Module: MilkTea::CBackend::RuntimeHelpers

Included in:
MilkTea::CBackend
Defined in:
lib/milk_tea/core/c_backend/runtime_helpers.rb

Instance Method Summary collapse

Instance Method Details

#emit_async_memory_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 225

def emit_async_memory_helpers
  [
    "#define MT_ASYNC_HEADER_SIZE (sizeof(uint64_t) + sizeof(uintptr_t))",
    "#define MT_ASYNC_MAGIC UINT64_C(0x4D5441464D454D00)",
    "",
    "static void* mt_async_alloc(uintptr_t size) {",
    "#{INDENT}char* raw = (char*) calloc(1, (size_t)(MT_ASYNC_HEADER_SIZE + size));",
    "#{INDENT}if (raw == NULL) {",
    "#{INDENT * 2}abort();",
    "#{INDENT}}",
    "#{INDENT}*(uint64_t*)raw = MT_ASYNC_MAGIC;",
    "#{INDENT}*(uintptr_t*)(raw + sizeof(uint64_t)) = 1;",
    "#{INDENT}return raw + MT_ASYNC_HEADER_SIZE;",
    "}",
    "",
    "static void mt_async_retain(void* frame) {",
    "#{INDENT}char* raw = (char*)frame - MT_ASYNC_HEADER_SIZE;",
    "#{INDENT}if (*(uint64_t*)raw != MT_ASYNC_MAGIC) return;",
    "#{INDENT}uintptr_t* ref = (uintptr_t*)(raw + sizeof(uint64_t));",
    "#{INDENT}(*ref)++;",
    "}",
    "",
    "static void mt_async_free(void* frame) {",
    "#{INDENT}char* raw = (char*)frame - MT_ASYNC_HEADER_SIZE;",
    "#{INDENT}if (*(uint64_t*)raw != MT_ASYNC_MAGIC) return;",
    "#{INDENT}uintptr_t* ref = (uintptr_t*)(raw + sizeof(uint64_t));",
    "#{INDENT}if (--(*ref) == 0) {",
    "#{INDENT * 2}free(raw);",
    "#{INDENT}}",
    "}",
  ]
end

#emit_checked_array_index_helper(type) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 625

def emit_checked_array_index_helper(type)
  helper_name = checked_array_index_helper_name(type)
  params = [c_declaration(pointer_to(array_element_type(type)), 'array'), c_declaration(Types::Registry.primitive('ptr_uint'), 'index')].join(', ')
  [
    "static inline #{c_function_declaration(pointer_to(array_element_type(type)), helper_name, params)} {",
    "#{INDENT}if (index >= #{array_length(type)}) mt_fatal(\"array index out of bounds\");",
    "#{INDENT}return &array[index];",
    "}",
  ]
end

#emit_checked_span_index_helper(type) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 636

def emit_checked_span_index_helper(type)
  helper_name = checked_span_index_helper_name(type)
  params = [c_declaration(type, 'span'), c_declaration(Types::Registry.primitive('ptr_uint'), 'index')].join(', ')
  [
    "static inline #{c_function_declaration(pointer_to(type.element_type), helper_name, params)} {",
    "#{INDENT}if (index >= span.len) mt_fatal(\"span index out of bounds\");",
    "#{INDENT}return &span.data[index];",
    "}",
  ]
end

#emit_detach_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 338

def emit_detach_helpers
  [
    "typedef struct {",
    "#{INDENT}uv_thread_t thread;",
    "} mt_detach_handle;",
    "",
    "static void* mt_detach_run(void (*work)(void*), void* cap) {",
    "#{INDENT}mt_detach_handle* h = (mt_detach_handle*)malloc(sizeof(mt_detach_handle));",
    "#{INDENT}uv_thread_create(&h->thread, work, cap);",
    "#{INDENT}return h;",
    "}",
    "",
    "static void mt_detach_join(void* handle) {",
    "#{INDENT}if (!handle) return;",
    "#{INDENT}mt_detach_handle* h = (mt_detach_handle*)handle;",
    "#{INDENT}uv_thread_join(&h->thread);",
    "#{INDENT}free(h);",
    "}",
  ]
end

