include/rseq/compiler.h

   1 /* SPDX-License-Identifier: LGPL-2.1-only OR MIT */
   2 /*
   3  * rseq/compiler.h
   4  *
   5  * Work-around asm goto compiler bugs.
   6  *
   7  * (C) Copyright 2021 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   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 #endif  /* RSEQ_COMPILER_H_ */