_proc        = UNDEFINED;
}

i64 unit_init(Pool *pool, u16 type) {
  return pool_add(pool, (Entity) {
    .type = ENTITY_UNIT,
    .unit = (Unit) {
      .type              = type,
      .entry_point_index = UNDEFINED,
    }
  });
}

void unit_destroy(Pool *pool, i64 unit) {
  pool_remove(pool, unit, ENTITY_UNIT);
}

void unit_proc_add(Pool *pool, i64 unit, i64 proc) {
  Unit *u = unit_by_id(pool, unit);
  Proc *p = proc_by_id(pool, proc);

  CHECK(u != NULL, "No unit",);
  CHECK(p != NULL, "No proc",);

  CHECK(p->index_in_unit == UNDEFINED, "Internal",);

  i64 num_procs = u->procs.size / sizeof(i64);

  i64 *procs = CHUNK(pool, u->procs, i64);
  CHECK(procs != NULL, "Internal",);

  for (i64 i = 1; i < num_procs; ++i)
    if (procs[i] == proc)
      return;

  if (num_procs == UNDEFINED)
    ++num_procs;

  i64 index = num_procs++;

  p->index_in_unit = index;
  u->procs = chunk_resize(pool, u->procs, num_procs * sizeof(i64));

  CHECK(index != UNDEFINED, "Undefined",);
  CHECK(index < u->procs.size / (i64) sizeof(i64), "Buffer overflow",);

  CHUNK(pool, u->procs, i64)[index]  = proc;
}

void unit_proc_remove(Pool *pool, i64 unit, i64 proc) {
  Unit *u = unit_by_id(pool, unit);
  Proc *p = proc_by_id(pool, proc);

  CHECK(u != NULL, "No unit",);
  CHECK(p != NULL, "No proc",);

  i64 *procs = CHUNK(pool, u->procs, i64);

  CHECK(p->index_in_unit != UNDEFINED, "Undefined",);
  CHECK(p->index_in_unit < u->procs.size / (i64) sizeof(i64), "Buffer overflow",);
  CHECK(procs[p->index_in_unit] == proc, "Internal",);

  if (u->entry_point_index == p->index_in_unit)
    u->entry_point_index = UNDEFINED;

  procs[p->index_in_unit] = UNDEFINED;
  p->index_in_unit        = UNDEFINED;
}

void unit_link_add(Pool *pool, i64 unit, i64 link_unit) {
  Unit *u = unit_by_id(pool, unit);
  CHECK(u != NULL, "No unit",);

  i64 num_links = u->links.size / sizeof(i64);

  i64 *links = CHUNK(pool, u->links, i64);
  CHECK(links != NULL, "Internal",);

  for (i64 i = 1; i < num_links; ++i)
    if (links[i] == link_unit)
      return;

  if (num_links == UNDEFINED)
    ++num_links;

  i64 index = num_links++;

  u->links = chunk_resize(pool, u->links, num_links * sizeof(i64));

  CHECK(index != UNDEFINED, "Undefined",);
  CHECK(index < u->links.size / (i64) sizeof(i64), "Buffer overflow",);

  CHUNK(pool, u->links, i64)[index] = link_unit;
}

void unit_link_remove(Pool *pool, i64 unit, i64 link_unit) {
  Unit *u = unit_by_id(pool, unit);
  CHECK(u != NULL, "No unit",);

  i64  num_links = u->links.size / sizeof(i64);
  i64 *links     = CHUNK(pool, u->links, i64);

  for (i64 i = 1; i < num_links; ++i)
    if (links[i] == link_unit) {
      links[i] = UNDEFINED;
      return;
    }

  FAIL("Link not found",);
}

void unit_set_name(Pool *pool, i64 unit, i64 name_size, c8 *name) {
  Unit *u = unit_by_id(pool, unit);
  CHECK(u != NULL, "No unit",);

  u->name = chunk_resize(pool, u->name, name_size);
  CHECK(u->name.size == name_size, "Internal",);
  mem_cpy(CHUNK(pool, u->name, c8), name, u->name.size);
}

void unit_set_entry_point(Pool *pool, i64 unit, i64 entry_point_proc) {
  Unit *u = unit_by_id(pool, unit);
  CHECK(u != NULL, "No unit",);

  if (entry_point_proc == UNDEFINED) {
    u->entry_point_index = UNDEFINED;
    return;
  }

  Proc *p = proc_by_id(pool, entry_point_proc);
  CHECK(p != NULL, "No proc",);

  CHECK(p->index_in_unit != UNDEFINED, "Internal",);
  CHECK(p->index_in_unit < u->procs.size / (i64) sizeof(i64), "Buffer overflow",);
  CHECK(CHUNK(pool, u->procs, i64)[p->index_in_unit] == entry_point_proc, "Internal",);

  u->entry_point_index = p->index_in_unit;
}

//  ================================================================
//
//  * Serialization
//
//  ----------------------------------------------------------------
//
//  Terms
//
//  LE = little endian
//  BE = big endian
//  HO = host ordering
//
//  byte  = 8 bits
//  word  = 2 bytes
//  dword = 4 bytes
//  qword = 8 bytes
//
//  ================================================================

enum {
  BIT_LE         = 0,
  BIT_BE         = 1,
  BIT_ORDER_MASK = 1,

  BYTE_LE         = 0,
  BYTE_BE         = 2,
  BYTE_ORDER_MASK = 2,

  WORD_LE         = 0,
  WORD_BE         = 4,
  WORD_ORDER_MASK = 4,

  DWORD_LE         = 0,
  DWORD_BE         = 8,
  DWORD_ORDER_MASK = 8,

  F64_DWORD_LE         = 0,
  F64_DWORD_BE         = 16,
  F64_DWORD_ORDER_MASK = 16,

  LE = BIT_LE | BYTE_LE | WORD_LE | DWORD_LE | F64_DWORD_LE,
  BE = BIT_BE | BYTE_BE | WORD_BE | DWORD_BE | F64_DWORD_BE,
};

typedef struct {
  unsigned first:1;
} Bits;

u32 host_bit_order(void) {
  if ((*(Bits *) &(u8) { 1 }).first == 1)
    return BIT_LE;
  return BIT_BE;
}

u32 host_byte_order(void) {
  if (((u8 *) &(u32) { 1 })[0] == 1)
    return BYTE_LE;
  return BYTE_BE;
}

u32 host_word_order(void) {
  if (((u16 *) &(u32) { 0x100 })[0] == 0x100)
    return WORD_LE;
  return WORD_BE;
}

u32 host_dword_order(void) {
  if (((u32 *) &(u64) { 0x10000 })[0] == 0x10000)
    return DWORD_LE;
  return DWORD_BE;
}

void check_f32_format(void) {
  //  FIXME
  if ((*(u64 *) &(f64) { -1.4575323640233e-306 } & 0xffffffffull)         == 0x40301fcbull)
    return;
  if ((*(u64 *) &(f64) { -1.4575323640233e-306 } & 0xffffffff00000000ull) == 0x40301fcb00000000ull)
    return;

  FAIL("Unknown host floating-point number format",);
}

u32 host_f64_dword_order(void) {
  if ((*(u64 *) &(f64) { -1.4575323640233e-306 } & 0xffffffffull)         == 0x40301fcbull)
    return host_dword_order() == DWORD_LE ? F64_DWORD_LE : F64_DWORD_BE;
  if ((*(u64 *) &(f64) { -1.4575323640233e-306 } & 0xffffffff00000000ull) == 0x40301fcb00000000ull)
    return host_dword_order() == DWORD_LE ? F64_DWORD_BE : F64_DWORD_LE;

  FAIL("Unknown host floating-point number format", 0);
}

u32 host_data_ordering(void) {
  return host_bit_order()       |
         host_byte_order()      |
         host_word_order()      |
         host_dword_order()     |
         host_f64_dword_order();
}

u8 read_u8(u32 ordering, u8 *v, u8 *v_end) {
  CHECK(v != NULL, "Sanity", 0);
  CHECK(v < v_end, "Buffer overflow",   0);

  if ((ordering & BIT_ORDER_MASK) == host_bit_order())
    return *v;

  return
     ((*v >> 7) & 1)       |
    (((*v >> 6) & 1) << 1) |
    (((*v >> 5) & 1) << 2) |
    (((*v >> 4) & 1) << 3) |
    (((*v >> 3) & 1) << 4) |
    (((*v >> 2) & 1) << 5) |
    (((*v >> 1) & 1) << 6) |
    (((*v)      & 1) << 7);
}

u16 read_u16(u32 ordering, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity", 0);
  CHECK(v + 2 <= v_end, "Buffer overflow",   0);

  u16 x;

  if ((ordering & BIT_ORDER_MASK)  == host_bit_order() &&
      (ordering & BYTE_ORDER_MASK) == host_byte_order())
    mem_cpy(&x, v, 2);
  else if ((ordering & BYTE_ORDER_MASK) == host_byte_order())
    x =  ((u16) read_u8(ordering, v,     v_end))       |
        (((u16) read_u8(ordering, v + 1, v_end)) << 8);
  else
    x =  ((u16) read_u8(ordering, v + 1, v_end))       |
        (((u16) read_u8(ordering, v,     v_end)) << 8);

  return x;
}

u32 read_u32(u32 ordering, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity", 0);
  CHECK(v + 4 <= v_end, "Buffer overflow",   0);

  u32 x;

  if ((ordering & BIT_ORDER_MASK)  == host_bit_order()  &&
      (ordering & BYTE_ORDER_MASK) == host_byte_order() &&
      (ordering & WORD_ORDER_MASK) == host_word_order())
    mem_cpy(&x, v, 4);
  else if ((ordering & WORD_ORDER_MASK) == host_word_order())
    x =  ((u32) read_u16(ordering, v,     v_end))        |
        (((u32) read_u16(ordering, v + 2, v_end)) << 16);
  else
    x =  ((u32) read_u16(ordering, v + 2, v_end))        |
        (((u32) read_u16(ordering, v,     v_end)) << 16);

  return x;
}

u64 read_u64(u32 ordering, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity", 0);
  CHECK(v + 8 <= v_end, "Buffer overflow", 0);

  u64 x;

  if ((ordering & BIT_ORDER_MASK)   == host_bit_order()  &&
      (ordering & BYTE_ORDER_MASK)  == host_byte_order() &&
      (ordering & WORD_ORDER_MASK)  == host_word_order() &&
      (ordering & DWORD_ORDER_MASK) == host_dword_order())
    mem_cpy(&x, v, 8);
  else if ((ordering & DWORD_ORDER_MASK) == host_dword_order())
    x =  ((u64) read_u32(ordering, v,     v_end))        |
        (((u64) read_u32(ordering, v + 4, v_end)) << 32);
  else
    x =  ((u64) read_u32(ordering, v + 4, v_end))        |
        (((u64) read_u32(ordering, v,     v_end)) << 32);

  return x;
}

void write_u8(u8 ordering, u8 x, u8 *v, u8 *v_end) {
  CHECK(v != NULL, "Sanity",);
  CHECK(v < v_end, "Buffer overflow",);

  if ((ordering & BIT_ORDER_MASK) == host_bit_order())
    *v = x;
  else
    *v =
       ((x >> 7) & 1)       |
      (((x >> 6) & 1) << 1) |
      (((x >> 5) & 1) << 2) |
      (((x >> 4) & 1) << 3) |
      (((x >> 3) & 1) << 4) |
      (((x >> 2) & 1) << 5) |
      (((x >> 1) & 1) << 6) |
      (((x)      & 1) << 7);
}

void write_u16(u32 ordering, u16 x, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity",);
  CHECK(v + 2 <= v_end, "Buffer overflow",);

  if ((ordering & BIT_ORDER_MASK)  == host_bit_order() &&
      (ordering & BYTE_ORDER_MASK) == host_byte_order())
    mem_cpy(v, &x, 2);
  else if ((ordering & BYTE_ORDER_MASK) == host_byte_order()) {
    write_u8(ordering, (u8) ( x       & 0xff), v,     v_end);
    write_u8(ordering, (u8) ((x >> 8) & 0xff), v + 1, v_end);
  } else {
    write_u8(ordering, (u8) ( x       & 0xff), v + 1, v_end);
    write_u8(ordering, (u8) ((x >> 8) & 0xff), v,     v_end);
  }
}

void write_u32(u32 ordering, u32 x, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity",);
  CHECK(v + 4 <= v_end, "Buffer overflow",);

  if ((ordering & BIT_ORDER_MASK)  == host_bit_order()  &&
      (ordering & BYTE_ORDER_MASK) == host_byte_order() &&
      (ordering & WORD_ORDER_MASK) == host_word_order())
    mem_cpy(v, &x, 4);
  else if ((ordering & WORD_ORDER_MASK) == host_word_order()) {
    write_u16(ordering, (u16) ( x        & 0xffff), v,     v_end);
    write_u16(ordering, (u16) ((x >> 16) & 0xffff), v + 2, v_end);
  } else {
    write_u16(ordering, (u16) ( x        & 0xffff), v + 2, v_end);
    write_u16(ordering, (u16) ((x >> 16) & 0xffff), v,     v_end);
  }
}

void write_u64(u32 ordering, u64 x, u8 *v, u8 *v_end) {
  CHECK(v != NULL,      "Sanity",);
  CHECK(v + 8 <= v_end, "Buffer overflow",);

  if ((ordering & BIT_ORDER_MASK)   == host_bit_order()  &&
      (ordering & BYTE_ORDER_MASK)  == host_byte_order() &&
      (ordering & WORD_ORDER_MASK)  == host_word_order() &&
      (ordering & DWORD_ORDER_MASK) == host_dword_order())
    mem_cpy(v, &x, 8);
  else if ((ordering & DWORD_ORDER_MASK) == host_dword_order()) {
    write_u32(ordering, (u32) ( x        & 0xffffffffull), v,     v_end);
    write_u32(ordering, (u32) ((x >> 32) & 0xffffffffull), v + 4, v_end);
  } else {
    write_u32(ordering, (u32) ( x        & 0xffffffffull), v + 4, v_end);
    write_u32(ordering, (u32) ((x >> 16) & 0xffffffffull), v,     v_end);
  }
}

i16 read_i8(u32 ordering, void *v, void *v_end) {
  return (i8) read_u8(ordering, v, v_end);
}

i16 read_i16(u32 ordering, void *v, void *v_end) {
  return (i16) read_u16(ordering, v, v_end);
}

i32 read_i32(u32 ordering, void *v, void *v_end) {
  return (i32) read_u32(ordering, v, v_end);
}

i64 read_i64(u32 ordering, void *v, void *v_end) {
  return (i64) read_u64(ordering, v, v_end);
}

f32 read_f32(u32 ordering, void *v, void *v_end) {
  check_f32_format();
  return *(f32 *) &(u32) { read_u32(ordering, v, v_end) };
}

f64 read_f64(u32 ordering, void *v, void *v_end) {
  u64 x = read_u64(ordering, v, v_end);

  if ((ordering & F64_DWORD_ORDER_MASK) != host_f64_dword_order())
    x = ((x & 0xffffffffull) << 32) | ((x >> 32) & 0xffffffffull);

  void *p = &x;
  return *(f64 *) p;
}

void write_i8(u32 ordering, i8 x, void *v, void *v_end) {
  write_u8(ordering, (u8) x, v, v_end);
}

void write_i16(u32 ordering, i16 x, void *v, void *v_end) {
  write_u16(ordering, (u16) x, v, v_end);
}

void write_i32(u32 ordering, i32 x, void *v, void *v_end) {
  write_u32(ordering, (u32) x, v, v_end);
}

void write_i64(u32 ordering, i64 x, void *v, void *v_end) {
  write_u64(ordering, (u64) x, v, v_end);
}

void write_f32(u32 ordering, f32 x, void *v, void *v_end) {
  check_f32_format();
  void *p = &x;
  write_u32(ordering, *(u32 *) p, v, v_end);
}

void write_f64(u32 ordering, f64 x, void *v, void *v_end) {
  void *p = &x;
  if ((ordering & F64_DWORD_ORDER_MASK) == host_f64_dword_order())
    write_u64(ordering, *(u64 *) p, v, v_end);
  else {
    write_u32(ordering, *(((u32 *) p) + 1),  (u8 *) v,      v_end);
    write_u32(ordering, *  (u32 *) p,       ((u8 *) v) + 4, v_end);
  }
}

//  Shortcuts

#define HO host_data_ordering()

//  ================================================================
//
//  * Code generation and linking
//
//  ----------------------------------------------------------------
//
//  Docs and helpful materials
//
//  AR  https://man.freebsd.org/cgi/man.cgi?query=ar&sektion=5
//  ELF https://man7.org/linux/man-pages/man5/elf.5.html
//
//  https://fasterthanli.me/series/making-our-own-executable-packer
//
//  Relocation types
//  https://intezer.com/blog/malware-analysis/executable-and-linkable-format-101-part-3-relocations/
//  https://docs.oracle.com/cd/E19120-01/open.solaris/819-0690/chapter7-2/index.html
//
//  Thread-local storage
//  https://maskray.me/blog/2021-02-14-all-about-thread-local-storage
//
//  tinycc impl
//  https://repo.or.cz/tinycc.git/blob/HEAD:/x86_64-link.c
//  https://repo.or.cz/tinycc.git/blob/HEAD:/tccelf.c
//
//  Online assembler
//  https://defuse.ca/online-x86-assembler.htm
//  https://shell-storm.org/online/Online-Assembler-and-Disassembler/
//
//  Linux syscall
//  https://man7.org/linux/man-pages/man2/intro.2.html
//  https://man7.org/linux/man-pages/man2/syscalls.2.html
//  https://man7.org/linux/man-pages/man2/syscall.2.html
//
//  Linker scripts
//  https://home.cs.colorado.edu/~main/cs1300/doc/gnu/ld_3.html
//
//  ----------------------------------------------------------------
//
//  TODO Experiment with mapping several p_vaddr into one p_paddr.
//
//  ================================================================

enum {
  OS_Unknown = 0,
  OS_Unix,
  OS_Linux,
  OS_Windows,
  OS_macOS,
  OS_Cygwin,

  #if defined(__CYGWIN__)
  HOST_OS = OS_Cygwin,
  #elif defined(_WIN32)
  HOST_OS = OS_Windows,
  #elif defined(__linux__)
  HOST_OS = OS_Linux,
  #elif defined(__APPLE__)
  HOST_OS = OS_macOS,
  #elif defined(__unix__)
  HOST_OS = OS_Unix,
  #else
  HOST_OS = OS_Unknown,
  #endif

  #if defined(__x86_64) || defined(__amd_64) || defined(_M_AMD64)
  HOST_ARCH = ARCH_X86_64,
  #elif defined(__i386) || defined(_M_I86) || defined(_X86_)
  HOST_ARCH = ARCH_I386,
  #elif defined(__aarch64__)
  HOST_ARCH = ARCH_ARM64,
  #elif defined(__arm__) || defined(__thumb__) || defined(__M_ARM) || defined(__M_ARMT)
  HOST_ARCH = ARCH_ARM32,
  #else
  HOST_ARCH = ARCH_UNKNOWN,
  #endif

