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 /* Combine two tokens. */
31 #define RSEQ__COMBINE_TOKENS(_tokena, _tokenb) \
32 _tokena##_tokenb
33 #define RSEQ_COMBINE_TOKENS(_tokena, _tokenb) \
34 RSEQ__COMBINE_TOKENS(_tokena, _tokenb)
35
36 #ifdef __cplusplus
37 #define rseq_unqual_scalar_typeof(x) \
38 std::remove_cv<std::remove_reference<decltype(x)>::type>::type
39 #else
40 #define rseq_scalar_type_to_expr(type) \
41 unsigned type: (unsigned type)0, \
42 signed type: (signed type)0
43
44 /*
45 * Use C11 _Generic to express unqualified type from expression. This removes
46 * 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 #endif
61
62 #endif /* RSEQ_COMPILER_H_ */
63
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.