protobuf/upb/port/def.inc

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

/*
 * This is where we define internal portability macros used across upb.
 *
 * All of these macros are undef'd in undef.inc to avoid leaking them to users.
 *
 * The correct usage is:
 *
 *   #include "upb/foobar.h"
 *   #include "upb/baz.h"
 *
 *   // MUST be last included header.
 *   #include "upb/port/def.inc"
 *
 *   // Code for this file.
 *   // <...>
 *
 *   // Can be omitted for .c files, required for .h.
 *   #include "upb/port/undef.inc"
 *
 * This file is private and must not be included by users!
 */

#if !((defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
      (defined(__cplusplus) && __cplusplus >= 201402L) ||           \
      (defined(_MSC_VER) && _MSC_VER >= 1900))
#error upb requires C99 or C++14 or MSVC >= 2015.
#endif

// Portable check for GCC minimum version:
// https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
#define UPB_GNUC_MIN(x, y) \
  (__GNUC__ > (x) || __GNUC__ == (x) && __GNUC_MINOR__ >= (y))
#else
#define UPB_GNUC_MIN(x, y) 0
#endif

#include <assert.h>
#include <setjmp.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>

#ifndef UINTPTR_MAX
Error, UINTPTR_MAX is undefined
#endif

#if UINTPTR_MAX == 0xffffffff
#define UPB_SIZE(size32, size64) size32
#else
#define UPB_SIZE(size32, size64) size64
#endif

/* If we always read/write as a consistent type to each address, this shouldn't
 * violate aliasing.
 */
#define UPB_PTR_AT(msg, ofs, type) ((type*)((char*)(msg) + (ofs)))

#define UPB_MAPTYPE_STRING 0

// UPB_EXPORT: always generate a public symbol.
#if defined(__GNUC__) || defined(__clang__)
#define UPB_EXPORT __attribute__((visibility("default"))) __attribute__((used))
#else
#define UPB_EXPORT
#endif

// UPB_INLINE: inline if possible, emit standalone code if required.
#ifdef __cplusplus
#define UPB_INLINE inline
#elif defined (__GNUC__) || defined(__clang__)
#define UPB_INLINE static __inline__
#else
#define UPB_INLINE static
#endif

#ifdef UPB_BUILD_API
#define UPB_API UPB_EXPORT
#define UPB_API_INLINE UPB_EXPORT
#else
#define UPB_API
#define UPB_API_INLINE UPB_INLINE
#endif

#define UPB_MALLOC_ALIGN 8
#define UPB_ALIGN_UP(size, align) (((size) + (align) - 1) / (align) * (align))
#define UPB_ALIGN_DOWN(size, align) ((size) / (align) * (align))
#define UPB_ALIGN_MALLOC(size) UPB_ALIGN_UP(size, UPB_MALLOC_ALIGN)
#ifdef __clang__
#define UPB_ALIGN_OF(type) _Alignof(type)
#else
#define UPB_ALIGN_OF(type) offsetof (struct { char c; type member; }, member)
#endif

#ifdef _MSC_VER
// Some versions of our Windows compiler don't support the C11 syntax.
#define UPB_ALIGN_AS(x) __declspec(align(x))
#else
#define UPB_ALIGN_AS(x) _Alignas(x)
#endif

// Hints to the compiler about likely/unlikely branches.
#if defined (__GNUC__) || defined(__clang__)
#define UPB_LIKELY(x) __builtin_expect((bool)(x), 1)
#define UPB_UNLIKELY(x) __builtin_expect((bool)(x), 0)
#else
#define UPB_LIKELY(x) (x)
#define UPB_UNLIKELY(x) (x)
#endif

// Macros for function attributes on compilers that support them.
#ifdef __GNUC__
#define UPB_FORCEINLINE __inline__ __attribute__((always_inline)) static
#define UPB_NOINLINE __attribute__((noinline))
#define UPB_NORETURN __attribute__((__noreturn__))
#define UPB_PRINTF(str, first_vararg) __attribute__((format (printf, str, first_vararg)))
#elif defined(_MSC_VER)
#define UPB_NOINLINE
#define UPB_FORCEINLINE static
#define UPB_NORETURN __declspec(noreturn)
#define UPB_PRINTF(str, first_vararg)
#else  /* !defined(__GNUC__) */
#define UPB_FORCEINLINE static
#define UPB_NOINLINE
#define UPB_NORETURN
#define UPB_PRINTF(str, first_vararg)
#endif