#emit_entrypoint_argv_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 444

def emit_entrypoint_argv_helpers
  lines = []

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_entry_argv_to_span_str]) }
    lines.concat([
      "static mt_span_str mt_entry_argv_to_span_str(int32_t argc, char** argv, mt_str** items_out) {",
      "#{INDENT}uintptr_t len = argc > 0 ? (uintptr_t)argc : 0;",
      "#{INDENT}mt_str* items = NULL;",
      "#{INDENT}uintptr_t index = 0;",
      "#{INDENT}if (len > 0) {",
      "#{INDENT * 2}items = (mt_str*)malloc(len * sizeof(mt_str));",
      "#{INDENT * 2}if (items == NULL) abort();",
      "#{INDENT}}",
      "#{INDENT}while (index < len) {",
      "#{INDENT * 2}char* value = argv[index];",
      "#{INDENT * 2}items[index] = (mt_str){ .data = value, .len = (uintptr_t)strlen(value) };",
      "#{INDENT * 2}index++;",
      "#{INDENT}}",
      "#{INDENT}*items_out = items;",
      "#{INDENT}return (mt_span_str){ .data = items, .len = len };",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_free_entry_argv_strs]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_free_entry_argv_strs(mt_str* items) {",
      "#{INDENT}free(items);",
      "}",
    ])
  end

  lines
end

#emit_fatal_helper ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 6

def emit_fatal_helper
  lines = []

  if uses_mt_fatal_helper?
    lines.concat([
      "static _Noreturn void mt_fatal(const char* message) {",
      "#{INDENT}fputs(message, stderr);",
      "#{INDENT}fputc('\\n', stderr);",
      "#{INDENT}abort();",
      "}",
    ])
  end

  if uses_mt_fatal_str_helper?
    lines << "" unless lines.empty?
    lines.concat([
      "static _Noreturn void mt_fatal_str(mt_str message) {",
      "#{INDENT}fwrite(message.data, 1, message.len, stderr);",
      "#{INDENT}fputc('\\n', stderr);",
      "#{INDENT}abort();",
      "}",
    ])
  end

  lines
end

#emit_field_equality_guards(lines, left, right, type, outer_c: nil, indent: 1) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 181

def emit_field_equality_guards(lines, left, right, type, outer_c: nil, indent: 1)
  pad = INDENT * indent
  case type
  when Types::StringView
    lines << "#{pad}if (!mt_str_equal(#{left}, #{right})) return false;"
  when Types::Variant
    if aggregate_field_creates_cycle?(type, outer_c)
      lines << "#{pad}if (#{left} != #{right}) return false;"
    else
      lines << "#{pad}if (!mt_variant_eq_#{named_type_c_name(type)}(#{left}, #{right})) return false;"
    end
  when Types::VariantArmPayload
    if aggregate_field_creates_cycle?(type.variant_type, outer_c)
      lines << "#{pad}if (#{left} != #{right}) return false;"
    else
      lines << "#{pad}if (!mt_struct_eq_#{named_type_c_name(type)}(#{left}, #{right})) return false;"
    end
  when Types::Struct
    if aggregate_field_creates_cycle?(type, outer_c)
      lines << "#{pad}if (#{left} != #{right}) return false;"
    else
      lines << "#{pad}if (!mt_struct_eq_#{named_type_c_name(type)}(#{left}, #{right})) return false;"
    end
  when Types::Nullable
    if c_backend_pointer_like_type?(type.base)
      lines << "#{pad}if (#{left} != #{right}) return false;"
    else
      lines << "#{pad}if (#{left}.has_value != #{right}.has_value) return false;"
      lines << "#{pad}if (#{left}.has_value) {"
      emit_field_equality_guards(lines, "#{left}.value", "#{right}.value", type.base, outer_c:, indent: indent + 1)
      lines << "#{pad}}"
    end
  else
    if array_type?(type)
      count = array_length(type)
      lines << "#{pad}for (uintptr_t index = 0; index < #{count}; index++) {"
      emit_field_equality_guards(lines, "#{left}[index]", "#{right}[index]", array_element_type(type), outer_c:, indent: indent + 1)
      lines << "#{pad}}"
    else
      lines << "#{pad}if (#{left} != #{right}) return false;"
    end
  end
end