  //  x86_64 constants
  //

  X86_64_BASE_ADDRESS = 0x400000,
  X86_64_ALIGNMENT    = 8,

  //  NOTE For compatibility with Box64 on ARM
  X86_64_PAGE_SIZE    = 16 * 1024, // 4 * 1024

  //  ELF format constants
  //

  ELF_64          = 2,
  ELF_2_LE        = 1,
  ELF_VERSION     = 1,
  ELF_SYS_V       = 0,
  ELF_LINUX       = 3,
  ELF_ABI_VERSION = 0,
  ELF_RELOCATABLE = 1,
  ELF_EXECUTABLE  = 2,
  ELF_AARCH64     = 183,
  ELF_X86_64      = 62,

  ELF_HEADER_SIZE         = 64,
  ELF_PROGRAM_HEADER_SIZE = 56,
  ELF_SECTION_HEADER_SIZE = 64,
  ELF_SYMBOL_ENTRY_SIZE   = 24,
  ELF_REL_ENTRY_SIZE      = 16,
  ELF_RELA_ENTRY_SIZE     = 24,
  ELF_GOT_ENTRY_SIZE      = 8,
  ELF_DYNAMIC_ENTRY_SIZE  = 16,

  SEC_NONE = 0,
  SEC_PROGBITS,
  SEC_SYMTAB,
  SEC_STRTAB,
  SEC_RELA,
  SEC_HASH,
  SEC_DYNAMIC,
  SEC_NOTE,
  SEC_NOBITS,
  SEC_REL,
  SEC_SHLIB,
  SEC_DYNSYM,
  SEC_INIT_ARRAY = 14,
  SEC_FINI_ARRAY,
  SEC_PREINIT_ARRAY,
  SEC_GROUP,
  SEC_SYMTAB_SHNDX,

  SYM_NONE = 0,
  SYM_PROC,
  SYM_DATA,
  SYM_COMMON,
  SYM_TLS,
  SYM_SECTION,
  SYM_SPECIFIC,

  BIND_LOCAL = 0,
  BIND_GLOBAL,
  BIND_WEAK,

  //  Relocation types
  //

  R_X86_64_NONE = 0,
  R_X86_64_64,
  R_X86_64_PC32,
  R_X86_64_GOT32,
  R_X86_64_PLT32,
  R_X86_64_COPY,
  R_X86_64_GLOB_DAT,
  R_X86_64_JUMP_SLOT,
  R_X86_64_RELATIVE,
  R_X86_64_GOTPCREL,
  R_X86_64_32,
  R_X86_64_32S,
  R_X86_64_16,
  R_X86_64_PC16,
  R_X86_64_8,
  R_X86_64_PC8,
  R_X86_64_DTPMOD64,
  R_X86_64_DTPOFF64,
  R_X86_64_TPOFF64,
  R_X86_64_TLSGD,
  R_X86_64_TLSLD,
  R_X86_64_DTPOFF32,
  R_X86_64_GOTTPOFF,
  R_X86_64_TPOFF32,
  R_X86_64_PC64,
  R_X86_64_GOTOFF64,
  R_X86_64_GOTPC32,
  R_X86_64_GOT64,
  R_X86_64_GOTPCREL64,
  R_X86_64_GOTPC64,
  R_X86_64_GOTPLT64,
  R_X86_64_PLTOFF64,
  R_X86_64_SIZE32,
  R_X86_64_SIZE64,
  R_X86_64_GOTPC32_TLSDESC,
  R_X86_64_TLSDESC_CALL,
  R_X86_64_TLSDESC,
  R_X86_64_IRELATIVE,
  R_X86_64_RELATIVE64,
  R_X86_64_GOTPCRELX = 41,
  R_X86_64_REX_GOTPCRELX,

  //  Codegen context

  EMIT_ENTRY_PROC = 1,
};

c8 *SEC_TYPE_NAMES[] = {
  [SEC_NONE]          = "none",
  [SEC_PROGBITS]      = "progbits",
  [SEC_SYMTAB]        = "symtab",
  [SEC_STRTAB]        = "strtab",
  [SEC_RELA]          = "rela",
  [SEC_HASH]          = "hash",
  [SEC_DYNAMIC]       = "dynamic",
  [SEC_NOTE]          = "note",
  [SEC_NOBITS]        = "nobits",
  [SEC_REL]           = "rel",
  [SEC_SHLIB]         = "shlib",
  [SEC_DYNSYM]        = "dynsym",
  [12]                = "",
  [13]                = "",
  [SEC_INIT_ARRAY]    = "init array",
  [SEC_FINI_ARRAY]    = "fini array",
  [SEC_PREINIT_ARRAY] = "preinit array",
  [SEC_GROUP]         = "group",
  [SEC_SYMTAB_SHNDX]  = "symtab shndx",
};

c8 *SYM_TYPE_NAMES[] = {
  [SYM_NONE]     = "none",
  [SYM_PROC]     = "proc",
  [SYM_DATA]     = "data",
  [SYM_COMMON]   = "common",
  [SYM_TLS]      = "tls",
  [SYM_SECTION]  = "section",
  [SYM_SPECIFIC] = "spec",
};

c8 *BIND_TYPE_NAMES[] = {
  [BIND_LOCAL]  = "local",
  [BIND_GLOBAL] = "global",
  [BIND_WEAK]   = "weak",
};

c8 *REL_NAMES[] = {
  [R_X86_64_NONE]            = "none",
  [R_X86_64_64]              = "64",
  [R_X86_64_PC32]            = "pc32",
  [R_X86_64_GOT32]           = "got32",
  [R_X86_64_PLT32]           = "plt32",
  [R_X86_64_COPY]            = "copy",
  [R_X86_64_GLOB_DAT]        = "glob dat",
  [R_X86_64_JUMP_SLOT]       = "jump slot",
  [R_X86_64_RELATIVE]        = "relative",
  [R_X86_64_GOTPCREL]        = "gotpcrel",
  [R_X86_64_32]              = "32",
  [R_X86_64_32S]             = "32s",
  [R_X86_64_16]              = "16",
  [R_X86_64_PC16]            = "pc16",
  [R_X86_64_8]               = "8",
  [R_X86_64_PC8]             = "pc8",
  [R_X86_64_DTPMOD64]        = "dtpmod64",
  [R_X86_64_DTPOFF64]        = "dtpoff64",
  [R_X86_64_TPOFF64]         = "tpoff64",
  [R_X86_64_TLSGD]           = "tlsgd",
  [R_X86_64_TLSLD]           = "tlsld",
  [R_X86_64_DTPOFF32]        = "dtpoff32",
  [R_X86_64_GOTTPOFF]        = "gottpoff",
  [R_X86_64_TPOFF32]         = "tpoff32",
  [R_X86_64_PC64]            = "pc64",
  [R_X86_64_GOTOFF64]        = "gotoff64",
  [R_X86_64_GOTPC32]         = "gotpc32",
  [R_X86_64_GOT64]           = "got64",
  [R_X86_64_GOTPCREL64]      = "gotpcrel64",
  [R_X86_64_GOTPC64]         = "gotpc64",
  [R_X86_64_GOTPLT64]        = "gotplt64",
  [R_X86_64_PLTOFF64]        = "pltoff64",
  [R_X86_64_SIZE32]          = "size32",
  [R_X86_64_SIZE64]          = "size64",
  [R_X86_64_GOTPC32_TLSDESC] = "gotpc32 tlsdesc",
  [R_X86_64_TLSDESC_CALL]    = "tlsdesc call",
  [R_X86_64_TLSDESC]         = "tlsdesc",
  [R_X86_64_IRELATIVE]       = "irelative",
  [R_X86_64_RELATIVE64]      = "relative64",
  [R_X86_64_GOTPCRELX]       = "gotpcrelx",
  [R_X86_64_REX_GOTPCRELX]   = "gotpcrelx",
};

c8 ELF_MAGIC[4]      = "\x7f" "ELF";
c8 AR_MAGIC[8]       = "!<arch>\n";
c8 AR_SYMBOL_TABLE[] = "/               ";
c8 AR_STRING_TABLE[] = "//              ";

c8 SECTION_SYMTAB[] = ".symtab";
c8 SECTION_STRTAB[] = ".strtab";
c8 SECTION_GOT[]    = ".got";
c8 SECTION_PLT[]    = ".plt";
c8 SECTION_INIT[]   = ".init";
c8 SECTION_FINI[]   = ".fini";

typedef struct {
  i64 offset;
  i64 size;
} Offset_Size;

typedef struct {
  u8 *        begin;
  u8 *        end;
  Offset_Size elf;
  i64         obj_index;
} Buffer_Context;

typedef struct {
  i64 offset;
  i64 num;
} Offset_Num;

typedef struct {
  Offset_Size name;
  u32         type;
  b8          alloc;
  b8          write;
  b8          exec;
  b8          tls;
  i64         alignment;
  i64         entry_size;
  i64         num_entries;
  Offset_Size data;
} Elf_Section_Header;

typedef struct {
  Offset_Size name;
  u8          type;
  u8          bind;
  i64         section;
  Offset_Size value;
  i64         obj_index;
} Elf_Symbol_Entry;

typedef struct {
  Elf_Symbol_Entry symbol;
  i64              offset;
  u32              type;
  i64              addent;
} Elf_Relx_Entry;

//  ================================================================
//
//  Codegen
//
//  ================================================================

enum {
  EAX = 1,
  EBX,
  ECX,
  EDX,
  ESI,
  EDI,

  MOV = 1,
  ADD,
  SUB,
};

void codegen_add_rel(Pool *pool, Codegen_Context *codegen, Codegen_Rel_Entry rel) {
  CHECK(pool != NULL,    "Sanity",);
  CHECK(codegen != NULL, "Sanity",);

  i64 n = codegen->rels.size / sizeof(Codegen_Rel_Entry);
  codegen->rels = chunk_resize(pool, codegen->rels, (n + 1) * sizeof(Codegen_Rel_Entry));
  CHECK(n < codegen->rels.size / (i64) sizeof(Codegen_Rel_Entry), "Buffer overflow",);
  Codegen_Rel_Entry *rels = CHUNK(pool, codegen->rels, Codegen_Rel_Entry);
  CHECK(rels != NULL, "Internal",);
  rels[n] = rel;
}

b8 x86_64_emit_i32_mov_reg_val(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              dst,
  u32              src
) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
  u8 *end   = begin + codegen->buffer_code.size;

  switch (dst) {
    case EAX: write_u8 (LE, 0xb8, begin, end); break;
    case EBX: write_u8 (LE, 0xbb, begin, end); break;
    case ECX: write_u8 (LE, 0xb9, begin, end); break;
    case EDX: write_u8 (LE, 0xba, begin, end); break;
    case ESI: write_u8 (LE, 0xbe, begin, end); break;
    case EDI: write_u8 (LE, 0xbf, begin, end); break;
    default: FAIL("Not implemented", 0);
  }
  write_u32(LE, src, begin + 1, end);
  codegen->offset_code += 5;
  return 1;
}

b8 x86_64_emit_i32_add_reg_val(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              dst,
  u32              src
) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
  u8 *end   = begin + codegen->buffer_code.size;

  if (dst == EAX) {
    write_u8 (LE, 0x05, begin,     end);
    write_u32(LE, src,  begin + 1, end);
    codegen->offset_code += 5;
    return 1;
  }

  write_u8(LE, 0x81, begin, end);
  switch (dst) {
    case EBX: write_u8 (LE, 0xc3, begin + 1, end); break;
    case ECX: write_u8 (LE, 0xc1, begin + 1, end); break;
    case EDX: write_u8 (LE, 0xc2, begin + 1, end); break;
    case ESI: write_u8 (LE, 0xc6, begin + 1, end); break;
    case EDI: write_u8 (LE, 0xc7, begin + 1, end); break;
    default: FAIL("Not implemented", 0);
  }
  write_u32(LE, src, begin + 2, end);
  codegen->offset_code += 6;
  return 1;
}

b8 x86_64_emit_i32_sub_reg_val(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              dst,
  u32              src
) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
  u8 *end   = begin + codegen->buffer_code.size;

  if (dst == EAX) {
    write_u8 (LE, 0x2d, begin,     end);
    write_u32(LE, src,  begin + 1, end);
    codegen->offset_code += 5;
    return 1;
  }

  write_u8(LE, 0x81, begin, end);
  switch (dst) {
    case EBX:  write_u8(LE, 0xeb, begin + 1, end); break;
    case ECX:  write_u8(LE, 0xe9, begin + 1, end); break;
    case EDX:  write_u8(LE, 0xea, begin + 1, end); break;
    case ESI:  write_u8(LE, 0xee, begin + 1, end); break;
    case EDI:  write_u8(LE, 0xef, begin + 1, end); break;
    default: FAIL("Not implemented", 0);
  }
  write_u32(LE, src, begin + 2, end);
  codegen->offset_code += 6;
  return 1;
}

b8 x86_64_emit_i32_op_reg_args(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              dst,
  i64              src
) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
  u8 *end   = begin + codegen->buffer_code.size;

  switch (dst) {
    case EAX:
      switch (src) {
        case EAX: write_u8(LE, 0xc0, begin, end); break;
        case EBX: write_u8(LE, 0xd8, begin, end); break;
        case ECX: write_u8(LE, 0xc8, begin, end); break;
        case EDX: write_u8(LE, 0xd0, begin, end); break;
        case ESI: write_u8(LE, 0xf0, begin, end); break;
        case EDI: write_u8(LE, 0xf8, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    case EBX:
      switch (src) {
        case EAX: write_u8(LE, 0xc3, begin, end); break;
        case EBX: write_u8(LE, 0xd3, begin, end); break;
        case ECX: write_u8(LE, 0xcb, begin, end); break;
        case EDX: write_u8(LE, 0xd3, begin, end); break;
        case ESI: write_u8(LE, 0xf3, begin, end); break;
        case EDI: write_u8(LE, 0xfb, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    case ECX:
      switch (src) {
        case EAX: write_u8(LE, 0xc1, begin, end); break;
        case EBX: write_u8(LE, 0xd9, begin, end); break;
        case ECX: write_u8(LE, 0xc9, begin, end); break;
        case EDX: write_u8(LE, 0xd1, begin, end); break;
        case ESI: write_u8(LE, 0xf1, begin, end); break;
        case EDI: write_u8(LE, 0xf9, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    case EDX:
      switch (src) {
        case EAX: write_u8(LE, 0xc2, begin, end); break;
        case EBX: write_u8(LE, 0xda, begin, end); break;
        case ECX: write_u8(LE, 0xca, begin, end); break;
        case EDX: write_u8(LE, 0xd2, begin, end); break;
        case ESI: write_u8(LE, 0xf2, begin, end); break;
        case EDI: write_u8(LE, 0xfa, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    case ESI:
      switch (src) {
        case EAX: write_u8(LE, 0xc6, begin, end); break;
        case EBX: write_u8(LE, 0xde, begin, end); break;
        case ECX: write_u8(LE, 0xce, begin, end); break;
        case EDX: write_u8(LE, 0xd6, begin, end); break;
        case ESI: write_u8(LE, 0xf6, begin, end); break;
        case EDI: write_u8(LE, 0xfe, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    case EDI:
      switch (src) {
        case EAX: write_u8(LE, 0xc7, begin, end); break;
        case EBX: write_u8(LE, 0xdf, begin, end); break;
        case ECX: write_u8(LE, 0xcf, begin, end); break;
        case EDX: write_u8(LE, 0xd7, begin, end); break;
        case ESI: write_u8(LE, 0xf7, begin, end); break;
        case EDI: write_u8(LE, 0xff, begin, end); break;
        default:  FAIL("Not implemented", 0);
      }
      break;

    default: FAIL("Not implemented", 0);
  }
  ++codegen->offset_code;
  return 1;
}

b8 x86_64_emit_i32_op_reg_val(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              op,
  i64              dst,
  u32              src
) {
  switch (op) {
    case MOV: LOG(VERBOSE, "+ mov [%lld], %u", dst, src); return x86_64_emit_i32_mov_reg_val(pool, codegen, dst, src);
    case ADD: LOG(VERBOSE, "+ add [%lld], %u", dst, src); return x86_64_emit_i32_add_reg_val(pool, codegen, dst, src);
    case SUB: LOG(VERBOSE, "+ sub [%lld], %u", dst, src); return x86_64_emit_i32_sub_reg_val(pool, codegen, dst, src);
    default:;
  }

  FAIL("Sanity", 0);
}

b8 x86_64_emit_i32_op_reg_reg(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              op,
  i64              dst,
  i64              src
) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
  u8 *end   = begin + codegen->buffer_code.size;

  if (dst == src)
    return 1;

  switch (op) {
    case MOV: LOG(VERBOSE, "+ mov [%lld], [%lld]", dst, src); write_u8(LE, 0x89, begin, end); break;
    case ADD: LOG(VERBOSE, "+ add [%lld], [%lld]", dst, src); write_u8(LE, 0x01, begin, end); break;
    case SUB: LOG(VERBOSE, "+ sub [%lld], [%lld]", dst, src); write_u8(LE, 0x29, begin, end); break;
    default:  FAIL("Not implemented", 0);
  }
  ++codegen->offset_code;

  return x86_64_emit_i32_op_reg_args(pool, codegen, dst, src);
}

b8 x86_64_emit_node(
  Pool *           pool,
  Codegen_Context *codegen,
  Codegen_Entity  *proc,
  i64              node,
  u32              context
) {
  Node *n = node_by_id(pool, node);
  CHECK(n != NULL, "No node", 0);

  codegen->buffer_code = chunk_resize(pool, codegen->buffer_code, codegen->offset_code + 256);
  CHECK(codegen->buffer_code.size == codegen->offset_code + 256, "Buffer overflow", 0);

  i64 num_entities = pool->entities.size / (i64) sizeof(Entity);

  if (codegen->entities.size / (i64) sizeof(Codegen_Entity) != num_entities)
    codegen->entities = chunk_resize(pool, codegen->entities, num_entities * sizeof(Codegen_Entity));
  CHECK(num_entities == codegen->entities.size / (i64) sizeof(Codegen_Entity), "Buffer overflow", 0);

  Codegen_Entity *entities = CHUNK(pool, codegen->entities, Codegen_Entity);
  CHECK(entities != NULL, "Internal", 0);

  switch (n->op) {
    case OP_PTR:
    case OP_I8:
    case OP_I32:
    case OP_I64:
    case OP_ADDRESS:
      //  Do nothing
      break;

    case OP_ADD:
    case OP_SUB: {
      //  NOTE Assuming static single-assignment form.