#define UPB_MAX(x, y) ((x) > (y) ? (x) : (y))
#define UPB_MIN(x, y) ((x) < (y) ? (x) : (y))

#define UPB_UNUSED(var) (void)var

// UPB_ASSUME(): in release mode, we tell the compiler to assume this is true.
#ifdef NDEBUG
#ifdef __GNUC__
#define UPB_ASSUME(expr) if (!(expr)) __builtin_unreachable()
#elif defined _MSC_VER
#define UPB_ASSUME(expr) if (!(expr)) __assume(0)
#else
#define UPB_ASSUME(expr) do {} while (false && (expr))
#endif
#else
#define UPB_ASSUME(expr) assert(expr)
#endif

/* UPB_ASSERT(): in release mode, we use the expression without letting it be
 * evaluated.  This prevents "unused variable" warnings. */
#ifdef NDEBUG
#define UPB_ASSERT(expr) do {} while (false && (expr))
#else
#define UPB_ASSERT(expr) assert(expr)
#endif

#if defined(__GNUC__) || defined(__clang__)
#define UPB_UNREACHABLE() do { assert(0); __builtin_unreachable(); } while(0)
#elif defined(_MSC_VER)
#define UPB_UNREACHABLE() \
  do {                    \
    assert(0);            \
    __assume(0);          \
  } while (0)
#else
#define UPB_UNREACHABLE() do { assert(0); } while(0)
#endif

/* UPB_SETJMP() / UPB_LONGJMP(): avoid setting/restoring signal mask. */
#ifdef __APPLE__
#define UPB_SETJMP(buf) _setjmp(buf)
#define UPB_LONGJMP(buf, val) _longjmp(buf, val)
#else
#define UPB_SETJMP(buf) setjmp(buf)
#define UPB_LONGJMP(buf, val) longjmp(buf, val)
#endif

#ifdef __GNUC__
#define UPB_USE_C11_ATOMICS
#define UPB_ATOMIC(T) _Atomic(T)
#else
#define UPB_ATOMIC(T) T
#endif

/* UPB_PTRADD(ptr, ofs): add pointer while avoiding "NULL + 0" UB */
#define UPB_PTRADD(ptr, ofs) ((ofs) ? (ptr) + (ofs) : (ptr))

#define UPB_PRIVATE(x) x##_dont_copy_me__upb_internal_use_only

#ifdef UPB_ALLOW_PRIVATE_ACCESS__FOR_BITS_ONLY
#define UPB_ONLYBITS(x) x
#else
#define UPB_ONLYBITS(x) UPB_PRIVATE(x)
#endif

/* Configure whether fasttable is switched on or not. *************************/

#ifdef __has_attribute
#define UPB_HAS_ATTRIBUTE(x) __has_attribute(x)
#else
#define UPB_HAS_ATTRIBUTE(x) 0
#endif

#if UPB_HAS_ATTRIBUTE(musttail)
#define UPB_MUSTTAIL __attribute__((musttail))
#else
#define UPB_MUSTTAIL
#endif

#undef UPB_HAS_ATTRIBUTE

/* This check is not fully robust: it does not require that we have "musttail"
 * support available. We need tail calls to avoid consuming arbitrary amounts
 * of stack space.
 *
 * GCC/Clang can mostly be trusted to generate tail calls as long as
 * optimization is enabled, but, debug builds will not generate tail calls
 * unless "musttail" is available.
 *
 * We should probably either:
 *   1. require that the compiler supports musttail.
 *   2. add some fallback code for when musttail isn't available (ie. return
 *      instead of tail calling). This is safe and portable, but this comes at
 *      a CPU cost.
 */
#if (defined(__x86_64__) || defined(__aarch64__)) && defined(__GNUC__)
#define UPB_FASTTABLE_SUPPORTED 1
#else
#define UPB_FASTTABLE_SUPPORTED 0
#endif