#emit_foreign_temp_cstr_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 359

def emit_foreign_temp_cstr_helpers
  lines = []

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_foreign_str_to_cstr_temp]) }
    lines.concat([
      "static const char* mt_foreign_str_to_cstr_temp(mt_str value) {",
      "#{INDENT}char* data = (char*)malloc(value.len + 1);",
      "#{INDENT}uintptr_t index = 0;",
      "#{INDENT}if (data == NULL) mt_fatal(\"foreign str temporary allocation failed\");",
      "#{INDENT}while (index < value.len) {",
      "#{INDENT * 2}data[index] = value.data[index];",
      "#{INDENT * 2}index++;",
      "#{INDENT}}",
      "#{INDENT}data[value.len] = '\\0';",
      "#{INDENT}return data;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_free_foreign_cstr_temp]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_free_foreign_cstr_temp(const char* value) {",
      "#{INDENT}free((void*)value);",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_foreign_strs_to_cstrs_temp]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_foreign_strs_to_cstrs_temp(mt_span_str values, char*** items_out, char** data_out, uintptr_t* len_out) {",
      "#{INDENT}uintptr_t total_bytes = 0;",
      "#{INDENT}uintptr_t index = 0;",
      "#{INDENT}uintptr_t offset = 0;",
      "#{INDENT}char** items = NULL;",
      "#{INDENT}char* data = NULL;",
      "#{INDENT}while (index < values.len) {",
      "#{INDENT * 2}total_bytes += values.data[index].len + 1;",
      "#{INDENT * 2}index++;",
      "#{INDENT}}",
      "#{INDENT}if (values.len > 0) {",
      "#{INDENT * 2}items = (char**)malloc(values.len * sizeof(char*));",
      "#{INDENT * 2}if (items == NULL) mt_fatal(\"foreign string-list temporary allocation failed\");",
      "#{INDENT}}",
      "#{INDENT}if (total_bytes > 0) {",
      "#{INDENT * 2}data = (char*)malloc(total_bytes);",
      "#{INDENT * 2}if (data == NULL) {",
      "#{INDENT * 3}free(items);",
      "#{INDENT * 3}mt_fatal(\"foreign string-list temporary allocation failed\");",
      "#{INDENT * 2}}",
      "#{INDENT}}",
      "#{INDENT}index = 0;",
      "#{INDENT}while (index < values.len) {",
      "#{INDENT * 2}mt_str value = values.data[index];",
      "#{INDENT * 2}uintptr_t byte_index = 0;",
      "#{INDENT * 2}items[index] = data + offset;",
      "#{INDENT * 2}while (byte_index < value.len) {",
      "#{INDENT * 3}data[offset + byte_index] = value.data[byte_index];",
      "#{INDENT * 3}byte_index++;",
      "#{INDENT * 2}}",
      "#{INDENT * 2}data[offset + value.len] = '\\0';",
      "#{INDENT * 2}offset += value.len + 1;",
      "#{INDENT * 2}index++;",
      "#{INDENT}}",
      "#{INDENT}*items_out = items;",
      "#{INDENT}*data_out = data;",
      "#{INDENT}*len_out = values.len;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_free_foreign_cstrs_temp]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_free_foreign_cstrs_temp(char** items, char* data) {",
      "#{INDENT}free(items);",
      "#{INDENT}free(data);",
      "}",
    ])
  end

  lines
end

#emit_nullable_array_index_helper(type) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 647

def emit_nullable_array_index_helper(type)
  helper_name = nullable_array_index_helper_name(type)
  params = [c_declaration(pointer_to(array_element_type(type)), 'array'), c_declaration(Types::Registry.primitive('ptr_uint'), 'index')].join(', ')
  [
    "static inline #{c_function_declaration(pointer_to(array_element_type(type)), helper_name, params)} {",
    "#{INDENT}if (index >= #{array_length(type)}) return NULL;",
    "#{INDENT}return &array[index];",
    "}",
  ]
end

