| 1 | /* SPDX-License-Identifier: LGPL-2.1-only OR MIT */ |
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| 2 | /* |
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| 3 | * rseq/compiler.h |
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| 4 | * |
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| 5 | * Work-around asm goto compiler bugs. |
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| 6 | * |
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| 7 | * (C) Copyright 2021 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
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| 8 | */ |
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| 9 | |
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| 10 | #ifndef RSEQ_COMPILER_H |
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| 11 | #define RSEQ_COMPILER_H |
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| 12 | |
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| 13 | /* |
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| 14 | * gcc prior to 4.8.2 miscompiles asm goto. |
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| 15 | * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 |
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| 16 | * |
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| 17 | * gcc prior to 8.1.0 miscompiles asm goto at O1. |
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| 18 | * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908 |
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| 19 | * |
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| 20 | * clang prior to version 13.0.1 miscompiles asm goto at O2. |
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| 21 | * https://github.com/llvm/llvm-project/issues/52735 |
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| 22 | * |
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| 23 | * Work around these issues by adding a volatile inline asm with |
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| 24 | * memory clobber in the fallthrough after the asm goto and at each |
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| 25 | * label target. Emit this for all compilers in case other similar |
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| 26 | * issues are found in the future. |
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| 27 | */ |
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| 28 | #define rseq_after_asm_goto() asm volatile ("" : : : "memory") |
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| 29 | |
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| 30 | /* Combine two tokens. */ |
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| 31 | #define RSEQ__COMBINE_TOKENS(_tokena, _tokenb) \ |
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| 32 | _tokena##_tokenb |
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| 33 | #define RSEQ_COMBINE_TOKENS(_tokena, _tokenb) \ |
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| 34 | RSEQ__COMBINE_TOKENS(_tokena, _tokenb) |
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| 35 | |
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| 36 | #ifdef __cplusplus |
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| 37 | #define rseq_unqual_scalar_typeof(x) \ |
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| 38 | std::remove_cv<std::remove_reference<decltype(x)>::type>::type |
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| 39 | #else |
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| 40 | #define rseq_scalar_type_to_expr(type) \ |
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| 41 | unsigned type: (unsigned type)0, \ |
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| 42 | signed type: (signed type)0 |
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| 43 | |
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| 44 | /* |
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| 45 | * Use C11 _Generic to express unqualified type from expression. This removes |
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| 46 | * volatile qualifier from expression type. |
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| 47 | */ |
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| 48 | #define rseq_unqual_scalar_typeof(x) \ |
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| 49 | __typeof__( \ |
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| 50 | _Generic((x), \ |
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| 51 | char: (char)0, \ |
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| 52 | rseq_scalar_type_to_expr(char), \ |
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| 53 | rseq_scalar_type_to_expr(short), \ |
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| 54 | rseq_scalar_type_to_expr(int), \ |
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| 55 | rseq_scalar_type_to_expr(long), \ |
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| 56 | rseq_scalar_type_to_expr(long long), \ |
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| 57 | default: (x) \ |
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| 58 | ) \ |
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| 59 | ) |
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| 60 | #endif |
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| 61 | |
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| 62 | #endif /* RSEQ_COMPILER_H_ */ |
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| 63 | |
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