/* define UPB_ENABLE_FASTTABLE to force fast table support.
 * This is useful when we want to ensure we are really getting fasttable,
 * for example for testing or benchmarking. */
#if defined(UPB_ENABLE_FASTTABLE)
#if !UPB_FASTTABLE_SUPPORTED
#error fasttable is x86-64/ARM64 only and requires GCC or Clang.
#endif
#define UPB_FASTTABLE 1
/* Define UPB_TRY_ENABLE_FASTTABLE to use fasttable if possible.
 * This is useful for releasing code that might be used on multiple platforms,
 * for example the PHP or Ruby C extensions. */
#elif defined(UPB_TRY_ENABLE_FASTTABLE)
#define UPB_FASTTABLE UPB_FASTTABLE_SUPPORTED
#else
#define UPB_FASTTABLE 0
#endif

/* UPB_FASTTABLE_INIT() allows protos compiled for fasttable to gracefully
 * degrade to non-fasttable if the runtime or platform do not support it. */
#if !UPB_FASTTABLE
#define UPB_FASTTABLE_INIT(...)
#define UPB_FASTTABLE_MASK(mask) -1
#else
#define UPB_FASTTABLE_INIT(...) __VA_ARGS__
#define UPB_FASTTABLE_MASK(mask) mask
#endif

#undef UPB_FASTTABLE_SUPPORTED

/* ASAN poisoning (for arena).
 * If using UPB from an interpreted language like Ruby, a build of the
 * interpreter compiled with ASAN enabled must be used in order to get sane and
 * expected behavior.
 */

/* Due to preprocessor limitations, the conditional logic for setting
 * UPN_CLANG_ASAN below cannot be consolidated into a portable one-liner.
 * See https://gcc.gnu.org/onlinedocs/cpp/_005f_005fhas_005fattribute.html.
 */
#if defined(__has_feature)
#if __has_feature(address_sanitizer)
#define UPB_CLANG_ASAN 1
#else
#define UPB_CLANG_ASAN 0
#endif
#else
#define UPB_CLANG_ASAN 0
#endif

#if defined(__SANITIZE_ADDRESS__) || UPB_CLANG_ASAN
#define UPB_ASAN 1
#define UPB_ASAN_GUARD_SIZE 32
#ifdef __cplusplus
    extern "C" {
#endif
void __asan_poison_memory_region(void const volatile *addr, size_t size);
void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
#ifdef __cplusplus
}  /* extern "C" */
#endif
#define UPB_POISON_MEMORY_REGION(addr, size) \
  __asan_poison_memory_region((addr), (size))
#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
  __asan_unpoison_memory_region((addr), (size))
#else
#define UPB_ASAN 0
#define UPB_ASAN_GUARD_SIZE 0
#define UPB_POISON_MEMORY_REGION(addr, size) \
  ((void)(addr), (void)(size))
#define UPB_UNPOISON_MEMORY_REGION(addr, size) \
  ((void)(addr), (void)(size))
#endif

/* Disable proto2 arena behavior (TEMPORARY) **********************************/

#ifdef UPB_DISABLE_CLOSED_ENUM_CHECKING
#define UPB_TREAT_CLOSED_ENUMS_LIKE_OPEN 1
#else
#define UPB_TREAT_CLOSED_ENUMS_LIKE_OPEN 0
#endif

#if defined(__cplusplus)
#if defined(__clang__) || UPB_GNUC_MIN(6, 0)
// https://gcc.gnu.org/gcc-6/changes.html
#if __cplusplus >= 201402L
#define UPB_DEPRECATED [[deprecated]]
#else
#define UPB_DEPRECATED __attribute__((deprecated))
#endif
#else
#define UPB_DEPRECATED
#endif
#else
#define UPB_DEPRECATED
#endif