#emit_nullable_span_index_helper(type) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 658

def emit_nullable_span_index_helper(type)
  helper_name = nullable_span_index_helper_name(type)
  params = [c_declaration(type, 'span'), c_declaration(Types::Registry.primitive('ptr_uint'), 'index')].join(', ')
  [
    "static inline #{c_function_declaration(pointer_to(type.element_type), helper_name, params)} {",
    "#{INDENT}if (index >= span.len) return NULL;",
    "#{INDENT}return &span.data[index];",
    "}",
  ]
end

#emit_parallel_for_helper ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 258

def emit_parallel_for_helper
  [
    "typedef struct {",
    "#{INDENT}void (*work)(void* data, int64_t start, int64_t end);",
    "#{INDENT}void* data;",
    "#{INDENT}int64_t start;",
    "#{INDENT}int64_t end;",
    "} mt_pfor_chunk;",
    "",
    "static void mt_pfor_runner(void* arg) {",
    "#{INDENT}mt_pfor_chunk* chunk = (mt_pfor_chunk*)arg;",
    "#{INDENT}chunk->work(chunk->data, chunk->start, chunk->end);",
    "}",
    "",
    "static void mt_parallel_for(void (*work)(void* data, int64_t start, int64_t end), void* data, int64_t count) {",
    "#{INDENT}if (count <= 0) return;",
    "#{INDENT}uv_cpu_info_t* cpu_info;",
    "#{INDENT}int ncpu = 1;",
    "#{INDENT}if (uv_cpu_info(&cpu_info, &ncpu) == 0) {",
    "#{INDENT * 2}uv_free_cpu_info(cpu_info, ncpu);",
    "#{INDENT}}",
    "#{INDENT}if (ncpu < 1) ncpu = 1;",
    "#{INDENT}if (ncpu > 64) ncpu = 64;",
    "#{INDENT}if (count < (int64_t)ncpu) ncpu = (int)count;",
    "#{INDENT}int64_t chunk_size = (count + ncpu - 1) / ncpu;",
    "#{INDENT}mt_pfor_chunk chunks[64];",
    "#{INDENT}uv_thread_t threads[64];",
    "#{INDENT}int nworkers = 0;",
    "#{INDENT}for (int t = 1; t < ncpu; t++) {",
    "#{INDENT * 2}int64_t s = t * chunk_size;",
    "#{INDENT * 2}int64_t e = s + chunk_size;",
    "#{INDENT * 2}if (e > count) e = count;",
    "#{INDENT * 2}if (s >= count) break;",
    "#{INDENT * 2}chunks[nworkers].work = work;",
    "#{INDENT * 2}chunks[nworkers].data = data;",
    "#{INDENT * 2}chunks[nworkers].start = s;",
    "#{INDENT * 2}chunks[nworkers].end = e;",
    "#{INDENT * 2}uv_thread_create(&threads[nworkers], mt_pfor_runner, &chunks[nworkers]);",
    "#{INDENT * 2}nworkers++;",
    "#{INDENT}}",
    "#{INDENT}int64_t first_end = chunk_size < count ? chunk_size : count;",
    "#{INDENT}work(data, 0, first_end);",
    "#{INDENT}for (int t = 0; t < nworkers; t++) {",
    "#{INDENT * 2}uv_thread_join(&threads[t]);",
    "#{INDENT}}",
    "}",
  ]
end

