include/rseq/compiler.h

   1 /* SPDX-License-Identifier: MIT */
   2 /* SPDX-FileCopyrightText: 2021 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> */
   3
   4 /*
   5  * rseq/compiler.h
   6  *
   7  * Work-around asm goto compiler bugs.
   8  */
   9
  10 #ifndef RSEQ_COMPILER_H
  11 #define RSEQ_COMPILER_H
  12
  13 /*
  14  * gcc prior to 4.8.2 miscompiles asm goto.
  15  * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
  16  *
  17  * gcc prior to 8.1.0 miscompiles asm goto at O1.
  18  * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908
  19  *
  20  * clang prior to version 13.0.1 miscompiles asm goto at O2.
  21  * https://github.com/llvm/llvm-project/issues/52735
  22  *
  23  * Work around these issues by adding a volatile inline asm with
  24  * memory clobber in the fallthrough after the asm goto and at each
  25  * label target.  Emit this for all compilers in case other similar
  26  * issues are found in the future.
  27  */
  28 #define rseq_after_asm_goto()   asm volatile ("" : : : "memory")
  29
  30 #if defined(__SIZEOF_LONG__)
  31 #define RSEQ_BITS_PER_LONG      (__SIZEOF_LONG__ * 8)
  32 #elif defined(_LP64)
  33 #define RSEQ_BITS_PER_LONG      64
  34 #else
  35 #define RSEQ_BITS_PER_LONG      32
  36 #endif
  37
  38 #endif  /* RSEQ_COMPILER_H_ */