// begin:google_only
// #define UPB_IS_GOOGLE3
// end:google_only

#if defined(UPB_IS_GOOGLE3) && !defined(UPB_BOOTSTRAP_STAGE0)
#define UPB_DESC(sym) proto2_##sym
#define UPB_DESC_MINITABLE(sym) &proto2__##sym##_msg_init
#elif defined(UPB_BOOTSTRAP_STAGE0)
#define UPB_DESC(sym) google_protobuf_##sym
#define UPB_DESC_MINITABLE(sym) google__protobuf__##sym##_msg_init()
#else
#define UPB_DESC(sym) google_protobuf_##sym
#define UPB_DESC_MINITABLE(sym) &google__protobuf__##sym##_msg_init
#endif


// Linker arrays combine elements from multiple translation units into a single
// array that can be iterated over at runtime.
//
// It is an alternative to pre-main "registration" functions.
//
// Usage:
//
//   // In N translation units.
//   UPB_LINKARR_APPEND(foo_array) static int elems[3] = {1, 2, 3};
//
//   // At runtime:
//   UPB_LINKARR_DECLARE(foo_array, int);
//
//   void f() {
//     const int* start = UPB_LINKARR_START(foo_array);
//     const int* stop = UPB_LINKARR_STOP(foo_array);
//     for (const int* p = start; p < stop; p++) {
//       // Windows can introduce zero padding, so we have to skip zeroes.
//       if (*p != 0) {
//         vec.push_back(*p);
//       }
//     }
//   }

#if defined(__ELF__) || defined(__wasm__)

#define UPB_LINKARR_APPEND(name) \
  __attribute__((retain, used, section("linkarr_" #name)))
#define UPB_LINKARR_DECLARE(name, type)     \
  extern type const __start_linkarr_##name; \
  extern type const __stop_linkarr_##name;  \
  UPB_LINKARR_APPEND(name) type UPB_linkarr_internal_empty_##name[1]
#define UPB_LINKARR_START(name) (&__start_linkarr_##name)
#define UPB_LINKARR_STOP(name) (&__stop_linkarr_##name)

#elif defined(__MACH__)

/* As described in: https://stackoverflow.com/a/22366882 */
#define UPB_LINKARR_APPEND(name) \
  __attribute__((retain, used, section("__DATA,__la_" #name)))
#define UPB_LINKARR_DECLARE(name, type)           \
  extern type const __start_linkarr_##name __asm( \
      "section$start$__DATA$__la_" #name);        \
  extern type const __stop_linkarr_##name __asm(  \
      "section$end$__DATA$"                       \
      "__la_" #name);                             \
  UPB_LINKARR_APPEND(name) type UPB_linkarr_internal_empty_##name[1]
#define UPB_LINKARR_START(name) (&__start_linkarr_##name)
#define UPB_LINKARR_STOP(name) (&__stop_linkarr_##name)

#elif defined(_MSC_VER) && defined(__clang__)

/* See:
 *   https://devblogs.microsoft.com/oldnewthing/20181107-00/?p=100155
 *   https://devblogs.microsoft.com/oldnewthing/20181108-00/?p=100165
 *   https://devblogs.microsoft.com/oldnewthing/20181109-00/?p=100175 */

// Usage of __attribute__ here probably means this is Clang-specific, and would
// not work on MSVC.
#define UPB_LINKARR_APPEND(name) \
  __declspec(allocate("la_" #name "$j")) __attribute__((retain, used))
#define UPB_LINKARR_DECLARE(name, type)                               \
  __declspec(allocate("la_" #name "$a")) type __start_linkarr_##name; \
  __declspec(allocate("la_" #name "$z")) type __stop_linkarr_##name;  \
  UPB_LINKARR_APPEND(name) type UPB_linkarr_internal_empty_##name[1] = {0}
#define UPB_LINKARR_START(name) (&__start_linkarr_##name)
#define UPB_LINKARR_STOP(name) (&__stop_linkarr_##name)

#else

// Linker arrays are not supported on this platform.  Make appends a no-op but
// don't define the other macros.
#define UPB_LINKARR_APPEND(name)

#endif