#emit_span_slice_helper(helper_name) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 87

def emit_span_slice_helper(helper_name)
  span_name = helper_name.sub("mt_span_slice_", "mt_span_")
  [
    "static inline #{span_name} #{helper_name}(#{span_name} span, uintptr_t start, uintptr_t stop) {",
    "#{INDENT}if (start > stop || stop > span.len) mt_fatal(\"span slice out of bounds\");",
    "#{INDENT}return (#{span_name}){ .data = span.data + start, .len = stop - start };",
    "}",
  ]
end

#emit_spawn_all_helper ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 307

def emit_spawn_all_helper
  [
    "typedef struct {",
    "#{INDENT}void (*work)(void* data);",
    "#{INDENT}void* data;",
    "} mt_spawn_item;",
    "",
    "static void mt_spawn_item_runner(void* arg) {",
    "#{INDENT}mt_spawn_item* item = (mt_spawn_item*)arg;",
    "#{INDENT}item->work(item->data);",
    "}",
    "",
    "static void mt_spawn_all(mt_spawn_item* items, int count) {",
    "#{INDENT}if (count <= 0) return;",
    "#{INDENT}uv_thread_t threads[64];",
    "#{INDENT}int nworkers = 0;",
    "#{INDENT}for (int t = 1; t < count && nworkers < 63; t++) {",
    "#{INDENT * 2}uv_thread_create(&threads[nworkers], mt_spawn_item_runner, &items[t]);",
    "#{INDENT * 2}nworkers++;",
    "#{INDENT}}",
    "#{INDENT}items[0].work(items[0].data);",
    "#{INDENT}for (int t = 0; t < nworkers; t++) {",
    "#{INDENT * 2}uv_thread_join(&threads[t]);",
    "#{INDENT}}",
    "#{INDENT}for (int t = nworkers + 1; t < count; t++) {",
    "#{INDENT * 2}items[t].work(items[t].data);",
    "#{INDENT}}",
    "}",
  ]
end

#emit_str_buffer_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 540

def emit_str_buffer_helpers
  lines = []

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_len mt_str_buffer_as_cstr mt_str_buffer_append]) }
    lines.concat([
      "static uintptr_t mt_str_buffer_len(char* data, uintptr_t cap, uintptr_t* len, bool* dirty) {",
      "#{INDENT}if (*dirty) {",
      "#{INDENT * 2}uintptr_t current = 0;",
      "#{INDENT * 2}while (current < cap + 1 && data[current] != '\\0') {",
      "#{INDENT * 3}current++;",
      "#{INDENT * 2}}",
      "#{INDENT * 2}if (current > cap) mt_fatal(\"str_buffer text requires a trailing NUL within capacity\");",
      "#{INDENT * 2}if (!mt_is_valid_utf8(data, current)) mt_fatal(\"str_buffer text must be valid UTF-8\");",
      "#{INDENT * 2}*len = current;",
      "#{INDENT * 2}*dirty = false;",
      "#{INDENT}}",
      "#{INDENT}return *len;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_as_cstr]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static const char* mt_str_buffer_as_cstr(char* data, uintptr_t cap, uintptr_t* len, bool* dirty) {",
      "#{INDENT}(void)mt_str_buffer_len(data, cap, len, dirty);",
      "#{INDENT}return data;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_clear]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_str_buffer_clear(char* data, uintptr_t cap, uintptr_t* len, bool* dirty) {",
      "#{INDENT}memset(data, 0, cap + 1);",
      "#{INDENT}*len = 0;",
      "#{INDENT}*dirty = false;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_assign]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_str_buffer_assign(mt_str value, char* data, uintptr_t cap, uintptr_t* len, bool* dirty) {",
      "#{INDENT}if (value.len > cap) mt_fatal(\"str_buffer.assign exceeds capacity\");",
      "#{INDENT}memcpy(data, value.data, value.len);",
      "#{INDENT}data[value.len] = '\\0';",
      "#{INDENT}if (value.len < cap + 1) memset(data + value.len + 1, 0, cap - value.len);",
      "#{INDENT}*len = value.len;",
      "#{INDENT}*dirty = false;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_append]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static void mt_str_buffer_append(mt_str value, char* data, uintptr_t cap, uintptr_t* len, bool* dirty) {",
      "#{INDENT}uintptr_t current = mt_str_buffer_len(data, cap, len, dirty);",
      "#{INDENT}if (value.len > cap - current) mt_fatal(\"str_buffer.append exceeds capacity\");",
      "#{INDENT}memcpy(data + current, value.data, value.len);",
      "#{INDENT}current += value.len;",
      "#{INDENT}data[current] = '\\0';",
      "#{INDENT}*len = current;",
      "#{INDENT}*dirty = false;",
      "}",
    ])
  end