      Node *          x_n = node_by_id(pool, n->bin_op[0]);
      Node *          y_n = node_by_id(pool, n->bin_op[1]);
      Codegen_Entity *x   = entities + n->bin_op[0];
      Codegen_Entity *y   = entities + n->bin_op[1];
      Codegen_Entity *dst = entities + node;

      CHECK(x_n != NULL, "Sanity", 0);
      CHECK(y_n != NULL, "Sanity", 0);
      CHECK(x != NULL,   "Sanity", 0);
      CHECK(y != NULL,   "Sanity", 0);

      dst->reg = 1;
      while (dst->reg <= 6 && ((1 << (dst->reg - 1)) & proc->occupied_reg) != 0)
        ++dst->reg;

      i64 op = n->op == OP_ADD ? ADD : SUB;

      switch (x_n->op) {
        case OP_I32: {
          u32 val = CHUNK(pool, x_n->lit, u32)[0];
          if (!x86_64_emit_i32_op_reg_val(pool, codegen, MOV, dst->reg, val))
            return 0;
        } break;

        case OP_ADD:
        case OP_SUB:
          if (!x86_64_emit_i32_op_reg_reg(pool, codegen, MOV, dst->reg, x->reg))
            return 0;
          proc->occupied_reg &= ~(1 << (x->reg - 1));
          x->reg              = 0;
          break;

        default:
          FAIL("Not implemented", 0);
      }

      switch (y_n->op) {
        case OP_I32: {
          u32 val = CHUNK(pool, y_n->lit, u32)[0];
          if (!x86_64_emit_i32_op_reg_val(pool, codegen, op, dst->reg, val))
            return 0;
        } break;

        case OP_ADD:
        case OP_SUB:
          if (!x86_64_emit_i32_op_reg_reg(pool, codegen, op, dst->reg, y->reg))
            return 0;
          proc->occupied_reg &= ~(1 << (y->reg - 1));
          y->reg              = 0;
        break;

        default:
          FAIL("Not implemented", 0);
      }

      proc->occupied_reg |= 1 << (dst->reg - 1);
    } break;

    case OP_CALL: {
      CHECK(n->call.convention == CONV_CDECL, "Not implemented", 0);
      CHECK(n->call.target_proc == UNDEFINED, "Not implemented", 0);
      CHECK(n->call.target_name.size > 0,     "No proc name",    0);

      u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
      u8 *end   = begin + codegen->buffer_code.size;

      i64  num_args = n->call.args.size / sizeof(i64);
      i64 *args     = CHUNK(pool, n->call.args, i64);
      CHECK(args != NULL, "Internal", 0);

      switch (num_args) {
        case 1: {
          Node *arg = node_by_id(pool, args[0]);
          CHECK(arg != NULL, "No node", 0);

          if (arg->op == OP_ADDRESS) {
            //  Write data
            //

            Node *data = node_by_id(pool, arg->ref);
            CHECK(data->op == OP_I8, "Not implemented", 0);

            i64 arg_offset = codegen->offset_ro_data;
            codegen->buffer_ro_data = chunk_resize(pool, codegen->buffer_ro_data, arg_offset + data->lit.size);
            u8 *buf = CHUNK(pool, codegen->buffer_ro_data, u8);
            CHECK(buf != NULL, "Internal", 0);
            CHECK(arg_offset + data->lit.size <= codegen->buffer_ro_data.size, "Buffer overflow", 0);

            mem_cpy(buf + arg_offset, CHUNK(pool, data->lit, u8), data->lit.size);

            //  Write code and relocations
            //

            write_u8(LE, 0x48, begin,     end); // movabs
            write_u8(LE, 0xbf, begin + 1, end); // rdi

            codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
              .type   = REL_ADD_RO_OP_ADDRESS,
              .offset = codegen->offset_code + 2,
              .size   = 8,
              .value  = arg_offset,
            });

            write_u8(LE, 0x48, begin + 10, end); // movabs
            write_u8(LE, 0xb8, begin + 11, end); // rax

            codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
              .type      = REL_ADD_PROC_ADDRESS,
              .offset    = codegen->offset_code + 12,
              .size      = 8,
              .name_size = n->call.target_name.size,
              .name      = CHUNK(pool, n->call.target_name, c8),
            });

            write_u8(LE, 0xff, begin + 20, end); // call
            write_u8(LE, 0xd0, begin + 21, end); // rax

            codegen->offset_code   += 22;
            codegen->offset_ro_data += data->lit.size;
          } else if (arg->op == OP_I32) {
            CHECK(arg->lit.size == 4, "Not implemented", 0);

            i32 val = CHUNK(pool, arg->lit, i32)[0];

            write_u8 (LE, 0xbf, begin,     end); // mov edi
            write_i32(LE, val,  begin + 1, end);
            write_u8 (LE, 0x48, begin + 5, end); // movabs
            write_u8 (LE, 0xb8, begin + 6, end); // rax

            codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
              .type      = REL_ADD_PROC_ADDRESS,
              .offset    = codegen->offset_code + 7,
              .size      = 8,
              .name_size = n->call.target_name.size,
              .name      = CHUNK(pool, n->call.target_name, c8),
            });

            write_u8(LE, 0xff, begin + 11, end); // call
            write_u8(LE, 0xd0, begin + 12, end); // rax

            codegen->offset_code += 13;
          } else {
            FAIL("Not implemented", 0);
          }
        } break;

        case 3: {
          Node *arg_0 = node_by_id(pool, args[0]);
          Node *arg_1 = node_by_id(pool, args[1]);
          Node *arg_2 = node_by_id(pool, args[2]);

          CHECK(arg_0->op == OP_PTR, "Not implemented", 0);
          CHECK(arg_1->op == OP_PTR, "Not implemented", 0);
          CHECK(arg_2->op == OP_PTR, "Not implemented", 0);

          u64 val_0 = CHUNK(pool, arg_0->lit, u64)[0];
          u64 val_1 = CHUNK(pool, arg_1->lit, u64)[0];
          u64 val_2 = CHUNK(pool, arg_2->lit, u64)[0];

          CHECK(val_0 == 0, "Not implemented", 0);
          CHECK(val_1 == 0, "Not implemented", 0);
          CHECK(val_2 == 0, "Not implemented", 0);

          write_u8(LE, 0x31, begin,     end); // xor edx
          write_u8(LE, 0xd2, begin + 1, end); // edx
          write_u8(LE, 0x31, begin + 2, end); // xor esi
          write_u8(LE, 0xf6, begin + 3, end); // esi
          write_u8(LE, 0x31, begin + 4, end); // xor edi
          write_u8(LE, 0xff, begin + 5, end); // edi
          write_u8(LE, 0x48, begin + 6, end); // movabs
          write_u8(LE, 0xb8, begin + 7, end); // rax

          codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
            .type      = REL_ADD_PROC_ADDRESS,
            .offset    = codegen->offset_code + 8,
            .size      = 8,
            .name_size = n->call.target_name.size,
            .name      = CHUNK(pool, n->call.target_name, c8),
          });

          write_u8(LE, 0xff, begin + 16, end); // call
          write_u8(LE, 0xd0, begin + 17, end); // rax

          codegen->offset_code += 18;
        } break;

        case 7: {
          Node *arg_0 = node_by_id(pool, args[0]);
          Node *arg_1 = node_by_id(pool, args[1]);
          Node *arg_2 = node_by_id(pool, args[2]);
          Node *arg_3 = node_by_id(pool, args[3]);
          Node *arg_4 = node_by_id(pool, args[4]);
          Node *arg_5 = node_by_id(pool, args[5]);
          Node *arg_6 = node_by_id(pool, args[6]);

          CHECK(arg_0->op == OP_ADDRESS, "Not implemented", 0);
          CHECK(arg_1->op == OP_I32,       "Not implemented", 0);
          CHECK(arg_2->op == OP_ADDRESS, "Not implemented", 0);
          CHECK(arg_3->op == OP_PTR,       "Not implemented", 0);
          CHECK(arg_4->op == OP_PTR,       "Not implemented", 0);
          CHECK(arg_5->op == OP_PTR,       "Not implemented", 0);
          CHECK(arg_6->op == OP_PTR,       "Not implemented", 0);

          Proc *dat_0 = proc_by_id(pool, arg_0->ref);
          CHECK(dat_0 != NULL, "No proc", 0);

          //  Write data
          //

          Node *dat_2 = node_by_id(pool, arg_2->ref);
          CHECK(dat_2 != NULL, "No node", 0);
          CHECK(dat_2->op == OP_PTR, "Not implemented", 0);

          i64 arg_2_offset = codegen->offset_ro_data;
          codegen->buffer_ro_data = chunk_resize(pool, codegen->buffer_ro_data, arg_2_offset + dat_2->lit.size);
          u8 *buf = CHUNK(pool, codegen->buffer_ro_data, u8);
          CHECK(buf != NULL, "Internal", 0);
          CHECK(arg_2_offset + dat_2->lit.size <= codegen->buffer_ro_data.size, "Buffer overflow", 0);

          mem_cpy(buf + arg_2_offset, CHUNK(pool, dat_2->lit, u8), dat_2->lit.size);

          //  Write code and relocations
          //

          write_u8 (LE, 0x48, begin,      end); // movabs
          write_u8 (LE, 0xbf, begin +  1, end); // rdi

          codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
            .type   = REL_ADD_PROC_ADDRESS,
            .offset = codegen->offset_code + 2,
            .size   = 8,
            .proc   = arg_0->ref,
          });

          u32 val_1 = CHUNK(pool, arg_1->lit, u32)[0];

          write_u8 (LE, 0xbe,  begin + 10, end); // mov esi
          write_u32(LE, val_1, begin + 11, end);
          write_u8 (LE, 0x48,  begin + 15, end); // movabs
          write_u8 (LE, 0xba,  begin + 16, end); // rdx

          codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
            .type   = REL_ADD_RO_OP_ADDRESS,
            .offset = codegen->offset_code + 17,
            .size   = 8,
            .value  = arg_2_offset,
          });

          u64 val_3 = CHUNK(pool, arg_3->lit, u64)[0];
          u64 val_4 = CHUNK(pool, arg_4->lit, u64)[0];
          u64 val_5 = CHUNK(pool, arg_5->lit, u64)[0];

          write_u8 (LE, 0x48,  begin + 25, end); // movabs
          write_u8 (LE, 0xb9,  begin + 26, end); // rcx
          write_u64(LE, val_3, begin + 27, end);
          write_u8 (LE, 0x48,  begin + 35, end); // movabs
          write_u8 (LE, 0xb8,  begin + 36, end); // r8
          write_u64(LE, val_4, begin + 37, end);
          write_u8 (LE, 0x48,  begin + 45, end); // movabs
          write_u8 (LE, 0xb9,  begin + 46, end); // r9
          write_u64(LE, val_5, begin + 47, end);

          //  rsp alignment
          write_u8(LE, 0x48, begin + 55, end); // sub rsp
          write_u8(LE, 0x83, begin + 56, end); //
          write_u8(LE, 0xec, begin + 57, end); //
          write_u8(LE, 8,    begin + 58, end); // 8

          u64 val_6 = CHUNK(pool, arg_6->lit, u64)[0];

          write_u8 (LE, 0x48,  begin + 59, end); // movabs
          write_u8 (LE, 0xb8,  begin + 60, end); // rax
          write_u64(LE, val_6, begin + 61, end);
          write_u8 (LE, 0x50,  begin + 69, end); // push rax

          write_u8 (LE, 0x48, begin + 70, end); // movabs
          write_u8 (LE, 0xb8, begin + 71, end); // rax

          codegen_add_rel(pool, codegen, (Codegen_Rel_Entry) {
            .type      = REL_ADD_PROC_ADDRESS,
            .offset    = codegen->offset_code + 72,
            .size      = 8,
            .name_size = n->call.target_name.size,
            .name      = CHUNK(pool, n->call.target_name, c8),
          });

          write_u8(LE, 0xff, begin + 80, end); // call
          write_u8(LE, 0xd0, begin + 81, end); // rax

          write_u8(LE, 0x48, begin + 82, end); // add rsp
          write_u8(LE, 0x83, begin + 83, end); //
          write_u8(LE, 0xc4, begin + 84, end); //
          write_u8(LE, 16,   begin + 85, end); // 16

          codegen->offset_code    += 86;
          codegen->offset_ro_data += dat_2->lit.size;
        } break;

        default:
          FAIL("Not implemented", 0);
      }
    } break;

    case OP_RET: {
      u8 *begin = CHUNK(pool, codegen->buffer_code, u8) + codegen->offset_code;
      u8 *end   = begin + codegen->buffer_code.size;

      i64  num_vals = n->ret.vals.size / sizeof(i64);
      i64 *vals     = CHUNK(pool, n->ret.vals, i64);
      CHECK(vals != NULL, "Internal", 0);

      if ((context & EMIT_ENTRY_PROC) != 0) {
        if (num_vals == 0) {
          write_u8 (LE, 0xb8, begin,      end); // mov eax
          write_u32(LE, 60,   begin +  1, end); // 60

          write_u8 (LE, 0xbf, begin +  5, end); // mov edi
          write_u32(LE, 0,    begin +  6, end); // 0

          write_u8 (LE, 0x0f, begin + 10, end); // syscall
          write_u8 (LE, 0x05, begin + 11, end);

          codegen->offset_code += 12;
        } else {
          if (num_vals > 1)
            LOG(WARNING, "Some return values are ignored for node %lld", node);

          Node *val = node_by_id(pool, vals[0]);
          CHECK(val != NULL, "No node", 0);

          switch (val->op) {
            case OP_I64: {
              CHECK(val->lit.size == 8, "Not implemented", 0);

              u32 a = CHUNK(pool, val->lit, u32)[0];

              write_u8 (LE, 0xb8, begin,      end); // mov eax
              write_u32(LE, 60,   begin +  1, end); // 60

              write_u8 (LE, 0xbf, begin +  5, end); // mov edi
              write_u32(LE, a,    begin +  6, end);

              write_u8 (LE, 0x0f, begin + 10, end); // syscall
              write_u8 (LE, 0x05, begin + 11, end);

              codegen->offset_code += 12;
            } break;

            case OP_ADD:
            case OP_SUB: {
              switch (entities[vals[0]].reg) {
                case EAX: break;

                case EBX:
                  write_u8 (LE, 0x89, begin,     end); // mov eax
                  write_u8 (LE, 0xd8, begin + 1, end); // ebx

                  begin                += 2;
                  codegen->offset_code += 2;
                  break;

                case ECX:
                  write_u8 (LE, 0x89, begin,     end); // mov eax
                  write_u8 (LE, 0xc8, begin + 1, end); // ecx

                  begin                += 2;
                  codegen->offset_code += 2;
                  break;

                case EDX:
                  write_u8 (LE, 0x89, begin,     end); // mov eax
                  write_u8 (LE, 0xd0, begin + 1, end); // edx

                  begin                += 2;
                  codegen->offset_code += 2;
                  break;

                default:
                  FAIL("Not implemented", 0);
              }

              write_u8 (LE, 0x89, begin,     end); // mov edi
              write_u8 (LE, 0xc7, begin + 1, end); // eax

              write_u8 (LE, 0xb8, begin + 2, end); // mov eax
              write_u32(LE, 60,   begin + 3, end); // 60

              write_u8 (LE, 0x0f, begin + 7, end); // syscall
              write_u8 (LE, 0x05, begin + 8, end);

              codegen->offset_code += 9;
            } break;

            default:
              FAIL("Not implemented", 0);
          }
        }
      } else {
        CHECK(num_vals == 1, "Not implemented", 0);

        Node *val = node_by_id(pool, vals[0]);

        switch (val->op) {
          case OP_I32: {
            CHECK(val->lit.size == 4, "Not implemented", 0);

            u32 a = CHUNK(pool, val->lit, u32)[0];

            write_u8 (LE, 0xb8, begin,     end); // mov eax
            write_u32(LE, a,    begin + 1, end);
            write_u8 (LE, 0xc3, begin + 5, end); // ret

            codegen->offset_code += 6;
          } break;

          case OP_ADD:
          case OP_SUB: {
            CHECK(entities[vals[0]].reg == EAX, "Not implemented", 0);

            write_u8(LE, 0xc3, begin, end); // ret

            codegen->offset_code += 1;
          } break;

          default:
            FAIL("Not implemented", 0);
        }
      }
    } break;

    default:
      FAIL("Unknown operation", 0);
  }

  return 1;

  #undef CHECK_NODE_
}

b8 emit_proc(
  Pool *           pool,
  Codegen_Context *codegen,
  i64              proc,
  u16              arch,
  u32              context
) {
  CHECK(arch == ARCH_X86_64, "Target not supported", 0);

  Proc *p = proc_by_id(pool, proc);
  CHECK(p != NULL, "No proc", 0);

  i64 num_entities = pool->entities.size / (i64) sizeof(Entity);
  if (codegen->entities.size / (i64) sizeof(Codegen_Entity) < num_entities)
    codegen->entities = chunk_resize(pool, codegen->entities, num_entities * sizeof(Codegen_Entity));
  CHECK(codegen->entities.size / (i64) sizeof(Codegen_Entity) >= num_entities, "Buffer overflow", 0);

  Codegen_Entity *entities = CHUNK(pool, codegen->entities, Codegen_Entity);
  CHECK(entities != NULL, "Internal", 0);
  CHECK(proc < codegen->entities.size / (i64) sizeof(Codegen_Entity), "Buffer overflow", 0);
  CHECK(entities[proc].emit_done == 0, "Emit already done", 0);

  entities[proc].offset = codegen->offset_code;

  //  TODO Sort nodes in the sequential execution order.
  //  NOTE Now we assume that nodes are already sorted.

  i64  num_nodes = p->nodes.size / sizeof(i64);
  i64 *nodes     = CHUNK(pool, p->nodes, i64);
  CHECK(nodes != NULL, "Internal", 0);

  for (i64 i = 1; i < num_nodes; ++i)
    if (entity_enabled(pool, nodes[i]))
      if (!x86_64_emit_node(pool, codegen, entities + proc, nodes[i], context))
        return 0;

  entities[proc].emit_done = 1;
  return 1;
}

b8 emit_unit(Pool *pool, Codegen_Context *codegen, i64 unit, u16 arch) {
  CHECK(pool != NULL,    "Sanity", 0);
  CHECK(codegen != NULL, "Sanity", 0);

