clang/lib/Headers/llvm_libc_wrappers/stdio.h

   1 //===-- Wrapper for C standard stdio.h declarations on the GPU ------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #if !defined(_OPENMP) && !defined(__HIP__) && !defined(__CUDA__)
  10 #error "This file is for GPU offloading compilation only"
  11 #endif
  12
  13 #include_next <stdio.h>
  14
  15 // In some old versions of glibc, other standard headers sometimes define
  16 // special macros (e.g., __need_FILE) before including stdio.h to cause stdio.h
  17 // to produce special definitions.  Future includes of stdio.h when those
  18 // special macros are undefined are expected to produce the normal definitions
  19 // from stdio.h.
  20 //
  21 // We do not apply our include guard (__CLANG_LLVM_LIBC_WRAPPERS_STDIO_H__)
  22 // unconditionally to the above include_next.  Otherwise, after an occurrence of
  23 // the first glibc stdio.h use case described above, the include_next would be
  24 // skipped for remaining includes of stdio.h, leaving required symbols
  25 // undefined.
  26 //
  27 // We make the following assumptions to handle all use cases:
  28 //
  29 // 1. If the above include_next produces special glibc definitions, then (a) it
  30 //    does not produce the normal definitions that we must intercept below, (b)
  31 //    the current file was included from a glibc header that already defined
  32 //    __GLIBC__ (usually by including glibc's <features.h>), and (c) the above
  33 //    include_next does not define _STDIO_H.  In that case, we skip the rest of
  34 //    the current file and don't guard against future includes.
  35 // 2. If the above include_next produces the normal stdio.h definitions, then
  36 //    either (a) __GLIBC__ is not defined because C headers are from some other
  37 //    libc implementation or (b) the above include_next defines _STDIO_H to
  38 //    prevent the above include_next from having any effect in the future.
  39 #if !defined(__GLIBC__) || defined(_STDIO_H)
  40
  41 #ifndef __CLANG_LLVM_LIBC_WRAPPERS_STDIO_H__
  42 #define __CLANG_LLVM_LIBC_WRAPPERS_STDIO_H__
  43
  44 #if __has_include(<llvm-libc-decls/stdio.h>)
  45
  46 #if defined(__HIP__) || defined(__CUDA__)
  47 #define __LIBC_ATTRS __attribute__((device))
  48 #endif
  49
  50 // Some headers provide these as macros. Temporarily undefine them so they do
  51 // not conflict with any definitions for the GPU.
  52
  53 #pragma push_macro("stdout")
  54 #pragma push_macro("stdin")
  55 #pragma push_macro("stderr")
  56
  57 #undef stdout
  58 #undef stderr
  59 #undef stdin
  60
  61 #pragma omp begin declare target
  62
  63 #include <llvm-libc-decls/stdio.h>
  64
  65 #pragma omp end declare target
  66
  67 #undef __LIBC_ATTRS
  68
  69 // Restore the original macros when compiling on the host.
  70 #if !defined(__NVPTX__) && !defined(__AMDGPU__)
  71 #pragma pop_macro("stdout")
  72 #pragma pop_macro("stderr")
  73 #pragma pop_macro("stdin")
  74 #endif
  75
  76 #endif
  77
  78 #endif // __CLANG_LLVM_LIBC_WRAPPERS_STDIO_H__
  79
  80 #endif