  if emitted_functions.any? { |function| function_uses_named_call?(function, %w[mt_str_buffer_prepare_write]) }
    lines << "" unless lines.empty?
    lines.concat([
      "static char* mt_str_buffer_prepare_write(char* data, uintptr_t cap, bool* dirty) {",
      "#{INDENT}data[cap] = '\\0';",
      "#{INDENT}*dirty = true;",
      "#{INDENT}return data;",
      "}",
    ])
  end

  lines
end

#emit_str_concat_helper ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 45

def emit_str_concat_helper
  [
    "#define MT_STR_CONCAT_BUF_SIZE 65536",
    "",
    "static _Thread_local char mt_str_concat_buf[MT_STR_CONCAT_BUF_SIZE];",
    "static _Thread_local uintptr_t mt_str_concat_offset = 0;",
    "",
    "static mt_str mt_str_concat(mt_str a, mt_str b) {",
    "#{INDENT}uintptr_t total = a.len + b.len;",
    "#{INDENT}if (total > MT_STR_CONCAT_BUF_SIZE) mt_fatal(\"str concatenation exceeds the scratch buffer budget\");",
    "#{INDENT}if (mt_str_concat_offset + total > MT_STR_CONCAT_BUF_SIZE) {",
    "#{INDENT * 2}mt_str_concat_offset = 0;",
    "#{INDENT}}",
    "#{INDENT}char* buf = mt_str_concat_buf + mt_str_concat_offset;",
    "#{INDENT}if (a.len > 0) memcpy(buf, a.data, a.len);",
    "#{INDENT}if (b.len > 0) memcpy(buf + a.len, b.data, b.len);",
    "#{INDENT}mt_str_concat_offset += total;",
    "#{INDENT}return (mt_str){ .data = buf, .len = total };",
    "}",
  ]
end

#emit_str_equality_helper ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 33

def emit_str_equality_helper
  [
    "static bool mt_str_equal(mt_str left, mt_str right) {",
    "#{INDENT}if (left.len != right.len) return false;",
    "#{INDENT}for (uintptr_t index = 0; index < left.len; index++) {",
    "#{INDENT * 2}if (left.data[index] != right.data[index]) return false;",
    "#{INDENT}}",
    "#{INDENT}return true;",
    "}",
  ]
end

#emit_str_literal_constants(literals) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 669

def emit_str_literal_constants(literals)
  literals.each_with_index.map do |value, i|
    "static const mt_str #{str_literal_name(i)} = { .data = #{value.inspect}, .len = #{value.bytesize} };"
  end
end

#emit_str_slice_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 67

def emit_str_slice_helpers
  [
    "static uint8_t mt_str_index(mt_str text, uintptr_t index) {",
    "#{INDENT}if (index >= text.len) mt_fatal(\"str index out of bounds\");",
    "#{INDENT}return (uint8_t)text.data[index];",
    "}",
    "",
    "static bool mt_str_utf8_boundary(mt_str text, uintptr_t index) {",
    "#{INDENT}if (index == 0 || index == text.len) return true;",
    "#{INDENT}return ((uint8_t)text.data[index] & 0xC0) != 0x80;",
    "}",
    "",
    "static mt_str mt_str_slice(mt_str text, uintptr_t start, uintptr_t stop) {",
    "#{INDENT}if (start > stop || stop > text.len) mt_fatal(\"str slice out of bounds\");",
    "#{INDENT}if (!mt_str_utf8_boundary(text, start) || !mt_str_utf8_boundary(text, stop)) mt_fatal(\"str slice bounds must be UTF-8 code-unit boundaries\");",
    "#{INDENT}return (mt_str){ .data = text.data + start, .len = stop - start };",
    "}",
  ]
end

