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/* SPDX-License-Identifier: LGPL-2.1-only OR MIT */
/*
* rseq/compiler.h
*
* Work-around asm goto compiler bugs.
*
* (C) Copyright 2021 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*/
#ifndef RSEQ_COMPILER_H
#define RSEQ_COMPILER_H
/*
* gcc prior to 4.8.2 miscompiles asm goto.
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
*
* gcc prior to 8.1.0 miscompiles asm goto at O1.
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908
*
* clang prior to version 13.0.1 miscompiles asm goto at O2.
* https://github.com/llvm/llvm-project/issues/52735
*
* Work around these issues by adding a volatile inline asm with
* memory clobber in the fallthrough after the asm goto and at each
* label target. Emit this for all compilers in case other similar
* issues are found in the future.
*/
#define rseq_after_asm_goto() asm volatile ("" : : : "memory")
/* Combine two tokens. */
#define RSEQ__COMBINE_TOKENS(_tokena, _tokenb) \
_tokena##_tokenb
#define RSEQ_COMBINE_TOKENS(_tokena, _tokenb) \
RSEQ__COMBINE_TOKENS(_tokena, _tokenb)
#ifdef __cplusplus
#define rseq_unqual_scalar_typeof(x) \
std::remove_cv<std::remove_reference<decltype(x)>::type>::type
#else
#define rseq_scalar_type_to_expr(type) \
unsigned type: (unsigned type)0, \
signed type: (signed type)0
/*
* Use C11 _Generic to express unqualified type from expression. This removes
* volatile qualifier from expression type.
*/
#define rseq_unqual_scalar_typeof(x) \
__typeof__( \
_Generic((x), \
char: (char)0, \
rseq_scalar_type_to_expr(char), \
rseq_scalar_type_to_expr(short), \
rseq_scalar_type_to_expr(int), \
rseq_scalar_type_to_expr(long), \
rseq_scalar_type_to_expr(long long), \
default: (x) \
) \
)
#endif
#endif /* RSEQ_COMPILER_H_ */
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