  Unit *u = unit_by_id(pool, unit);
  CHECK(u != NULL, "No unit", 0);

  i64  num_procs = u->procs.size / sizeof(i64);
  i64 *procs     = CHUNK(pool, u->procs, i64);
  CHECK(procs != NULL, "Internal", 0);

  for (i64 i = 1; i < num_procs; ++i) {
    if (!entity_enabled(pool, procs[i]))
      continue;

    u32 context = 0;

    if (i == u->entry_point_index) {
      CHECK(!codegen->has_entry, "Multiple entry points", 0);
      codegen->entry_point = codegen->offset_code;
      codegen->has_entry   = 1;
      context |= EMIT_ENTRY_PROC;
    }

    if (!emit_proc(pool, codegen, procs[i], arch, context))
      return 0;
  }

  return 1;
}

//  ================================================================
//
//  Linking
//
//  ================================================================

void link_add_symbol(Pool *pool, Linker_Context *linker, Link_Sym_Entry sym) {
  CHECK(pool != NULL,   "Sanity",);
  CHECK(linker != NULL, "Sanity",);

  i64 n = linker->symbols.size / sizeof(Link_Sym_Entry);
  linker->symbols = chunk_resize(pool, linker->symbols, (n + 1) * sizeof(Link_Sym_Entry));
  Link_Sym_Entry *syms = CHUNK(pool, linker->symbols, Link_Sym_Entry);
  CHECK(syms != NULL, "Internal",);
  CHECK(n < linker->symbols.size / (i64) sizeof(Link_Sym_Entry), "Buffer overflow",);
  syms[n] = sym;
}

i64 ar_find_symbol_offset_by_name(
  u8 *ar_symbol_table,
  u8 *ar_end,
  c8 *name,
  c8 *name_end
) {
  CHECK(ar_symbol_table != NULL, "Sanity", -1);
  CHECK(name != NULL,            "Sanity", -1);
  CHECK(name_end > name,         "Sanity", -1);

  i64 num = (i64) read_u32((LE & ~BYTE_ORDER_MASK) | BYTE_BE, ar_symbol_table, ar_end);
  i64 len = name_end - name;

  c8 *s     = (c8 *) (ar_symbol_table + 4 * (num + 1));
  i64 index = 0;

  for (; index < num; ++index) {
    CHECK(s + len <= (c8 *) ar_end, "Buffer overflow", -1);

    if (s[len] == '\0' && mem_eq(s, name, len))
      return (i64) read_u32((LE & ~BYTE_ORDER_MASK) | BYTE_BE, ar_symbol_table + 4 * (index + 1), ar_end);

    while (*s != '\0' && s < (c8 *) ar_end)
      ++s;
    CHECK(s < (c8 *) ar_end, "Buffer overflow", -1);
    CHECK(*s == '\0',        "Buffer overflow", -1);
    ++s;
  }

  FAIL("Symbol not found", 0);
}

Buffer_Context elf_buffer_context(
  Pool *          pool,
  Linker_Context *linker,
  i64             num_obj_files,
  i64             elf_index
) {
  u8 * dependencies_buffer = CHUNK(pool, linker->dependencies_buffer, u8);
  i64 *obj_file_offsets    = CHUNK(pool, linker->obj_file_offsets, i64);

  CHECK(num_obj_files < linker->obj_file_offsets.size / (i64) sizeof(i64),  "Buffer overflow", (Buffer_Context) {0});
  CHECK(obj_file_offsets[num_obj_files] < linker->dependencies_buffer.size, "Buffer overflow", (Buffer_Context) {0});

  return (Buffer_Context) {
    .begin = dependencies_buffer,
    .end   = dependencies_buffer + obj_file_offsets[num_obj_files],
    .elf = {
      .offset = obj_file_offsets[elf_index],
      .size   = obj_file_offsets[elf_index + 1] - obj_file_offsets[elf_index],
    },
    .obj_index = elf_index,
  };
}

Offset_Num elf_section_headers(
  Buffer_Context b
) {
  u8 *begin = b.begin + b.elf.offset;
  u8 *end   = begin + b.elf.size;

  CHECK(end <= b.end, "Buffer overflow", (Offset_Num) {0});

  return (Offset_Num) {
    .offset = b.elf.offset + read_i64(LE, begin + 40, end),
    .num    = (i64) read_u16(LE, begin + 60, end),
  };
}

i64 elf_section_header_offset(
  Buffer_Context b,
  i64            index
) {
  return elf_section_headers(b).offset + ELF_SECTION_HEADER_SIZE * index;
}

Offset_Size elf_section_names_data(
  Buffer_Context b
) {
  u8 *elf_begin = b.begin + b.elf.offset;
  u8 *elf_end   = elf_begin + b.elf.size;

  CHECK(elf_end <= b.end, "Buffer overflow", (Offset_Size) {0});

  i64 string_table_index = (i64) read_u16(LE, elf_begin + 62, elf_end);

  u8 *begin = b.begin + elf_section_header_offset(b, string_table_index);

  return (Offset_Size) {
    .offset = b.elf.offset + read_i64(LE, begin + 24, elf_end),
    .size   = read_i64(LE, begin + 32, elf_end),
  };
}

Offset_Size elf_name_in_string_table(
  Buffer_Context b,
  Offset_Size    string_table,
  i64            name_offset
) {
  if (name_offset == 0)
    return (Offset_Size) {
      .offset = 0,
      .size   = 0,
    };

  c8 *begin = (c8 *) b.begin + string_table.offset + name_offset;
  c8 *end   = (c8 *) b.begin + string_table.offset + string_table.size;

  return (Offset_Size) {
    .offset = string_table.offset + name_offset,
    .size   = str_len(begin, end),
  };
}

i64 elf_find_section_index_by_name(
  Buffer_Context b,
  c8 *           name,
  i64            name_size
) {
  CHECK(name != NULL, "Sanity", 0);

  if (name_size == 0)
    return 0;

  Offset_Num  headers = elf_section_headers(b);
  Offset_Size names   = elf_section_names_data(b);

  for (i64 i = 0; i < headers.num; ++i) {
    u8 *begin      = b.begin + headers.offset + i * ELF_SECTION_HEADER_SIZE;
    i64 name_index = (i64) read_u32(LE, begin, b.end);
    Offset_Size s  = elf_name_in_string_table(b, names, name_index);

    if (str_eq(s.size, (c8 *) b.begin + s.offset, name_size, name))
      return i;
  }

  return 0;
}

Elf_Section_Header elf_section(
  Buffer_Context b,
  i64            index
) {
  Offset_Size names = elf_section_names_data(b);
  u8 *        begin = b.begin + elf_section_header_offset(b, index);
  u8 *        end   = b.begin + b.elf.offset + b.elf.size;
  CHECK(end <= b.end, "Buffer overflow", (Elf_Section_Header) {0});

  i64 name_index  = (i64) read_u32(LE, begin, end);
  i64 size        = read_i64(LE, begin + 32, end);
  i64 entry_size  = read_i64(LE, begin + 56, end);
  i64 num_entries = entry_size > 0 ? (size / entry_size) : 0;
  u32 type        = read_u32(LE, begin + 4,  end);
  u64 flags       = read_u64(LE, begin + 8,  end);

  if (type > SEC_SYMTAB_SHNDX || type == 12 || type == 13) {
    LOG(ERROR, "Section type: %d", type);
    FAIL("Unknown section type", (Elf_Section_Header) {0});
  }

  return (Elf_Section_Header) {
    .name        = elf_name_in_string_table(b, names, name_index),
    .type        = type,
    .alloc       = (flags &     2) == 2,
    .write       = (flags &     1) == 1,
    .exec        = (flags &     4) == 4,
    .tls         = (flags & 0x400) == 0x400,
    .alignment   = read_i64(LE, begin + 48, end),
    .entry_size  = entry_size,
    .num_entries = num_entries,
    .data = {
      .offset = b.elf.offset + read_i64(LE, begin + 24, end),
      .size   = size,
    },
  };
}

Elf_Section_Header elf_find_section_by_name(
  Buffer_Context b,
  c8 *           name,
  i64            name_size
) {
  i64 index = elf_find_section_index_by_name(b, name, name_size);
  return index == 0 ? (Elf_Section_Header) {0} : elf_section(b, index);
}

c8 *elf_name_from_offset(
  Buffer_Context b,
  Offset_Size    name
) {
  if (name.size == 0)
    return "";

  c8 *begin = (c8 *) (b.begin + name.offset);
  i64 len   = str_len(begin, (c8 *) b.end);

  CHECK((i64) name.size == len, "Buffer overflow", "");
  return begin;
}

i64 elf_find_related_section_index(
  Buffer_Context b,
  i64            section_index
) {
  Offset_Size    src_name = elf_section(b, section_index).name;
  Elf_Section_Header dst      = elf_section(b, section_index - 1);

  if (src_name.size > dst.name.size &&
      mem_eq(
        elf_name_from_offset(b, src_name) + (src_name.size - dst.name.size),
        elf_name_from_offset(b, dst.name),
        dst.name.size))
    return section_index - 1;

  i64 num_sections = elf_section_headers(b).num;

  for (i64 i = 0; i < num_sections; ++i) {
    if (i == section_index || i + 1 == section_index)
      continue;
    dst = elf_section(b, i);
    if (src_name.size > dst.name.size &&
        mem_eq(
          elf_name_from_offset(b, src_name) + (src_name.size - dst.name.size),
          elf_name_from_offset(b, dst.name),
          dst.name.size)) {
      LOG(WARNING, "Unexpected section order");
      return i;
    }
  }

  FAIL("Not found", 0);
}

Offset_Size elf_find_related_data(
  Buffer_Context b,
  i64            section_index
) {
  return elf_section(b, elf_find_related_section_index(b, section_index)).data;
}

Elf_Symbol_Entry elf_symbol(
  Buffer_Context b,
  Offset_Size    symbol_table,
  Offset_Size    string_table,
  i64            symbol_index
) {
  u8 *begin = b.begin + symbol_table.offset + symbol_index * ELF_SYMBOL_ENTRY_SIZE;
  u8 *end   = b.begin + symbol_table.offset + symbol_table.size;

  CHECK(end <= b.end, "Buffer overflow", (Elf_Symbol_Entry) {0});
  CHECK(end <= b.begin + b.elf.offset + b.elf.size, "Buffer overflow", (Elf_Symbol_Entry) {0});

  i64 sym_name  = (i64) read_u32(LE, begin,      end);
  u8  sym_info  = read_u8 (LE, begin +  4, end);
  i64 sym_shndx = (i64) read_u16(LE, begin +  6, end);
  i64 sym_value = read_i64(LE, begin +  8, end);
  i64 sym_size  = read_i64(LE, begin + 16, end);

  u8 type = (sym_info & 0xf) ==  0 ? SYM_NONE     :
            (sym_info & 0xf) ==  1 ? SYM_DATA     :
            (sym_info & 0xf) ==  2 ? SYM_PROC     :
            (sym_info & 0xf) ==  3 ? SYM_SECTION  :
            (sym_info & 0xf) ==  5 ? SYM_COMMON   :
            (sym_info & 0xf) ==  6 ? SYM_TLS      :
                                     SYM_SPECIFIC;

  u8 bind = (sym_info >> 4) == 1 ? BIND_GLOBAL :
            (sym_info >> 4) == 2 ? BIND_WEAK   :
                                   BIND_LOCAL;

  return (Elf_Symbol_Entry) {
    .name    = elf_name_in_string_table(b, string_table, sym_name),
    .type    = type,
    .bind    = bind,
    .section = sym_shndx,
    .value   = {
      .offset = sym_value,
      .size   = sym_size,
    },
    .obj_index = b.obj_index,
  };
}

Elf_Relx_Entry elf_relx(
  Buffer_Context b,
  Offset_Size    symbol_table,
  Offset_Size    string_table,
  Offset_Size    relocations,
  i64            relx_index,
  b8             is_rela
) {
  u8 *begin = b.begin + relocations.offset + relx_index * (is_rela ? ELF_RELA_ENTRY_SIZE : ELF_REL_ENTRY_SIZE);
  u8 *end   = begin + ELF_RELA_ENTRY_SIZE;

  CHECK(end <= b.end, "Buffer overflow", (Elf_Relx_Entry) {0});
  CHECK(end <= b.begin + b.elf.offset + b.elf.size, "Buffer overflow", (Elf_Relx_Entry) {0});
  CHECK(end <= b.begin + relocations.offset + relocations.size, "Buffer overflow", (Elf_Relx_Entry) {0});

  i64 relx_offset = read_i64(LE, begin,      end);
  u32 relx_type   = read_u32(LE, begin +  8, end);
  i64 relx_sym    = (i64) read_u32(LE, begin + 12, end);
  i64 relx_addent = is_rela ? read_i64(LE, begin + 16, end) : 0;

  return (Elf_Relx_Entry) {
    .symbol = elf_symbol(b, symbol_table, string_table, relx_sym),
    .offset = relx_offset,
    .type   = relx_type,
    .addent = relx_addent,
  };
}

Elf_Symbol_Entry elf_find_symbol_by_name(
  Buffer_Context b,
  i64            symbol_table_index,
  Offset_Size    string_table,
  c8 *           name,
  i64            name_size
) {
  Elf_Section_Header symbol_table = elf_section(b, symbol_table_index);

  for (i64 i = 0; i < symbol_table.num_entries; ++i) {
    Elf_Symbol_Entry sym = elf_symbol(b, symbol_table.data, string_table, i);

    CHECK(b.begin + sym.name.offset + name_size <= b.end, "Buffer overflow", (Elf_Symbol_Entry) {0});
    CHECK(sym.name.offset + name_size <= b.elf.size, "Buffer overflow", (Elf_Symbol_Entry) {0});

    if (str_eq(name_size, name, sym.name.size, (c8 *) b.begin + sym.name.offset))
      return sym;
  }

  FAIL("Not found", (Elf_Symbol_Entry) {0});
}

void elf_checks(Buffer_Context b) {
  u8 *begin = b.begin + b.elf.offset;
  u8 *end   = begin + b.elf.size;

  //  TODO
  CHECK(read_u16(LE, begin + 18, end) != ELF_AARCH64, "ARM64 not implemented",);

  u8 osabi = read_u8(LE, begin + 7, end);

  CHECK( read_u8 (LE, begin,      end) == ELF_MAGIC[0],    "Invalid ELF file",);
  CHECK( read_u8 (LE, begin +  1, end) == ELF_MAGIC[1],    "Invalid ELF file",);
  CHECK( read_u8 (LE, begin +  2, end) == ELF_MAGIC[2],    "Invalid ELF file",);
  CHECK( read_u8 (LE, begin +  3, end) == ELF_MAGIC[3],    "Invalid ELF file",);

  CHECK( read_u8 (LE, begin +  4, end) == ELF_64,          "Unsupported ELF file",);
  CHECK( read_u8 (LE, begin +  5, end) == ELF_2_LE,        "Unsupported ELF file",);
  CHECK( read_u8 (LE, begin +  6, end) == ELF_VERSION,     "Unsupported ELF file",);
  CHECK(   osabi == ELF_SYS_V || osabi == ELF_LINUX,       "Unsupported ELF file",);
  CHECK( read_u8 (LE, begin +  8, end) == ELF_ABI_VERSION, "Unsupported ELF file",);
  CHECK( read_u16(LE, begin + 16, end) == ELF_RELOCATABLE, "Unsupported ELF file",);
  CHECK( read_u16(LE, begin + 18, end) == ELF_X86_64,      "Unsupported ELF file",);
  CHECK( read_u32(LE, begin + 20, end) == ELF_VERSION,     "Unsupported ELF file",);

  LAX(read_u64(LE, begin + 24, end) == 0,                       "Invalid entry point");
  LAX(read_u64(LE, begin + 32, end) == 0,                       "Invalid program header offset");
  LAX(read_u32(LE, begin + 48, end) == 0,                       "Invalid flags");
  LAX(read_u16(LE, begin + 52, end) == ELF_HEADER_SIZE,         "Invalid ELF header size");
  LAX(read_u16(LE, begin + 54, end) == 0,                       "Invalid program header size");
  LAX(read_u16(LE, begin + 56, end) == 0,                       "Invalid num program headers");
  LAX(read_u16(LE, begin + 58, end) == ELF_SECTION_HEADER_SIZE, "Invalid section header size");
}

i64 unit_write_in_memory(
  Pool *           pool,
  Codegen_Context *codegen,
  Linker_Context * linker,
  i64              unit,
  u16              format,
  u16              arch
) {
  CHECK(format == FORMAT_ELF && arch == ARCH_X86_64, "Target not supported", 0);

  if (!emit_unit(pool, codegen, unit, arch))
    return 0;

  u16 num_program_headers = 10;
  i64 program_offset      = align(ELF_HEADER_SIZE + ELF_PROGRAM_HEADER_SIZE * num_program_headers, X86_64_PAGE_SIZE);

  i64 base_address    = X86_64_BASE_ADDRESS;
  i64 rx_code_address = base_address + program_offset;

  i64 rx_code_size     = codegen->offset_code;
  i64 ro_data_size     = codegen->offset_ro_data;
  i64 rw_data_size     = 0;
  i64 rw_zval_size     = 0;
  i64 rw_got_size      = ELF_GOT_ENTRY_SIZE;
  i64 rw_dynamic_size  = ELF_DYNAMIC_ENTRY_SIZE;
  i64 rw_tls_data_size = 0;
  i64 rw_tls_zval_size = 0;

  i64 num_sections_total = 0;
  i64 num_symbols        = 0;

  //  ==========================================================
  //
  //  Calculate section offsets

  for (i64 elf_index = 0; elf_index < linker->num_obj_files; ++elf_index) {
    Buffer_Context buf = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);

    elf_checks(buf);

    Offset_Num headers = elf_section_headers(buf);

    for (i64 sec_index = 1; sec_index < headers.num; ++sec_index, ++num_sections_total) {
      Elf_Section_Header section = elf_section(buf, sec_index);
      c8 *               name    = elf_name_from_offset(buf, section.name);

      if (section.type == SEC_PROGBITS                 &&
          STR_EQ(section.name.size, name, SECTION_GOT)) {
        FAIL("Not implemented", 0);
      }

      if (section.type == SEC_PROGBITS                 &&
          STR_EQ(section.name.size, name, SECTION_PLT)) {
        FAIL("Not implemented", 0);
      }

      if (!section.alloc || section.data.size == 0)
        continue;

      linker->sections = chunk_resize(pool, linker->sections, (num_sections_total + 1) * sizeof(Link_Sec_Entry));
      Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);
      CHECK(sections != NULL, "Internal", 0);
      CHECK(num_sections_total < linker->sections.size / (i64) sizeof(Link_Sec_Entry), "Buffer overflow", 0);

      if (section.tls) {
        if (section.type == SEC_PROGBITS) {
          sections[num_sections_total].offset  = rw_tls_data_size;
          sections[num_sections_total].address = rw_tls_data_size;
          rw_tls_data_size += align(section.data.size, X86_64_ALIGNMENT);
          continue;
        }

        if (section.type == SEC_NOBITS) {
          sections[num_sections_total].address = rw_tls_zval_size;
          rw_tls_zval_size += align(section.data.size, X86_64_ALIGNMENT);
          continue;
        }

        FAIL("Not implemented", 0);
      }

      if (section.type == SEC_DYNAMIC) {
        FAIL("Not implemented", 0);
      }

      if (section.exec) {
        CHECK(!section.write, "Not implemented", 0);

        sections[num_sections_total].offset  = rx_code_size;
        sections[num_sections_total].address = rx_code_size;
        rx_code_size += align(section.data.size, X86_64_ALIGNMENT);
        continue;
      }

      if (section.write && section.type == SEC_NOBITS) {
        sections[num_sections_total].address = rw_zval_size;
        rw_zval_size += align(section.data.size, X86_64_ALIGNMENT);
        continue;
      }

      if (section.write) {
        sections[num_sections_total].offset  = rw_data_size;
        sections[num_sections_total].address = rw_data_size;
        rw_data_size += align(section.data.size, X86_64_ALIGNMENT);
        continue;
      }

      sections[num_sections_total].offset  = ro_data_size;
      sections[num_sections_total].address = ro_data_size;
      ro_data_size += align(section.data.size, X86_64_ALIGNMENT);
    }
  }