#emit_struct_equality_helper(struct_decl_or_type) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 152

def emit_struct_equality_helper(struct_decl_or_type)
  if struct_decl_or_type.is_a?(IR::StructDecl)
    outer_c = struct_decl_or_type.linkage_name
    fields = struct_decl_or_type.fields
  elsif struct_decl_or_type.is_a?(Types::VariantArmPayload)
    payload = struct_decl_or_type
    outer_c = named_type_c_name(payload)
    arm_fields = payload.variant_type.arm(payload.arm_name) || {}
    fields = arm_fields.map { |name, field_type| IR::Field.new(name:, type: field_type) }
  else
    outer_c = named_type_c_name(struct_decl_or_type)
    fields = struct_decl_or_type.fields.map { |name, field_type| IR::Field.new(name:, type: field_type) }
  end

  lines = ["static bool mt_struct_eq_#{outer_c}(struct #{outer_c} left, struct #{outer_c} right) {"]
  fields.each do |field|
    emit_field_equality_guards(
      lines,
      "left.#{sanitize_c_identifier(field.name)}",
      "right.#{sanitize_c_identifier(field.name)}",
      field.type,
      outer_c:,
    )
  end
  lines << "#{INDENT}return true;"
  lines << "}"
  lines
end

#emit_struct_equality_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 135

def emit_struct_equality_helpers
  struct_decls_by_linkage = (emitted_aggregate_structs + collect_generic_struct_decls).each_with_object({}) { |decl, map| map[decl.linkage_name] = decl }
  struct_equality_types
    .filter_map do |type|
      if type.is_a?(Types::VariantArmPayload)
        type
      elsif struct_decls_by_linkage.key?(named_type_c_name(type))
        struct_decls_by_linkage[named_type_c_name(type)]
      elsif type.is_a?(Types::Struct)
        # External structs (raw ABI bindings) are not lowered into
        # @program.structs, but their field layout is still known.
        type
      end
    end
    .flat_map { |decl_or_type| emit_struct_equality_helper(decl_or_type) }
end

