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1/* SPDX-License-Identifier: LGPL-2.1-only OR MIT */2/*3 * rseq/compiler.h4 *5 * Work-around asm goto compiler bugs.6 *7 * (C) Copyright 2021 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>8 */9 10#ifndef RSEQ_COMPILER_H11#define RSEQ_COMPILER_H12 13/*14 * gcc prior to 4.8.2 miscompiles asm goto.15 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=5867016 *17 * gcc prior to 8.1.0 miscompiles asm goto at O1.18 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10390819 *20 * clang prior to version 13.0.1 miscompiles asm goto at O2.21 * https://github.com/llvm/llvm-project/issues/5273522 *23 * Work around these issues by adding a volatile inline asm with24 * memory clobber in the fallthrough after the asm goto and at each25 * label target. Emit this for all compilers in case other similar26 * issues are found in the future.27 */28#define rseq_after_asm_goto() asm volatile ("" : : : "memory")29 30/* Combine two tokens. */31#define RSEQ__COMBINE_TOKENS(_tokena, _tokenb) \32 _tokena##_tokenb33#define RSEQ_COMBINE_TOKENS(_tokena, _tokenb) \34 RSEQ__COMBINE_TOKENS(_tokena, _tokenb)35 36#ifdef __cplusplus37#define rseq_unqual_scalar_typeof(x) \38 std::remove_cv<std::remove_reference<decltype(x)>::type>::type39#else40#define rseq_scalar_type_to_expr(type) \41 unsigned type: (unsigned type)0, \42 signed type: (signed type)043 44/*45 * Use C11 _Generic to express unqualified type from expression. This removes46 * volatile qualifier from expression type.47 */48#define rseq_unqual_scalar_typeof(x) \49 __typeof__( \50 _Generic((x), \51 char: (char)0, \52 rseq_scalar_type_to_expr(char), \53 rseq_scalar_type_to_expr(short), \54 rseq_scalar_type_to_expr(int), \55 rseq_scalar_type_to_expr(long), \56 rseq_scalar_type_to_expr(long long), \57 default: (x) \58 ) \59 )60#endif61 62#endif /* RSEQ_COMPILER_H_ */63