  //  ==========================================================
  //
  //  Calculate global offset table size
  {
    i64 prev_num_symbols = num_symbols;

    for (i64 elf_index = 0; elf_index < linker->num_obj_files; ++elf_index) {
      Buffer_Context buf          = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);
      i64            num_sections = elf_section_headers(buf).num;

      Offset_Size strtab = elf_find_section_by_name(buf, SECTION_STRTAB, sizeof SECTION_STRTAB - 1).data;
      Offset_Size symtab = elf_find_section_by_name(buf, SECTION_SYMTAB, sizeof SECTION_SYMTAB - 1).data;

      for (i64 sec_index = 1; sec_index < num_sections; ++sec_index) {
        Elf_Section_Header src_sec = elf_section(buf, sec_index);
        if (src_sec.type != SEC_REL && src_sec.type != SEC_RELA)
          continue;

        for (i64 entry_index = 0; entry_index < src_sec.num_entries; ++entry_index) {
          Elf_Relx_Entry relx     = elf_relx(buf, symtab, strtab, src_sec.data, entry_index, src_sec.type == SEC_RELA);
          c8 *           sym_name = elf_name_from_offset(buf, relx.symbol.name);

          CHECK(relx.symbol.section != 65521, "Sanity", 0);
          CHECK(relx.symbol.section != 65522, "Sanity", 0);

          switch (relx.type) {
            case R_X86_64_GOT32:
            case R_X86_64_GOTPCREL:
            case R_X86_64_GOTPCRELX:
            case R_X86_64_REX_GOTPCRELX:
              if (!STR_EQ(relx.symbol.name.size, sym_name, "_DYNAMIC")) {
                b8 found = 0;

                Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols, Link_Sym_Entry);
                CHECK(symbols != NULL, "Internal", 0);
                CHECK(num_symbols <= linker->symbols.size / (i64) sizeof(Link_Sym_Entry), "Buffer overflow", 0);

                for (i64 i = 0; i < num_symbols; ++i)
                  if (relx.symbol.name.size > 0) {
                    if (str_eq(symbols[i].name_size, symbols[i].name, relx.symbol.name.size, sym_name)) {
                      found = 1;
                      break;
                    }
                  } else {
                    if (symbols[i].obj_index == relx.symbol.obj_index    &&
                        symbols[i].sec_index == relx.symbol.section      &&
                        symbols[i].address   == relx.symbol.value.offset) {
                      found = 1;
                      break;
                    }
                  }

                if (found)
                  break;

                link_add_symbol(pool, linker, (Link_Sym_Entry) {
                  .name_size = relx.symbol.name.size,
                  .name      = sym_name,
                  .address   = relx.symbol.value.offset,
                  .obj_index = relx.symbol.obj_index,
                  .sec_index = relx.symbol.section,
                });

                rw_got_size += ELF_GOT_ENTRY_SIZE;
              }
              break;

            default:;
          }
        }
      }
    }

    num_symbols = prev_num_symbols;
  }

  //  ==========================================================
  //
  //  Adjust section offsets

  i64 ro_data_address     = align(rx_code_address     + rx_code_size,     X86_64_PAGE_SIZE);
  i64 rw_data_address     = align(ro_data_address     + ro_data_size,     X86_64_PAGE_SIZE);
  i64 rw_zval_address     = align(rw_data_address     + rw_data_size,     X86_64_PAGE_SIZE);
  i64 rw_got_address      = align(rw_zval_address     + rw_zval_size,     X86_64_PAGE_SIZE);
  i64 rw_dynamic_address  = align(rw_got_address      + rw_got_size,      X86_64_PAGE_SIZE);
  i64 rw_tls_data_address = align(rw_dynamic_address  + rw_dynamic_size,  X86_64_PAGE_SIZE);
  i64 rw_tls_zval_address = align(rw_tls_data_address + rw_tls_data_size, X86_64_PAGE_SIZE);

  i64 rx_code_offset     = program_offset;
  i64 ro_data_offset     = align(rx_code_offset    + rx_code_size,    X86_64_PAGE_SIZE);
  i64 rw_data_offset     = align(ro_data_offset    + ro_data_size,    X86_64_PAGE_SIZE);
  i64 rw_got_offset      = align(rw_data_offset    + rw_data_size,    X86_64_PAGE_SIZE);
  i64 rw_dynamic_offset  = align(rw_got_offset     + rw_got_size,     X86_64_PAGE_SIZE);
  i64 rw_tls_data_offset = align(rw_dynamic_offset + rw_dynamic_size, X86_64_PAGE_SIZE);

  //  ----------------------------------------------------------

  for (i64 elf_index = 0, sec_index_global = 0; elf_index < linker->num_obj_files; ++elf_index) {
    Buffer_Context buf     = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);
    Offset_Num     headers = elf_section_headers(buf);

    for (i64 sec_index = 1; sec_index < headers.num; ++sec_index, ++sec_index_global) {
      CHECK(sec_index_global < num_sections_total, "Buffer overflow", 0);

      Elf_Section_Header section = elf_section(buf, sec_index);
      c8 *               name    = elf_name_from_offset(buf, section.name);

      if (section.type == SEC_PROGBITS                 &&
          STR_EQ(section.name.size, name, SECTION_GOT)) {
        FAIL("Not implemented", 0);
      }

      if (section.type == SEC_PROGBITS                 &&
          STR_EQ(section.name.size, name, SECTION_PLT)) {
        FAIL("Not implemented", 0);
      }

      if (!section.alloc || section.data.size == 0)
        continue;

      Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);
      CHECK(sections != NULL, "Internal", 0);
      CHECK(sec_index_global < linker->sections.size / (i64) sizeof(Link_Sec_Entry), "Buffer overflow", 0);

      if (section.tls) {
        if (section.type == SEC_PROGBITS) {
          sections[sec_index_global].offset  += rw_tls_data_offset;
          sections[sec_index_global].address += rw_tls_data_address;
          continue;
        }

        if (section.type == SEC_NOBITS) {
          sections[sec_index_global].address += rw_tls_zval_address;
          continue;
        }

        FAIL("Not implemented", 0);
      }

      if (section.type == SEC_DYNAMIC) {
        FAIL("Not implemented", 0);
      }

      if (section.exec) {
        CHECK(!section.write, "Not implemented", 0);

        sections[sec_index_global].offset  += rx_code_offset  + codegen->offset_code;
        sections[sec_index_global].address += rx_code_address + codegen->offset_code;
        continue;
      }

      if (section.write && section.type == SEC_NOBITS) {
        sections[sec_index_global].address += rw_zval_address;
        continue;
      }

      if (section.write) {
        sections[sec_index_global].offset  += rw_data_offset;
        sections[sec_index_global].address += rw_data_address;
        continue;
      }

      sections[sec_index_global].offset  += ro_data_offset  + codegen->offset_ro_data;
      sections[sec_index_global].address += ro_data_address + codegen->offset_ro_data;
    }
  }

  //  ==========================================================
  //
  //  Relocate defined symbols

  for (i64 elf_index = 0, sec_index_global = 0; elf_index < linker->num_obj_files; ++elf_index) {
    Buffer_Context buf = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);

    Offset_Num  headers = elf_section_headers(buf);
    Offset_Size strtab  = elf_find_section_by_name(buf, SECTION_STRTAB, sizeof SECTION_STRTAB - 1).data;

    for (i64 sec_index = 1; sec_index < headers.num; ++sec_index) {
      Elf_Section_Header tab = elf_section(buf, sec_index);
      if (tab.type != SEC_SYMTAB)
        continue;

      for (i64 sym_index = 1; sym_index < tab.num_entries; ++sym_index) {
        Elf_Symbol_Entry sym      = elf_symbol(buf, tab.data, strtab, sym_index);
        c8 *             sym_name = elf_name_from_offset(buf, sym.name);

        if (sym.type == SYM_TLS && sym.section != 0)
          CHECK(elf_section(buf, sym.section).tls, "Sanity", 0);

        if (sym.section == 0) // undefined symbol
          continue;
        if (sym.section == 65522) { // common
          LOG(INFO, "Common symbol: %s", sym_name);
          continue;
        }

        i64 sym_address = sym.value.offset;

        Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);
        CHECK(sections != NULL, "Internal", 0);

        if (sym.section != 65521 && elf_section(buf, sym.section).alloc) {
          i64 sym_section = sec_index_global + sym.section - 1;
          CHECK(sym_section < linker->sections.size / (i64) sizeof(Link_Sec_Entry), "Buffer overflow", 0);
          CHECK(sym_section < num_sections_total, "Buffer overflow", 0);
          CHECK(sections[sym_section].address != 0, "Sanity", 0);
          sym_address += sections[sym_section].address;
        }

        link_add_symbol(pool, linker, (Link_Sym_Entry) {
          .name_size = sym.name.size,
          .name      = sym_name,
          .address   = sym_address,
          .size      = sym.value.size,
        });

        u8 *begin = buf.begin + tab.data.offset + sym_index * ELF_SYMBOL_ENTRY_SIZE;
        u8 *end   = begin + tab.data.size;

        if (end > buf.end)
          end = buf.end;
      }
    }

    sec_index_global += elf_section_headers(buf).num - 1;
  }

  //  ==========================================================
  //
  //  TODO Add internal symbols

  //  ==========================================================
  //
  //  Add runtime library symbols

  #define ADD_UNIQUE_(i_, name_, ...)                  \
    do {                                               \
      b8 found_ = 0;                                   \
      Link_Sym_Entry *symbols_ =                       \
        CHUNK(pool, linker->symbols, Link_Sym_Entry);  \
      CHECK(symbols_ != NULL, "Internal", 0);          \
      CHECK(num_symbols <=                             \
            linker->symbols.size /                     \
            (i64) sizeof(Link_Sym_Entry),              \
            "Buffer overflow", 0);                     \
      for (i_ = 0; i_ < num_symbols; ++i_)             \
        if (STR_EQ(symbols_[i_].name_size,             \
                   symbols_[i_].name,                  \
                   name_)) {                           \
          found_ = 1;                                  \
          break;                                       \
        }                                              \
      CHECK(!found_, "Forbidden symbol: " name_, 0);   \
      link_add_symbol(pool, linker, (Link_Sym_Entry) { \
        .name_size = sizeof name_ - 1,                 \
        .name      = name_,                            \
        __VA_ARGS__                                    \
      });                                              \
    } while (0)

  #define ADD_IF_MISSING_(name_, ...)                    \
    do {                                                 \
      b8 found_ = 0;                                     \
      Link_Sym_Entry *symbols_ =                         \
        CHUNK(pool, linker->symbols, Link_Sym_Entry);    \
      CHECK(symbols_ != NULL, "Internal", 0);            \
      CHECK(num_symbols <=                               \
            linker->symbols.size /                       \
            (i64) sizeof(Link_Sym_Entry),                \
            "Buffer overflow", 0);                       \
      for (i_ = 0; i_ < num_symbols; ++i_)               \
        if (STR_EQ(symbols_[i_].name_size,               \
                   symbols_[i_].name,                    \
                   name_)) {                             \
          found_ = 1;                                    \
          break;                                         \
        }                                                \
      if (!found_) {                                     \
        link_add_symbol(pool, linker, (Link_Sym_Entry) { \
          .name_size = sizeof name_ - 1,                 \
          .name      = name_,                            \
          __VA_ARGS__                                    \
        });                                              \
      }                                                  \
    } while (0)

  //  ----------------------------------------------------------

  i64 sym_index_got;
  i64 sym_index_dynamic;

  ADD_UNIQUE_(sym_index_got,     "_GLOBAL_OFFSET_TABLE_", .address = rw_got_address, .size = rw_got_size);
  ADD_UNIQUE_(sym_index_dynamic, "_DYNAMIC", .address = rw_dynamic_address, .size = rw_dynamic_size, .got_offset = 0);

  {
    i64 i_;

    ADD_IF_MISSING_("__ehdr_start", .address = base_address, .size = ELF_HEADER_SIZE);

    ADD_IF_MISSING_("__pthread_initialize_minimal",);

    ADD_IF_MISSING_("__preinit_array_start",);
    ADD_IF_MISSING_("__preinit_array_end",);
    ADD_IF_MISSING_("__init_array_start",);
    ADD_IF_MISSING_("__init_array_end",);
    ADD_IF_MISSING_("__fini_array_start",);
    ADD_IF_MISSING_("__fini_array_end",);
    ADD_IF_MISSING_("__rela_iplt_start",);
    ADD_IF_MISSING_("__rela_iplt_end",);
    ADD_IF_MISSING_("__start___libc_atexit",);
    ADD_IF_MISSING_("__stop___libc_atexit",);
    ADD_IF_MISSING_("__start___libc_IO_vtables",);
    ADD_IF_MISSING_("__stop___libc_IO_vtables",);
    ADD_IF_MISSING_("__start___libc_subfreeres",);
    ADD_IF_MISSING_("__stop___libc_subfreeres",);
    ADD_IF_MISSING_("__start___libc_freeres_ptrs",);
    ADD_IF_MISSING_("__stop___libc_freeres_ptrs",);

    ADD_IF_MISSING_("_init",);
    ADD_IF_MISSING_("_fini",);
    ADD_IF_MISSING_("_end",);
    ADD_IF_MISSING_("_dl_rtld_map",);
    ADD_IF_MISSING_("__gmon_start__",);

    ADD_IF_MISSING_("__gcc_personality_v0",);
    ADD_IF_MISSING_("_Unwind_Resume",);
    ADD_IF_MISSING_("_Unwind_ForcedUnwind",);
    ADD_IF_MISSING_("_Unwind_Backtrace",);
    ADD_IF_MISSING_("_Unwind_GetCFA",);
    ADD_IF_MISSING_("_Unwind_GetIP",);

    ADD_IF_MISSING_("__addtf3",);
    ADD_IF_MISSING_("__subtf3",);
    ADD_IF_MISSING_("__multf3",);
    ADD_IF_MISSING_("__divtf3",);
    ADD_IF_MISSING_("__eqtf2",);
    ADD_IF_MISSING_("__letf2",);
    ADD_IF_MISSING_("__lttf2",);
    ADD_IF_MISSING_("__getf2",);
    ADD_IF_MISSING_("__gttf2",);
    ADD_IF_MISSING_("__unordtf2",);
  }

  #undef ADD_UNIQUE_
  #undef ADD_IF_MISSING_

  //  ==========================================================
  //
  //  TODO Resolve internal symbols

  //  ==========================================================
  //
  //  Process relocations and build global offset table

  for (i64 elf_index        = 0, sec_index_global = 0,
           rel_index_global = 0, got_offset       = 0;
       elf_index < linker->num_obj_files;
       ++elf_index) {
    Buffer_Context buf          = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);
    i64            num_sections = elf_section_headers(buf).num;

    Offset_Size strtab = elf_find_section_by_name(buf, SECTION_STRTAB, sizeof SECTION_STRTAB - 1).data;
    Offset_Size symtab = elf_find_section_by_name(buf, SECTION_SYMTAB, sizeof SECTION_SYMTAB - 1).data;

    for (i64 sec_index = 1; sec_index < num_sections; ++sec_index) {
      Elf_Section_Header src_sec = elf_section(buf, sec_index);
      if (src_sec.type != SEC_REL && src_sec.type != SEC_RELA)
        continue;

      // i64 dst_index        = elf_find_related_section_index(buf, sec_index);
      // i64 dst_index_global = sec_index_global + dst_index - 1;

      for (i64 entry_index = 0; entry_index < src_sec.num_entries; ++entry_index, ++rel_index_global) {
        Elf_Relx_Entry relx             = elf_relx(buf, symtab, strtab, src_sec.data, entry_index, src_sec.type == SEC_RELA);
        c8 *           sym_name         = elf_name_from_offset(buf, relx.symbol.name);
        i64            sym_index_global = num_symbols;

        CHECK(relx.symbol.section != 65521, "Sanity", 0);
        CHECK(relx.symbol.section != 65522, "Sanity", 0);

        if (relx.symbol.section == 0) {
          b8 found = 0;

          i64     num_entities = pool->entities.size / sizeof(Entity);
          Entity *entities     = CHUNK(pool, pool->entities, Entity);
          CHECK(entities != NULL, "Internal", 0);

          Codegen_Entity *codegen_entities = CHUNK(pool, codegen->entities, Codegen_Entity);
          CHECK(codegen_entities != NULL, "Internal", 0);
          CHECK(codegen->entities.size / (i64) sizeof(Codegen_Entity) >= num_entities, "Buffer overflow", 0);

          for (i64 i = 0; i < num_entities; ++i)
            if (entities[i].is_enabled             &&
                entities[i].type == ENTITY_PROC    &&
                str_eq(entities[i].proc.name.size,
                       CHUNK(pool, entities[i].proc.name, c8),
                       relx.symbol.name.size, sym_name)) {
              CHECK(codegen_entities[i].emit_done, "No proc code", 0);

              link_add_symbol(pool, linker, (Link_Sym_Entry) {
                .address = rx_code_address + codegen_entities[i].offset,
                .size    = relx.symbol.value.size,
              });

              found = 1;
              break;
            }

          Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols, Link_Sym_Entry);
          CHECK(symbols != NULL, "Internal", 0);
          CHECK(num_symbols <= linker->symbols.size / (i64) sizeof(Link_Sym_Entry), "Buffer overflow", 0);

          if (!found)
            for (i64 i = 0; i < num_symbols; ++i)
              if (str_eq(symbols[i].name_size, symbols[i].name, relx.symbol.name.size, sym_name)) {
                sym_index_global = i;
                found = 1;
                break;
              }

          if (!found) {
            LOG(ERROR, "Undefined symbol: %s", sym_name);
            FAIL("Link failed", 0);
          }
        } else {
          i64 const SEARCH_RANGE = 1024;

          Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);
          CHECK(sections != NULL, "Internal", 0);
          CHECK(sec_index_global < linker->sections.size / (i64) sizeof(Link_Sec_Entry), "Buffer overflow", 0);

          Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols, Link_Sym_Entry);
          CHECK(symbols != NULL, "Internal", 0);
          CHECK(num_symbols <= linker->symbols.size / (i64) sizeof(Link_Sym_Entry), "Buffer overflow", 0);

          i64 src_index_global = sec_index_global + relx.symbol.section - 1;
          i64 address          = relx.symbol.value.offset + sections[src_index_global].address;

          b8 found = 0;

          for (i64 k = 1; k <= num_symbols && k <= SEARCH_RANGE; ++k)
            if (symbols[num_symbols - k].address == address) {
              sym_index_global = num_symbols - k;
              found = 1;
              break;
            }

          if (!found)
            link_add_symbol(pool, linker, (Link_Sym_Entry) {
              .address = address,
              .size    = relx.symbol.value.size,
            });
        }

        if (sym_index_global >= num_symbols)
          LOG(ERROR, "Symbol: %s", sym_name);
        CHECK(sym_index_global < num_symbols, "Symbol not found", 0);

        i64 num_rels = linker->rels.size / sizeof(Link_Rel_Entry);
        if (rel_index_global >= num_rels) {
          num_rels = rel_index_global + 1;
          linker->rels = chunk_resize(pool, linker->rels, num_rels * sizeof(Link_Rel_Entry));
        }
        Link_Rel_Entry *rels = CHUNK(pool, linker->rels, Link_Rel_Entry);
        CHECK(rels != NULL, "Internal", 0);
        CHECK(rel_index_global < linker->rels.size / (i64) sizeof(Link_Rel_Entry), "Buffer overflow", 0);

        rels[rel_index_global].symbol = sym_index_global;

        switch (relx.type) {
          case R_X86_64_GOT32:
          case R_X86_64_GOTPCREL:
          case R_X86_64_GOTPCRELX:
          case R_X86_64_REX_GOTPCRELX: {
            Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols, Link_Sym_Entry);
            CHECK(symbols != NULL, "Internal", 0);

            if (!STR_EQ(relx.symbol.name.size, sym_name, "_DYNAMIC") &&
                symbols[sym_index_global].got_offset == 0) {
              got_offset += ELF_GOT_ENTRY_SIZE;
              CHECK(got_offset < rw_got_size, "Sanity", 0);
              symbols[sym_index_global].got_offset = got_offset;
            }
          } break;

          default:;
        }
      }
    }

    sec_index_global += num_sections - 1;
  }

  //  ==============================================================
  //
  //  Apply relocations

  for (i64 elf_index = 0, sec_index_global = 0, rel_index_global = 0; elf_index < linker->num_obj_files; ++elf_index) {
    Buffer_Context buf          = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);
    i64            num_sections = elf_section_headers(buf).num;

    Offset_Size strtab = elf_find_section_by_name(buf, SECTION_STRTAB, sizeof SECTION_STRTAB - 1).data;
    Offset_Size symtab = elf_find_section_by_name(buf, SECTION_SYMTAB, sizeof SECTION_SYMTAB - 1).data;

    for (i64 sec_index = 1; sec_index < num_sections; ++sec_index) {
      Elf_Section_Header src_sec = elf_section(buf, sec_index);
      if (src_sec.type != SEC_REL && src_sec.type != SEC_RELA)
        continue;

      i64 dst_index        = elf_find_related_section_index(buf, sec_index);
      i64 dst_index_global = sec_index_global + dst_index - 1;

      for (i64 entry_index = 0; entry_index < src_sec.num_entries; ++entry_index, ++rel_index_global) {
        Link_Rel_Entry *rels     = CHUNK(pool, linker->rels,     Link_Rel_Entry);
        Link_Sym_Entry *symbols  = CHUNK(pool, linker->symbols,  Link_Sym_Entry);
        Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);

        CHECK(rels != NULL,     "Internal", 0);
        CHECK(symbols != NULL,  "Internal", 0);
        CHECK(sections != NULL, "Internal", 0);

        Elf_Relx_Entry relx     = elf_relx(buf, symtab, strtab, src_sec.data, entry_index, src_sec.type == SEC_RELA);
        c8 *           sym_name = elf_name_from_offset(buf, relx.symbol.name);
        Link_Sym_Entry symbol   = symbols[rels[rel_index_global].symbol];

        u8 *dst = buf.begin + elf_section(buf, dst_index).data.offset + relx.offset;

        //  TODO Implement GOT and PLT.

        // Represents the addend used to compute the value of the relocatable field.
        i64 A = relx.addent;

        // Represents the base address at which a shared object has been loaded into memory during execution. Generally, a shared object is built with a 0 base virtual address, but the execution address will be different.
        i64 B = sections[dst_index_global].address;

        // Represents the place (section offset or address) of the storage unit being relocated (computed using r_offset).
        i64 P = sections[dst_index_global].address + relx.offset;

        // Represents the value of the symbol whose index resides in the relocation entry.
        i64 S = symbol.address;

        // The size of the symbol whose index resides in the relocation entry.
        i64 Z = symbol.size;

        // Represents the address of the global offset table.
        i64 GOT = rw_got_address;

        // Represents the offset into the global offset table at which the relocation entry's symbol will reside during execution.
        i64 G = symbol.got_offset;

        // Represents the place (section offset or address) of the Procedure Linkage Table entry for a symbol.
        i64 L = S; // TODO

        switch (relx.type) {
          #define SKIP_(x)                                                   \
            if (str_eq(relx.symbol.name.size, sym_name, sizeof(#x) - 1, #x)) \
              break;

          case R_X86_64_64:
          case R_X86_64_PC32:
          case R_X86_64_PLT32:
          case R_X86_64_GOTTPOFF:
          case R_X86_64_TPOFF32:

            SKIP_(__preinit_array_start);
            SKIP_(__preinit_array_end);
            SKIP_(__init_array_start);
            SKIP_(__init_array_end);
            SKIP_(__fini_array_start);
            SKIP_(__fini_array_end);
            SKIP_(__gcc_personality_v0);
            SKIP_(__pthread_initialize_minimal);

            SKIP_(_init);
            SKIP_(_fini);

            SKIP_(_end);
            SKIP_(_Unwind_Resume);
            SKIP_(_Unwind_Backtrace);
            SKIP_(_Unwind_ForcedUnwind);
            SKIP_(_Unwind_GetIP);
            SKIP_(_Unwind_GetCFA);

            SKIP_(__addtf3);
            SKIP_(__subtf3);
            SKIP_(__multf3);
            SKIP_(__divtf3);
            SKIP_(__eqtf2);
            SKIP_(__lttf2);
            SKIP_(__letf2);
            SKIP_(__gttf2);
            SKIP_(__getf2);
            SKIP_(__unordtf2);

            if (S == 0)
              LOG(ERROR, "Check symbol: %s", sym_name);
            CHECK(S != 0, "Symbol address is 0", 0);
            break;

          #undef SKIP_

          default:;
        }

        switch (relx.type) {
          #define ADD_(BITS, OP)                              \
            do {                                              \
              i64 x_ = read_i##BITS(LE, dst, buf.end) + (OP); \
              write_i##BITS(LE, (i##BITS) x_, dst, buf.end);  \
            } while (0)

          #define TODO_ FAIL("Not implemented", 0)

          case R_X86_64_NONE:            /* Do nothing */           break;
          case R_X86_64_64:              ADD_(64, S + A);           break;
          case R_X86_64_PC32:            ADD_(32, S + A - P);       break;
          case R_X86_64_GOT32:           TODO_;                     break;
          case R_X86_64_PLT32:           ADD_(32, L + A - P);       break;
          case R_X86_64_COPY:            /* Do nothing */           break;
          case R_X86_64_GLOB_DAT:        ADD_(64, S);               break;
          case R_X86_64_JUMP_SLOT:       ADD_(64, S);               break;
          case R_X86_64_RELATIVE:        ADD_(64, B + A);           break;
          case R_X86_64_GOTPCREL:        ADD_(32, GOT + G + A - P); break;
          case R_X86_64_32:              ADD_(32, S + A);           break;
          case R_X86_64_32S:             ADD_(32, S + A);           break;
          case R_X86_64_16:              ADD_(16, S + A);           break;
          case R_X86_64_PC16:            ADD_(16, S + A - P);       break;
          case R_X86_64_8:               ADD_(8,  S + A);           break;
          case R_X86_64_PC8:             ADD_(8,  S + A - P);       break;
          case R_X86_64_DTPMOD64:        TODO_;                     break;
          case R_X86_64_DTPOFF64:        TODO_;                     break;
          case R_X86_64_TPOFF64:         TODO_;                     break;
          case R_X86_64_TLSGD:           TODO_;                     break;
          case R_X86_64_TLSLD:           TODO_;                     break;
          case R_X86_64_DTPOFF32:        TODO_;                     break;
          case R_X86_64_GOTTPOFF:        ADD_(32, S - GOT);         break;
          case R_X86_64_TPOFF32:         ADD_(32, S + A - B);       break;
          case R_X86_64_PC64:            ADD_(64, S + A - P);       break;
          case R_X86_64_GOTOFF64:        TODO_;                     break;
          case R_X86_64_GOTPC32:         ADD_(32, GOT + A - P);     break;
          case R_X86_64_GOT64:           TODO_;                     break;
          case R_X86_64_GOTPCREL64:      TODO_;                     break;
          case R_X86_64_GOTPC64:         ADD_(64, GOT + A - P);     break;
          case R_X86_64_GOTPLT64:        TODO_;                     break;
          case R_X86_64_PLTOFF64:        TODO_;                     break;
          case R_X86_64_SIZE32:          ADD_(32, Z + A);           break;
          case R_X86_64_SIZE64:          ADD_(64, Z + A);           break;
          case R_X86_64_GOTPC32_TLSDESC: TODO_;                     break;
          case R_X86_64_TLSDESC_CALL:    TODO_;                     break;
          case R_X86_64_TLSDESC:         TODO_;                     break;
          case R_X86_64_IRELATIVE:       TODO_;                     break;
          case R_X86_64_RELATIVE64:      TODO_;                     break;
          case R_X86_64_GOTPCRELX:       ADD_(32, GOT + G + A - P); break;
          case R_X86_64_REX_GOTPCRELX:   ADD_(32, GOT + G + A - P); break;

          default: FAIL("Unknown relocation type", 0);

          #undef ADD_
          #undef TODO_
        }
      }
    }

    sec_index_global += num_sections - 1;
  }

  //  ==============================================================
  //
  //  Apply internal relocations

  #define FIND_(x)                                                              \
    do {                                                                        \
      Link_Sym_Entry *symbols_ = CHUNK(pool, linker->symbols,  Link_Sym_Entry); \
      CHECK(symbols_ != NULL, "Internal", 0);                                   \
      for (i64 i = 0; i < num_symbols; ++i)                                     \
        if (STR_EQ(symbols_[i].name_size, symbols_[i].name, #x)) {              \
          LOG(INFO, "Found " #x ": 0x%llx", symbols_[i].address);               \
          break;                                                                \
        }                                                                       \
    } while (0)

  FIND_(_start);
  FIND_(__libc_start_main);
  FIND_(__tunables_init);
  FIND_(__libc_early_init);
  FIND_(__ctype_init);

  #undef FIND_

  i64 num_rels = codegen->rels.size / sizeof(Codegen_Rel_Entry);
  Codegen_Rel_Entry *rels = CHUNK(pool, codegen->rels, Codegen_Rel_Entry);
  CHECK(rels != NULL, "Internal", 0);

  for (i64 rel_index = 0; rel_index < num_rels; ++rel_index) {
    Codegen_Rel_Entry rel = rels[rel_index];

    u8 *buffer_code = CHUNK(pool, codegen->buffer_code, u8);
    CHECK(buffer_code != NULL, "Internal", 0);

    u8 *begin = buffer_code + rel.offset;
    u8 *end   = buffer_code + codegen->offset_code;

    switch (rel.type) {
      case REL_ADD_INSTRUCTION_ADDRESS: {
        CHECK(rel.size == 8, "Not implemented", 0);
        i64 value = rel.value + rx_code_address + rel.offset;
        write_i64(LE, value, begin, end);
      } break;

      case REL_ADD_RO_OP_ADDRESS: {
        CHECK(rel.size == 8, "Not implemented", 0);
        i64 value = rel.value + ro_data_address;
        write_i64(LE, value, begin, end);
      } break;

      case REL_ADD_PROC_ADDRESS: {
        CHECK(rel.size == 8, "Not implemented", 0);

        b8 found = 0;

        if (rel.proc == UNDEFINED) {
          CHECK(rel.name_size > 0 && rel.name != NULL, "No proc name", 0);

          Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols,  Link_Sym_Entry);
          CHECK(symbols != NULL, "Internal", 0);

          for (i64 i = 0; i < num_symbols; ++i)
            if (symbols[i].address != 0      &&
                str_eq(symbols[i].name_size,
                       symbols[i].name,
                       rel.name_size, rel.name)) {
              i64 value = rel.value + symbols[i].address;
              write_i64(LE, value, begin, end);
              found = 1;

              LOG(VERBOSE, "Found %.*s: 0x%llx", rel.name_size, rel.name, value);
              break;
            }
        } else {
          i64     num_entities = pool->entities.size / sizeof(Entity);
          Entity *entities     = CHUNK(pool, pool->entities, Entity);

          Codegen_Entity *codegen_entities = CHUNK(pool, codegen->entities, Codegen_Entity);
          CHECK(codegen_entities != NULL, "Internal", 0);

          CHECK(rel.proc != UNDEFINED, "Undefined", 0);
          CHECK(rel.proc > 0 && rel.proc < num_entities, "Buffer overflow", 0);
          CHECK(entities != NULL, "Internal", 0);
          CHECK(entities[rel.proc].is_enabled,          "No entity", 0);
          CHECK(entities[rel.proc].type == ENTITY_PROC, "No proc", 0);
          CHECK(codegen_entities[rel.proc].emit_done,   "No proc address", 0);

          i64 value = rel.value + rx_code_address + codegen_entities[rel.proc].offset;
          write_i64(LE, value, begin, end);
          found = 1;

          LOG(VERBOSE, "Found anonymous proc: 0x%llx", value);
        }

        if (!found) {
          LOG(ERROR, "Undefined symbol: %.*s", rel.name_size, rel.name);
          FAIL("Link failed", 0);
        }
      } break;
    }
  }

  //  ==============================================================
  //
  //  Writing the ELF executable
  //

  i64 output_size = align(rw_tls_data_offset + rw_tls_data_size, X86_64_PAGE_SIZE);

  i64 entry = rx_code_address + codegen->entry_point;

  if (!codegen->has_entry) {
    //  TODO Explicitly declare _start proc

    b8 found = 0;

    Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols,  Link_Sym_Entry);
    CHECK(symbols != NULL, "Internal", 0);

    for (i64 sym_index = 0; sym_index < num_symbols; ++sym_index)
      if (STR_EQ(symbols[sym_index].name_size, symbols[sym_index].name, "_start")) {
          entry = symbols[sym_index].address;
          found = 1;
          break;
        }

    CHECK(found, "Undefined symbol: _start", 0);
  }

  LOG(VERBOSE, "Entry point: 0x%llx", entry);

  LOG(VERBOSE, "Total %lld sections", num_sections_total);
  LOG(VERBOSE, "Total %lld symbols",  num_symbols);

  LOG(VERBOSE, "Total size");
  LOG(VERBOSE, "r/x code     - %7lld bytes", rx_code_size);
  LOG(VERBOSE, "r/o data     - %7lld bytes", ro_data_size);
  LOG(VERBOSE, "r/w data     - %7lld bytes", rw_data_size);
  LOG(VERBOSE, "r/w zval     - %7lld bytes", rw_zval_size);
  LOG(VERBOSE, "r/w TLS data - %7lld bytes", rw_tls_data_size);
  LOG(VERBOSE, "r/w TLS zval - %7lld bytes", rw_tls_zval_size);
  LOG(VERBOSE, "r/w GOT      - %7lld bytes", rw_got_size);
  LOG(VERBOSE, "r/w dynamic  - %7lld bytes", rw_dynamic_size);

  LOG(VERBOSE, "Writing ELF x86_64 executable");

  linker->output_buffer = chunk_resize(pool, linker->output_buffer, output_size);

  u8 *o     = CHUNK(pool, linker->output_buffer, u8);
  u8 *o_end = o + linker->output_buffer.size;

  //  ELF header
  //

  mem_cpy(o, ELF_MAGIC, 4);

  write_u8 (LE, ELF_64,                  o +   4, o_end);
  write_u8 (LE, ELF_2_LE,                o +   5, o_end);
  write_u8 (LE, ELF_VERSION,             o +   6, o_end);
  write_u8 (LE, ELF_SYS_V,               o +   7, o_end);
  write_u8 (LE, ELF_ABI_VERSION,         o +   8, o_end);
  // 7 bytes - padding
  write_u16(LE, ELF_EXECUTABLE,          o +  16, o_end);
  write_u16(LE, ELF_X86_64,              o +  18, o_end);
  write_u32(LE, ELF_VERSION,             o +  20, o_end);
  write_i64(LE, entry,                   o +  24, o_end);
  write_u64(LE, ELF_HEADER_SIZE,         o +  32, o_end); // program header offset
  // 8 bytes - section header offset     o +  40
  // 4 bytes - flags                     o +  48
  write_u16(LE, ELF_HEADER_SIZE,         o +  52, o_end);
  write_u16(LE, ELF_PROGRAM_HEADER_SIZE, o +  54, o_end);
  // write_u16(LE, num_program_headers,     o +  56, o_end);
  // 2 bytes - section header size       o +  58
  // 2 bytes - num section headers       o +  60
  // 2 bytes - string table section      o +  62
  //           header index

  //  Program headers
  //

  CHECK(rx_code_offset     % X86_64_PAGE_SIZE == rx_code_address     % X86_64_PAGE_SIZE, "Invalid alignment", 0);
  CHECK(rw_data_offset     % X86_64_PAGE_SIZE == rw_data_address     % X86_64_PAGE_SIZE, "Invalid alignment", 0);
  CHECK(ro_data_offset     % X86_64_PAGE_SIZE == ro_data_address     % X86_64_PAGE_SIZE, "Invalid alignment", 0);
  CHECK(rw_got_offset      % X86_64_PAGE_SIZE == rw_got_address      % X86_64_PAGE_SIZE, "Invalid alignemtn", 0);
  CHECK(rw_dynamic_offset  % X86_64_PAGE_SIZE == rw_dynamic_address  % X86_64_PAGE_SIZE, "Invalid alignemtn", 0);
  CHECK(rw_tls_data_offset % X86_64_PAGE_SIZE == rw_tls_data_address % X86_64_PAGE_SIZE, "Invalid alignment", 0);

  u8 *h = o + ELF_HEADER_SIZE;

  num_program_headers = 0;