#emit_utf8_validation_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 480

def emit_utf8_validation_helpers
  [
    "static bool mt_is_utf8_continuation_byte(unsigned char byte) {",
    "#{INDENT}return (byte & 0xC0u) == 0x80u;",
    "}",
    "",
    "static bool mt_is_valid_utf8(const char* data, uintptr_t len) {",
    "#{INDENT}uintptr_t index = 0;",
    "#{INDENT}while (index < len) {",
    "#{INDENT * 2}unsigned char lead = (unsigned char) data[index];",
    "#{INDENT * 2}if (lead < 0x80u) {",
    "#{INDENT * 3}index++;",
    "#{INDENT * 3}continue;",
    "#{INDENT * 2}}",
    "#{INDENT * 2}if (lead < 0xC2u) return false;",
    "#{INDENT * 2}if (lead < 0xE0u) {",
    "#{INDENT * 3}if (index + 1 >= len) return false;",
    "#{INDENT * 3}unsigned char byte1 = (unsigned char) data[index + 1];",
    "#{INDENT * 3}if (!mt_is_utf8_continuation_byte(byte1)) return false;",
    "#{INDENT * 3}index += 2;",
    "#{INDENT * 3}continue;",
    "#{INDENT * 2}}",
    "#{INDENT * 2}if (lead < 0xF0u) {",
    "#{INDENT * 3}if (index + 2 >= len) return false;",
    "#{INDENT * 3}unsigned char byte1 = (unsigned char) data[index + 1];",
    "#{INDENT * 3}unsigned char byte2 = (unsigned char) data[index + 2];",
    "#{INDENT * 3}if (lead == 0xE0u) {",
    "#{INDENT * 4}if (byte1 < 0xA0u || byte1 > 0xBFu) return false;",
    "#{INDENT * 3}} else if (lead == 0xEDu) {",
    "#{INDENT * 4}if (byte1 < 0x80u || byte1 > 0x9Fu) return false;",
    "#{INDENT * 3}} else if (!mt_is_utf8_continuation_byte(byte1)) {",
    "#{INDENT * 4}return false;",
    "#{INDENT * 3}}",
    "#{INDENT * 3}if (!mt_is_utf8_continuation_byte(byte2)) return false;",
    "#{INDENT * 3}index += 3;",
    "#{INDENT * 3}continue;",
    "#{INDENT * 2}}",
    "#{INDENT * 2}if (lead < 0xF5u) {",
    "#{INDENT * 3}if (index + 3 >= len) return false;",
    "#{INDENT * 3}unsigned char byte1 = (unsigned char) data[index + 1];",
    "#{INDENT * 3}unsigned char byte2 = (unsigned char) data[index + 2];",
    "#{INDENT * 3}unsigned char byte3 = (unsigned char) data[index + 3];",
    "#{INDENT * 3}if (lead == 0xF0u) {",
    "#{INDENT * 4}if (byte1 < 0x90u || byte1 > 0xBFu) return false;",
    "#{INDENT * 3}} else if (lead == 0xF4u) {",
    "#{INDENT * 4}if (byte1 < 0x80u || byte1 > 0x8Fu) return false;",
    "#{INDENT * 3}} else if (!mt_is_utf8_continuation_byte(byte1)) {",
    "#{INDENT * 4}return false;",
    "#{INDENT * 3}}",
    "#{INDENT * 3}if (!mt_is_utf8_continuation_byte(byte2) || !mt_is_utf8_continuation_byte(byte3)) return false;",
    "#{INDENT * 3}index += 4;",
    "#{INDENT * 3}continue;",
    "#{INDENT * 2}}",
    "#{INDENT * 2}return false;",
    "#{INDENT}}",
    "#{INDENT}return true;",
    "}",
  ]
end

#emit_variant_equality_helper(variant_decl) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 104

def emit_variant_equality_helper(variant_decl)
  outer_c = variant_decl.linkage_name
  lines = ["static bool mt_variant_eq_#{outer_c}(struct #{outer_c} left, struct #{outer_c} right) {"]
  lines << "#{INDENT}if (left.kind != right.kind) return false;"
  lines << "#{INDENT}switch (left.kind) {"

  variant_decl.arms.each do |arm|
    lines << "#{INDENT * 2}case #{outer_c}_kind_#{arm.name}:"
    if arm.fields.empty?
      lines << "#{INDENT * 3}return true;"
    else
      arm.fields.each do |field|
        emit_field_equality_guards(
          lines,
          "left.data.#{sanitize_c_identifier(arm.name)}.#{sanitize_c_identifier(field.name)}",
          "right.data.#{sanitize_c_identifier(arm.name)}.#{sanitize_c_identifier(field.name)}",
          field.type,
          outer_c:,
          indent: 3,
        )
      end
      lines << "#{INDENT * 3}return true;"
    end
  end

  lines << "#{INDENT * 2}default: return true;"
  lines << "#{INDENT}}"
  lines << "}"
  lines
end

#emit_variant_equality_helpers ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 97

def emit_variant_equality_helpers
  variant_decls_by_linkage = (emitted_aggregate_variants + collect_generic_variant_decls).each_with_object({}) { |decl, map| map[decl.linkage_name] = decl }
  variant_equality_types
    .filter_map { |type| variant_decls_by_linkage[named_type_c_name(type)] }
    .flat_map { |variant_decl| emit_variant_equality_helper(variant_decl) }
end

#str_literal_name(index) ⇒ Object 



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# File 'lib/milk_tea/core/c_backend/runtime_helpers.rb', line 675

def str_literal_name(index)
  "mt_str_lit_#{index}"
end