  //  r/x code
  if (rx_code_size > 0) {
    write_u32(LE, 1,                h,      o_end); // type   (PT_LOAD)
    write_u32(LE, 5,                h +  4, o_end); // flags  (PF_X | PF_R)
    write_i64(LE, rx_code_offset,   h +  8, o_end);
    write_i64(LE, rx_code_address,  h + 16, o_end); // virtual address
    write_i64(LE, rx_code_address,  h + 24, o_end); // phisical address
    write_i64(LE, rx_code_size,     h + 32, o_end); // size in file
    write_i64(LE, rx_code_size,     h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT, h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/o data
  if (ro_data_size > 0) {
    write_u32(LE, 1,                h,      o_end); // type   (PT_LOAD)
    write_u32(LE, 4,                h +  4, o_end); // flags  (PF_R)
    write_i64(LE, ro_data_offset,   h +  8, o_end);
    write_i64(LE, ro_data_address,  h + 16, o_end); // virtual address
    write_i64(LE, ro_data_address,  h + 24, o_end); // phisical address
    write_i64(LE, ro_data_size,     h + 32, o_end); // size in file
    write_i64(LE, ro_data_size,     h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT, h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w data
  if (rw_data_size > 0) {
    write_u32(LE, 1,                h,      o_end); // type   (PT_LOAD)
    write_u32(LE, 6,                h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, rw_data_offset,   h +  8, o_end);
    write_i64(LE, rw_data_address,  h + 16, o_end); // virtual address
    write_i64(LE, rw_data_address,  h + 24, o_end); // phisical address
    write_i64(LE, rw_data_size,     h + 32, o_end); // size in file
    write_i64(LE, rw_data_size,     h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT, h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w zero values
  if (rw_zval_size > 0) {
    write_u32(LE, 1,                h,      o_end); // type   (PT_LOAD)
    write_u32(LE, 6,                h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, rw_got_offset,    h +  8, o_end);
    write_i64(LE, rw_zval_address,  h + 16, o_end); // virtual address
    write_i64(LE, rw_zval_address,  h + 24, o_end); // phisical address
    write_i64(LE, 0,                h + 32, o_end); // size in file
    write_i64(LE, rw_zval_size,     h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT, h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w GOT
  if (rw_got_size > 0) {
    write_u32(LE, 1,                h,      o_end); // type   (PT_LOAD)
    write_u32(LE, 6,                h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, rw_got_offset,    h +  8, o_end);
    write_i64(LE, rw_got_address,   h + 16, o_end); // virtual address
    write_i64(LE, rw_got_address,   h + 24, o_end); // phisical address
    write_i64(LE, rw_got_size,      h + 32, o_end); // size in file
    write_i64(LE, rw_got_size,      h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT, h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w dynamic
  if (rw_dynamic_size) {
    write_u32(LE, 2,                  h,      o_end); // type   (PT_DYNAMIC)
    write_u32(LE, 6,                  h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, rw_dynamic_offset,  h +  8, o_end);
    write_i64(LE, rw_dynamic_address, h + 16, o_end); // virtual address
    write_i64(LE, rw_dynamic_address, h + 24, o_end); // phisical address
    write_i64(LE, rw_dynamic_size,    h + 32, o_end); // size in file
    write_i64(LE, rw_dynamic_size,    h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT,   h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w TLS data
  if (rw_tls_data_size > 0) {
    write_u32(LE, 7,                   h,      o_end); // type   (PT_TLS)
    write_u32(LE, 6,                   h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, rw_tls_data_offset,  h +  8, o_end);
    write_i64(LE, rw_tls_data_address, h + 16, o_end); // virtual address
    write_i64(LE, rw_tls_data_address, h + 24, o_end); // phisical address
    write_i64(LE, rw_tls_data_size,    h + 32, o_end); // size in file
    write_i64(LE, rw_tls_data_size,    h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT,    h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  //  r/w TLS zero values
  if (rw_tls_zval_size > 0) {
    write_u32(LE, 7,                   h,      o_end); // type   (PT_TLS)
    write_u32(LE, 6,                   h +  4, o_end); // flags  (PF_R | PF_W)
    write_i64(LE, output_size,         h +  8, o_end);
    write_i64(LE, rw_tls_zval_address, h + 16, o_end); // virtual address
    write_i64(LE, rw_tls_zval_address, h + 24, o_end); // phisical address
    write_i64(LE, 0,                   h + 32, o_end); // size in file
    write_i64(LE, rw_tls_zval_size,    h + 40, o_end); // size in memory
    write_i64(LE, X86_64_ALIGNMENT,    h + 48, o_end);
    h += ELF_PROGRAM_HEADER_SIZE;
    ++num_program_headers;
  }

  write_u16(LE, num_program_headers, o + 56, o_end);

  CHECK(h == o + ELF_HEADER_SIZE + num_program_headers * ELF_PROGRAM_HEADER_SIZE, "Invalid num program headers", 0);
  CHECK(rx_code_offset >= h - o, "Sanity", 0);

  //  Code
  //

  u8 *buffer_code    = CHUNK(pool, codegen->buffer_code, u8);
  u8 *buffer_ro_data = CHUNK(pool, codegen->buffer_ro_data, u8);

  CHECK(buffer_code != NULL,    "Internal", 0);
  CHECK(buffer_ro_data != NULL, "Internal", 0);

  mem_cpy(o + rx_code_offset, buffer_code,    codegen->offset_code);
  mem_cpy(o + ro_data_offset, buffer_ro_data, codegen->offset_ro_data);

  //  ==============================================================
  //
  //  Write sections into the output buffer

  Link_Sec_Entry *sections = CHUNK(pool, linker->sections, Link_Sec_Entry);
  CHECK(sections != NULL, "Internal", 0);

  for (i64 elf_index = 0, sec_index_global = 0; elf_index < linker->num_obj_files; ++elf_index) {
    Buffer_Context buf     = elf_buffer_context(pool, linker, linker->num_obj_files, elf_index);
    Offset_Num     headers = elf_section_headers(buf);

    for (i64 sec_index = 1; sec_index < headers.num; ++sec_index, ++sec_index_global) {
      Elf_Section_Header section = elf_section(buf, sec_index);
      i64                offset  = sections[sec_index_global].offset;
      if (offset == 0            ||
          !section.alloc         ||
          section.data.size == 0)
        continue;
      u8 *p = o + offset;
      CHECK(p                     >= o + program_offset + codegen->offset_code, "Buffer overflow", 0);
      CHECK(p + section.data.size <= o + output_size,                           "Buffer overflow", 0);
      mem_cpy(p, buf.begin + section.data.offset, section.data.size);
    }
  }

  //  GOT

  write_u64(LE, rw_dynamic_address, o + rw_got_offset, o_end);

  Link_Sym_Entry *symbols = CHUNK(pool, linker->symbols, Link_Sym_Entry);
  CHECK(symbols != NULL, "Internal", 0);

  for (i64 i = 0, offset = 0; i < num_symbols; ++i) {
    Link_Sym_Entry *sym = symbols + i;
    if (sym->got_offset == 0)
      continue;

    offset += ELF_GOT_ENTRY_SIZE;
    CHECK(offset < rw_got_size, "Sanity", 0);
    write_u64(LE, sym->address, o + rw_got_offset + offset, o_end);
  }

  //  ==============================================================

  return output_size;
}

b8 unit_write_with_context(
  Pool *           pool,
  Codegen_Context *codegen,
  Linker_Context * linker,
  i64              unit,
  u16              format,
  u16              arch,
  i64              io_out,
  void *           io_user_data
) {
  CHECK(unit != UNDEFINED, "Invalid unit", 0);

  //  ==============================================================
  //
  //  Reading dependencies

  i64 obj_files_size = 0;

  Unit *u = unit_by_id(pool, unit);

  i64  num_links = u->links.size / sizeof(i64);
  i64 *links     = CHUNK(pool, u->links, i64);
  CHECK(links != NULL, "Internal", 0);

  for (i64 link_index = 1; link_index < num_links; ++link_index) {
    i64 id = links[link_index];
    if (id == UNDEFINED)
      continue;
    Unit *l = unit_by_id(pool, id);
    CHECK(entity_enabled(pool, id), "Internal", 0);
    CHECK(l->name.size > 0,         "No link name", 0);

    switch (l->type) {
      case UNIT_LIBRARY_OBJECT: {
        i64 f = io_open_read(l->name.size, CHUNK(pool, l->name, c8), io_user_data);
        io_seek(f, 0, IO_SEEK_END, io_user_data);

        i64 in_size = io_tell(f, io_user_data);

        linker->dependencies_buffer = chunk_resize(pool, linker->dependencies_buffer, obj_files_size + in_size);
        u8 *dependencies_buffer = CHUNK(pool, linker->dependencies_buffer, u8);
        CHECK(dependencies_buffer != NULL, "Internal", 0);

        io_seek(f, 0, IO_SEEK_BEGIN, io_user_data);
        i64 n = io_read(f, in_size, dependencies_buffer + obj_files_size, io_user_data);
        CHECK(n == in_size, "Read failed", 0);

        io_close(f, io_user_data);

        linker->obj_file_offsets = chunk_resize(pool, linker->obj_file_offsets, (linker->num_obj_files + 2) * sizeof(i64));
        i64 *obj_file_offsets = CHUNK(pool, linker->obj_file_offsets, i64);
        CHECK(obj_file_offsets != NULL, "Internal", 0);

        obj_file_offsets[linker->num_obj_files]   = obj_files_size;
        obj_files_size                          += align(in_size, X86_64_ALIGNMENT);
        obj_file_offsets[++linker->num_obj_files] = obj_files_size;
      } break;

      case UNIT_LIBRARY_STATIC: {
        i64 f = io_open_read(l->name.size, CHUNK(pool, l->name, c8), io_user_data);
        io_seek(f, 0, IO_SEEK_END, io_user_data);

        i64 in_size = io_tell(f, io_user_data);

        linker->obj_file_buffer = chunk_resize(pool, linker->obj_file_buffer, in_size);
        u8 *obj_file_buffer = CHUNK(pool, linker->obj_file_buffer, u8);
        CHECK(obj_file_buffer != NULL, "Internal", 0);

        io_seek(f, 0, IO_SEEK_BEGIN, io_user_data);
        i64 n = io_read(f, in_size, obj_file_buffer, io_user_data);
        CHECK(n == in_size, "Read failed", 0);

        io_close(f, io_user_data);

        //  ========================================================
        //
        //  Read AR library

        u8 *ar_begin = obj_file_buffer;
        u8 *ar_end   = obj_file_buffer + in_size;

        CHECK(mem_eq(ar_begin, AR_MAGIC, 8), "Invalid AR file", 0);

        u8 *f_begin = ar_begin + 8;

        while (f_begin + 60 < ar_end) {
          u8 *f_id   = f_begin;
          u8 *f_size = f_begin + 48;
          u8 *f_end  = f_begin + 58;
          u8 *f_data = f_begin + 60;

          i64 size = (i64) u64_from_dec_str((c8 *) f_size, (c8 *) f_size + 10);

          size = align(size, 2);

          CHECK(mem_eq(f_end, "\x60\x0a", 2), "Invalid AR file", 0);
          CHECK(f_begin + size <= ar_end,     "Buffer overflow", 0);

          if (!mem_eq(f_id, AR_SYMBOL_TABLE, sizeof AR_SYMBOL_TABLE - 1) &&
              !mem_eq(f_id, AR_STRING_TABLE, sizeof AR_STRING_TABLE - 1)) {
            //  Read ELF object file

            i64 delta_size = align(size, X86_64_ALIGNMENT);

            u8 *dependencies_buffer = CHUNK(pool, linker->dependencies_buffer, u8);
            CHECK(dependencies_buffer != NULL, "Internal", 0);

            mem_cpy(dependencies_buffer + obj_files_size, f_data, size);

            i64 *obj_file_offsets = CHUNK(pool, linker->obj_file_offsets, i64);
            CHECK(obj_file_offsets != NULL, "Internal", 0);

            obj_file_offsets[linker->num_obj_files]   = obj_files_size;
            obj_files_size                          += delta_size;
            obj_file_offsets[++linker->num_obj_files] = obj_files_size;
          }

          f_begin = f_data + size;
        }
      } break;

      default:
        FAIL("Not implemented", 0);
    }
  }

  //  ==============================================================

  i64 output_size = unit_write_in_memory(pool, codegen, linker, unit, format, arch);

  if (output_size <= 0)
    return 0;

  //  ==============================================================
  //
  //  Write the output buffer into the file

  u8 *output_buffer = CHUNK(pool, linker->output_buffer, u8);
  CHECK(output_buffer != NULL, "Internal", 0);

  io_write(io_out, output_size, output_buffer, io_user_data);

  return 1;
}

b8 unit_write(
  Pool *           pool,
  i64              unit,
  u16              format,
  u16              arch,
  i64              io_out,
  void *           io_user_data
) {
  Codegen_Context codegen = {0};
  Linker_Context  linker  = {0};

  b8 status = unit_write_with_context(pool, &codegen, &linker, unit, format, arch, io_out, io_user_data);

  chunk_remove(pool, codegen.entities);
  chunk_remove(pool, codegen.rels);
  chunk_remove(pool, codegen.buffer_code);
  chunk_remove(pool, codegen.buffer_ro_data);

  chunk_remove(pool, linker.obj_file_buffer);
  chunk_remove(pool, linker.dependencies_buffer);
  chunk_remove(pool, linker.obj_file_offsets);
  chunk_remove(pool, linker.sections);
  chunk_remove(pool, linker.symbols);
  chunk_remove(pool, linker.rels);
  chunk_remove(pool, linker.output_buffer);

  return status;
}

i64 io_open_read(i64 name_size, c8 *name, void *user_data) {
  i64 f;
  dispatch_io(IO_OPEN_READ, &f, &name_size, name, user_data);
  return f;
}

i64 io_open_write(i64 name_size, c8 *name, void *user_data) {
  i64 f;
  dispatch_io(IO_OPEN_WRITE, &f, &name_size, name, user_data);
  return f;
}

void io_close(i64 f, void *user_data) {
  dispatch_io(IO_CLOSE, &f, NULL, NULL, user_data);
}

b8 io_seek(i64 f, i64 offset, u16 origin, void *user_data) {
  dispatch_io(IO_SEEK, &f, &offset, &origin, user_data);
  return 1;
}

i64 io_tell(i64 f, void *user_data) {
  i64 offset;
  dispatch_io(IO_TELL, &f, &offset, NULL, user_data);
  return offset;
}

i64 io_read(i64 f, i64 size, void *data, void *user_data) {
  dispatch_io(IO_READ, &f, &size, data, user_data);
  return size;
}

i64 io_write(i64 f, i64 size, void *data, void *user_data) {
  dispatch_io(IO_WRITE, &f, &size, data, user_data);
  return size;
}

void io_chmod_exe(i64 f, void *user_data) {
  dispatch_io(IO_CHMOD_EXE, &f, NULL, NULL, user_data);
}

//  ================================================================
//
//  * Helper procedures
//
//  ================================================================

#if HELPERS

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

#ifdef __unix__
#include <sys/types.h>
#include <sys/stat.h>
#endif

void wait_any_input(void) {
  while (getc(stdin) != '\n');
  fflush(stdin);
}

void dispatch_assert(b8 condition, c8 *message, u32 line, c8 *file) {
  if (condition)
    return;

  dispatch_log(ERROR, line, file, message);
  exit(-1);
}

void dispatch_log(i32 log_level, u32 line, c8 *file, c8 *format, ...) {
  if (file == NULL || format == NULL)
    return;

  if (*format == '\0' && log_level != TRACE) {
    fprintf(log_level == ERROR || log_level == WARNING ? stderr : stdout, "\n");
    return;
  }

  c8 message[256] = {0};

  va_list ap;
  va_start(ap, format);
  vsnprintf(message, sizeof message, format, ap);
  va_end(ap);

  fflush(stdout);
  i32 len = 56 - (i32) str_len_or(message, message + 56, 56);
  switch (log_level) {
    case ERROR:
      fprintf(stderr,
              "\r\x1b[41;1m\x1b[30m Error   \x1b[40;0m\x1b[37m %s "
              "%.*s \x1b[36m%s\x1b[34m:%d\x1b[37m\n",
              message, len,
              "................................................................",
              file, line);
      if (LOG_BLOCKING)
        wait_any_input();
      break;

    case WARNING:
      fprintf(stderr,
              "\r\x1b[43;1m\x1b[30m Warning \x1b[40;0m\x1b[37m %s "
              "%.*s \x1b[36m%s\x1b[34m:%d\x1b[37m\n",
              message, len,
              "................................................................",
              file, line);
      if (LOG_BLOCKING)
        wait_any_input();
      break;

    case INFO:
      fprintf(stdout,
              "\r\x1b[42;1m\x1b[30m Info    \x1b[40;0m\x1b[37m %s\n",
              message);
      break;

    case VERBOSE:
      fprintf(stdout,
              "\r\x1b[47;1m\x1b[30m Verbose \x1b[40;0m\x1b[37m %s\n",
              message);
      break;

    case TRACE:
      fprintf(stdout,
              "\r\x1b[45;1m\x1b[30m Trace   \x1b[40;0m\x1b[37m %s "
              "%.*s \x1b[36m%s\x1b[34m:%d\x1b[37m\n",
              message, len,
              "................................................................",
              file, line);
      if (TRACE_BLOCKING)
        wait_any_input();
      break;

    default:;
  }
}

//  IO dispatch procedure
//

void dispatch_io(u16 op, i64 *id, i64 *size, void *data, void *user_data) {
  CHECK(id != NULL, "Sanity",);

  (void) user_data;

  FILE **f             = (FILE **) id;
  c8     buf[1024 * 4] = { 0 };

  switch (op) {
    case IO_OPEN_READ:
    case IO_OPEN_WRITE:
      CHECK(size != NULL,                          "Sanity",);
      CHECK(*size > 0 && *size < (i64) sizeof buf, "Sanity",);
      CHECK(data != NULL,                          "Sanity",);

      mem_cpy(buf, data, *size);
      *f = fopen(buf, op == IO_OPEN_READ ? "rb" : "wb");
      if (*f == NULL)
        LOG(ERROR, "Open: %s", buf);
      CHECK(*f != NULL, "File open failed",);
      break;

    case IO_CLOSE:
      CHECK(*f != NULL,   "Sanity",);
      CHECK(size == NULL, "Sanity",);
      CHECK(data == NULL, "Sanity",);

      fclose(*f);
      break;

    case IO_SEEK: {
      CHECK(*f != NULL,   "Sanity",);
      CHECK(size != NULL, "Sanity",);
      CHECK(data != NULL, "Sanity",);

      u16 *origin = (u16 *) data;

      if (!(*origin == IO_SEEK_CURSOR && *size == 0)) {
        CHECK(*origin == IO_SEEK_CURSOR ||
                 *origin == IO_SEEK_BEGIN  ||
                 *origin == IO_SEEK_END, "Sanity",);
        i32 s = fseek(*f, *size,
                      *origin == IO_SEEK_CURSOR ? SEEK_CUR :
                      *origin == IO_SEEK_BEGIN  ? SEEK_SET :
                                                  SEEK_END);
        CHECK(s == 0, "File seek failed",);
      }
    } break;

    case IO_TELL: {
        CHECK(*f != NULL,   "Sanity",);
        CHECK(size != NULL, "Sanity",);
        CHECK(data == NULL, "Sanity",);

        i64 n = (i64) ftell(*f);
        CHECK(n >= 0, "File tell failed",);

        *size = n;
    } break;

    case IO_READ:
      CHECK(*f != NULL,   "Sanity",);
      CHECK(size != NULL, "Sanity",);
      CHECK(data != NULL, "Sanity",);
      CHECK(*size > 0,    "Sanity",);

      *size = fread(data, 1, *size, *f);
      break;

    case IO_WRITE:
      CHECK(*f != NULL,   "Sanity",);
      CHECK(size != NULL, "Sanity",);
      CHECK(data != NULL, "Sanity",);
      CHECK(*size > 0,    "Sanity",);

      *size = fwrite(data, 1, *size, *f);
      break;

    case IO_CHMOD_EXE:
      CHECK(*f != NULL,   "Sanity",);
      CHECK(size == NULL, "Sanity",);

#ifdef __unix__
      fchmod(fileno(*f), 0775);
#endif
      break;

    default:
      FAIL("Sanity",);
  }
}

//  Global state
//

Pool g_pool = {
  //  Statically allocate a large memory block.
  //  TODO Reallocate the memory block when necessary.

  .capacity = POOL_CAPACITY,
  .data     = (u8[POOL_CAPACITY]) {0},
};

//  Handy procedures
//

i64 n_ref(i64 proc, i64 node) {
  i64 n_ref = node_data_reference(&g_pool, node);
  p_add(proc, n_ref);
  return n_ref;
}

i64 n_ptr(i64 proc, u64 address) {
  i64 n_data = node_data_ptr(&g_pool, address);
  p_add(proc, n_data);
  return n_data;
}

i64 n_str(i64 proc, c8 *value) {
  i64 len    = str_len(value, value + MAX_STRING_SIZE - 1);
  i64 n_data = node_data_array_c8(&g_pool, len + 1, value);
  i64 n_ref  = node_data_reference(&g_pool, n_data);
  p_add(proc, n_data);
  p_add(proc, n_ref);
  return n_ref;
}

i64 n_i32(i64 proc, i32 value) {
  i64 n = node_data_i32(&g_pool, value);
  p_add(proc, n);
  return n;
}

i64 n_i64(i64 proc, i64 value) {
  i64 n = node_data_i64(&g_pool, value);
  p_add(proc, n);
  return n;
}

i64 n_add(i64 proc, Var x, Var y) {
  i64 n = node_data_add(&g_pool, x, y);
  p_add(proc, n);
  return n;
}

i64 n_sub(i64 proc, Var x, Var y) {
  i64 n = node_data_sub(&g_pool, x, y);
  p_add(proc, n);
  return n;
}

i64 n_call(i64 proc, i64 ctrl_previous, i64 ctrl_index, i64 target_proc, i64 num_args, Var *args) {
  i64 n = node_ctrl_call(&g_pool, ctrl_previous, ctrl_index, target_proc, num_args, args);
  p_add(proc, n);
  return n;
}

i64 n_call_by_name(i64 proc, i64 ctrl_previous, i64 ctrl_index, c8 *name, i64 num_args, Var *args) {
  i64 n = node_ctrl_call_by_name(&g_pool, ctrl_previous, ctrl_index, str_len(name, name + MAX_STRING_SIZE), name, num_args, args);
  p_add(proc, n);
  return n;
}

i64 n_if(i64 proc, i64 ctrl_previous, i64 ctrl_index, Var condition) {
  i64 n = node_ctrl_if(&g_pool, ctrl_previous, ctrl_index, condition);
  p_add(proc, n);
  return n;
}

i64 n_ret(i64 proc, i64 ctrl_previous, i64 ctrl_index, i64 num_vals, Var *vals) {
  i64 n = node_ctrl_ret(&g_pool, ctrl_previous, ctrl_index, num_vals, vals);
  p_add(proc, n);
  return n;
}

i64 p_new(i64 unit, c8 *name) {
  i64 p   = proc_init(&g_pool);
  i64 len = str_len(name, name + MAX_STRING_SIZE);
  if (len > 0)
    proc_set_name(&g_pool, p, len, name);
  u_add(unit, p);
  return p;
}

i64 p_new_entry(i64 unit) {
  i64 p = p_new(unit, "");
  u_entry_point(unit, p);
  return p;
}

void p_add(i64 proc, i64 node) {
  proc_node_add(&g_pool, proc, node);
}

i64 u_new(void) {
  return unit_init(&g_pool, UNIT_CODE);
}

void u_add(i64 unit, i64 proc) {
  unit_proc_add(&g_pool, unit, proc);
}

void u_entry_point(i64 unit, i64 proc) {
  unit_set_entry_point(&g_pool, unit, proc);
}

void u_elf_x86_64(i64 unit, c8 *output_file_name) {
  i64 name_len = str_len(output_file_name, output_file_name + MAX_STRING_SIZE);
  i64 out      = io_open_write(name_len, output_file_name, NULL);

  b8 ok = unit_write(&g_pool, unit, FORMAT_ELF, ARCH_X86_64, out, NULL);

  io_chmod_exe(out, NULL);
  io_close(out, NULL);

  CHECK(ok, "Failed",);
}

void l_code(i64 unit, i64 link_unit) {
  unit_link_add(&g_pool, unit, link_unit);
}

void l_object(i64 unit, c8 *object_library) {
  i64 l    = unit_init(&g_pool, UNIT_LIBRARY_OBJECT);
  c8 *path = l_find(object_library, 0);
  i64 len  = str_len(path, path + MAX_STRING_SIZE);
  unit_set_name(&g_pool, l, len, path);
  unit_link_add(&g_pool, unit, l);
}

void l_static(i64 unit, c8 *static_library) {
  i64 l    = unit_init(&g_pool, UNIT_LIBRARY_STATIC);
  c8 *path = l_find(static_library, 0);
  i64 len  = str_len(path, path + MAX_STRING_SIZE);
  unit_set_name(&g_pool, l, len, path);
  unit_link_add(&g_pool, unit, l);
}

c8 *l_find(c8 *name, b8 silent) {
  //  Find the full path to a library

  //  FIXME: This does not take into account cross-compilation.

  CHECK(name != NULL, "Invalid argument", "");

  i64 len = str_len(name, name + MAX_STRING_SIZE);

  CHECK(len < MAX_STRING_SIZE, "Invalid argument", "");

  static c8 buf[MAX_STRING_SIZE]; // FIXME

  #define TRY_(template)                           \
    do {                                           \
      snprintf(buf, sizeof buf, (template), name); \
      FILE *f = fopen(buf, "rb");                  \
      if (f == NULL) break;                        \
      fclose(f);                                   \
      if (!silent)                                 \
        LOG(VERBOSE, "Found library: %s", buf);    \
      return buf;                                  \
    } while (0)

  TRY_("%s");

  if (HOST_OS == OS_Linux) {
    TRY_("/lib/%s");

    if (HOST_ARCH == ARCH_X86_64 || HOST_ARCH == ARCH_ARM64)
      TRY_("/lib64/%s");

    if (HOST_ARCH == ARCH_X86_64)
      TRY_("/lib/x86_64-linux-gnu/%s");
  }

  TRY_("lib%s.a");
  TRY_("%s.o");

  if (HOST_OS == OS_Linux) {
    TRY_("/lib/lib%s.a");
    TRY_("/lib/%s.o");

    if (HOST_ARCH == ARCH_X86_64 || HOST_ARCH == ARCH_ARM64) {
      TRY_("/lib64/lib%s.a");
      TRY_("/lib64/%s.o");
    }

    if (HOST_ARCH == ARCH_X86_64) {
      TRY_("/lib/x86_64-linux-gnu/lib%s.a");
      TRY_("/lib/x86_64-linux-gnu/%s.o");
    }
  }

  #undef TRY_

  FAIL("Library not found", "");
}

#endif

//  ================================================================
//
//    TEST SUITE
//
//  ================================================================

#if TESTING

#if HELPERS

#define ADD_TEST_(name_, res_, ...)                       \
  b8 name_(void) {                                        \
    i64 u = u_new();                                      \
    CHECK(u != UNDEFINED, "Sanity", 0);                   \
                                                          \
    __VA_ARGS__                                           \
                                                          \
    u_elf_x86_64(u, "test_" #name_);                      \
                                                          \
    b8 success = 1;                                       \
                                                          \
    if (HOST_OS != OS_Linux) {                            \
      LOG(INFO, "Skip running the executable. "           \
                "Host system is not compatible.");        \
    } else if (HO != LE) {                                \
      LOG(INFO, "Skip running the executable. "           \
                "Host data ordering is not compatible."); \
    } else {                                              \
      LOG(VERBOSE, "Running the executable");             \
                                                          \
      i32 ret;                                            \
                                                          \
      if (LOG_LEVEL >= VERBOSE)                           \
        ret = system("./test_" #name_);                   \
      else                                                \
        ret = system("./test_" #name_ " >/dev/null");     \
                                                          \
      if (WEXITSTATUS(ret) != res_)                       \
        success = 0;                                      \
    }                                                     \
                                                          \
    if (success)                                          \
      system("rm test_" #name_);                          \
                                                          \
    return success;                                       \
  }

ADD_TEST_(link_with_libc, 42,
  //  Add the main proc.
  i64 p = p_new(u, "main");
  {
    //  Call puts
    N_CALL_BY_NAME(
      p,
      0, 0,
      "puts",                         // proc name
      n_str(p, "hello sailor") // the first argument
    );

    //  Return 42
    N_RET(
      p,
      0, 0,
      n_i32(p, 42) // the return value
    );
  }

  //  Add dependencies

  if (l_find("c_nonshared", 1)[0] != '\0')
    l_static(u, "c_nonshared");
  else
    l_static(u, "c");
  l_object(u, "crt1");
)

ADD_TEST_(math_two_plus_two, 4,
  i64 p = p_new_entry(u);

  N_RET(
    p,
    0, 0,
    n_add(p, n_i32(p, 2), n_i32(p, 2))
  );
)

ADD_TEST_(math_sixty_nine, 69,
  i64 p = p_new_entry(u);

  N_RET(
    p,
    0, 0,
    n_add(p, n_i32(p, 27), n_i32(p, 42))
  );
)

ADD_TEST_(math_add_3, 1+2+3,
  i64 p = p_new_entry(u);

  i64 a = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b = n_i32(p, 3);

  N_RET(
    p,
    0, 0,
    n_add(p, a, b)
  );
)

ADD_TEST_(math_add_4a, 1+2+3+4,
  i64 p = p_new_entry(u);

  i64 a = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b = n_add(p, n_i32(p, 3), n_i32(p, 4));

  N_RET(
    p,
    0, 0,
    n_add(p, a, b)
  );
)

ADD_TEST_(math_add_5, 1+2+3+4+5,
  i64 p = p_new_entry(u);

  i64 a   = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b   = n_add(p, n_i32(p, 3), n_i32(p, 4));
  i64 c   = n_i32(p, 5);
  i64 a_b = n_add(p, a, b);

  N_RET(
    p,
    0, 0,
    n_add(p, a_b, c)
  );
)

ADD_TEST_(math_add_6, 1+2+3+4+5+6,
  i64 p = p_new_entry(u);

  i64 a   = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b   = n_add(p, n_i32(p, 3), n_i32(p, 4));
  i64 c   = n_add(p, n_i32(p, 5), n_i32(p, 6));
  i64 a_b = n_add(p, a, b);

  N_RET(
    p,
    0, 0,
    n_add(p, a_b, c)
  );
)

ADD_TEST_(math_add_7, 1+2+3+4+5+6+7,
  i64 p = p_new_entry(u);

  i64 a   = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b   = n_add(p, n_i32(p, 3), n_i32(p, 4));
  i64 c   = n_add(p, n_i32(p, 5), n_i32(p, 6));
  i64 d   = n_i32(p, 7);
  i64 a_b = n_add(p, a, b);
  i64 c_d = n_add(p, c, d);

  N_RET(
    p,
    0, 0,
    n_add(p, a_b, c_d)
  );
)

ADD_TEST_(math_add_4b, 5+6+7+8,
  i64 p = p_new_entry(u);

  i64 a   = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b   = n_add(p, n_i32(p, 3), n_i32(p, 4));
  i64 c   = n_add(p, n_i32(p, 5), n_i32(p, 6));
  i64 d   = n_add(p, n_i32(p, 7), n_i32(p, 8));
  i64 a_b = n_add(p, a, b);
  i64 c_d = n_add(p, c, d);
  (void) a_b;

  N_RET(
    p,
    0, 0,
    c_d
  );
)

ADD_TEST_(math_add_8, 1+2+3+4+5+6+7+8,
  i64 p = p_new_entry(u);

  i64 a   = n_add(p, n_i32(p, 1), n_i32(p, 2));
  i64 b   = n_add(p, n_i32(p, 3), n_i32(p, 4));
  i64 c   = n_add(p, n_i32(p, 5), n_i32(p, 6));
  i64 d   = n_add(p, n_i32(p, 7), n_i32(p, 8));
  i64 a_b = n_add(p, a, b);
  i64 c_d = n_add(p, c, d);

  N_RET(
    p,
    0, 0,
    n_add(p, a_b, c_d)
  );
)

ADD_TEST_(math_sub_3, 3-2-1,
  i64 p = p_new_entry(u);

  i64 a = n_sub(p, n_i32(p, 3), n_i32(p, 2));
  i64 b = n_i32(p, 1);

  N_RET(
    p,
    0, 0,
    n_sub(p, a, b)
  );
)

ADD_TEST_(math_sub_4, (4-3)-(2-1),
  i64 p = p_new_entry(u);

  i64 a = n_sub(p, n_i32(p, 4), n_i32(p, 3));
  i64 b = n_sub(p, n_i32(p, 2), n_i32(p, 1));

  N_RET(
    p,
    0, 0,
    n_sub(p, a, b)
  );
)

ADD_TEST_(math_sub_5, ((5-3)-(1-4))-2,
  i64 p = p_new_entry(u);

  i64 a   = n_sub(p, n_i32(p, 5), n_i32(p, 3));
  i64 b   = n_sub(p, n_i32(p, 1), n_i32(p, 4));
  i64 c   = n_i32(p, 2);
  i64 a_b = n_sub(p, a, b);

  N_RET(
    p,
    0, 0,
    n_sub(p, a_b, c)
  );
)

ADD_TEST_(math_sub_6, ((6-1)-(5-4))-(3-2),
  i64 p = p_new_entry(u);

  i64 a   = n_sub(p, n_i32(p, 6), n_i32(p, 1));
  i64 b   = n_sub(p, n_i32(p, 5), n_i32(p, 4));
  i64 c   = n_sub(p, n_i32(p, 3), n_i32(p, 2));
  i64 a_b = n_sub(p, a, b);

  N_RET(
    p,
    0, 0,
    n_sub(p, a_b, c)
  );
)

ADD_TEST_(math_sub_7, ((7-2)-(2-3))-((4-5)-1),
  i64 p = p_new_entry(u);

  i64 a   = n_sub(p, n_i32(p, 7), n_i32(p, 2));
  i64 b   = n_sub(p, n_i32(p, 2), n_i32(p, 3));
  i64 c   = n_sub(p, n_i32(p, 4), n_i32(p, 5));
  i64 d   = n_i32(p, 1);
  i64 a_b = n_sub(p, a, b);
  i64 c_d = n_sub(p, c, d);

  N_RET(
    p,
    0, 0,
    n_sub(p, a_b, c_d)
  );
)

ADD_TEST_(math_sub_8, ((8-1)-(2-3))-((4-5)-(7-6)),
  i64 p = p_new_entry(u);

  i64 a   = n_sub(p, n_i32(p, 8), n_i32(p, 1));
  i64 b   = n_sub(p, n_i32(p, 2), n_i32(p, 3));
  i64 c   = n_sub(p, n_i32(p, 4), n_i32(p, 5));
  i64 d   = n_sub(p, n_i32(p, 7), n_i32(p, 6));
  i64 a_b = n_sub(p, a, b);
  i64 c_d = n_sub(p, c, d);

  N_RET(
    p,
    0, 0,
    n_sub(p, a_b, c_d)
  );
)

ADD_TEST_(math_reg_reuse, (1+2+3+4+5+6+7+8+9+10),
  i64 p = p_new_entry(u);

  i64 a =             n_i32(p,  1);
  i64 b = n_add(p, a, n_i32(p,  2));
  i64 c = n_add(p, b, n_i32(p,  3));
  i64 d = n_add(p, c, n_i32(p,  4));
  i64 e = n_add(p, d, n_i32(p,  5));
  i64 f = n_add(p, e, n_i32(p,  6));
  i64 g = n_add(p, f, n_i32(p,  7));
  i64 h = n_add(p, g, n_i32(p,  8));
  i64 i = n_add(p, h, n_i32(p,  9));
  i64 j = n_add(p, i, n_i32(p, 10));

  N_RET(p, 0, 0, j);
)

ADD_TEST_(cond_1, 1,
  i64 p = p_new_entry(u);

  i64 a = n_i32(p, 1);
  i64 b = n_if(p, 0, 0, a);
  N_RET(p, b, 0, 1);
  N_RET(p, b, 1, 2);
)

ADD_TEST_(cond_2, 2,
  i64 p = p_new_entry(u);

  i64 a = n_i32(p, 0);
  i64 b = n_if(p, 0, 0, a);
  N_RET(p, b, 0, 1);
  N_RET(p, b, 1, 2);
)

#endif // HELPERS

i32 main(i32 argc, c8 **argv) {
  b8 is_ok         = 1;
  b8 print_version = 0;
  b8 print_help    = 0;

  for (i32 i = 1; i < argc; ++i) {
    if (argv[i][0] == '?' && argv[i][1] == '\0')
      print_help = 1;
    else if (argv[i][0] == '-') {
      if (argv[i][1] == '-') {
        i64 len = str_len(argv[i] + 2, argv[i] + 128);
        if (str_eq(len, argv[i] + 2, 7, "version"))
          print_version = 1;
        else if (str_eq(len, argv[i] + 2, 4, "help"))
          print_help = 1;
        else {
          LOG(ERROR, "Unknown argument %s", argv[i]);
          is_ok = 0;
        }
      } else {
        for (i32 j = 1; argv[i][j] != '\0'; ++j)
          switch (argv[i][j]) {
            case 'V': print_version = 1; break;
            case 'h': print_help = 1;    break;

            default: {
              LOG(ERROR, "Unknown option %c", argv[i][j]);
              is_ok = 0;
            }
          }
      }
    } else {
      LOG(ERROR, "Unknown argument %s", argv[i]);
      is_ok = 0;
    }
  }

  if (!is_ok)
    return -1;

  LOG(INFO, "bxgen " VERSION);

  if (print_help) {
    //  TODO
    LOG(ERROR, "Not implemented");
    return 0;
  }

  if (print_version)
    return 0;

  i32 num_tests  = 0;
  i32 num_passed = 0;

  #define RUN_TEST_(t)            \
    do {                          \
      ++num_tests;                \
      if (t()) {                  \
        ++num_passed;             \
        LOG(INFO,  #t " - OK");   \
      } else                      \
        LOG(ERROR, #t " - FAIL"); \
    } while (0)

  #if HELPERS
  // RUN_TEST_(link_with_libc);
  RUN_TEST_(math_two_plus_two);
  RUN_TEST_(math_sixty_nine);
  RUN_TEST_(math_add_3);
  RUN_TEST_(math_add_4a);
  RUN_TEST_(math_add_5);
  RUN_TEST_(math_add_6);
  RUN_TEST_(math_add_7);
  RUN_TEST_(math_add_4b);
  RUN_TEST_(math_add_8);
  RUN_TEST_(math_sub_3);
  RUN_TEST_(math_sub_4);
  RUN_TEST_(math_sub_5);
  RUN_TEST_(math_sub_6);
  RUN_TEST_(math_sub_7);
  RUN_TEST_(math_sub_8);
  RUN_TEST_(math_reg_reuse);
  #endif

  #undef RUN_TEST_

  LOG(INFO, "%d of %d tests passed.", num_passed, num_tests);

  return num_passed == num_tests ? 0 : -1;
}

#endif // TESTING

#endif // BXGEN_IMPL_GUARD_
#endif // BXGEN_HEADER