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1e241970 | 1 | From d479020609329cdc7fa3675bc3daf072401fefae Mon Sep 17 00:00:00 2001 |
ae2b71ca KR |
2 | From: Khem Raj <raj.khem@gmail.com> |
3 | Date: Sun, 15 Jan 2023 00:16:25 -0800 | |
4 | Subject: [PATCH] Define alignof using _Alignof when using C11 or newer | |
5 | ||
6 | WG14 N2350 made very clear that it is an UB having type definitions | |
7 | within "offsetof" [1]. This patch enhances the implementation of macro | |
8 | alignof to use builtin "_Alignof" to avoid undefined behavior on | |
9 | when using std=c11 or newer | |
10 | ||
11 | clang 16+ has started to flag this [2] | |
12 | ||
13 | Fixes build when using -std >= gnu11 and using clang16+ | |
14 | ||
15 | Older compilers gcc < 4.9 or clang < 8 has buggy _Alignof even though it | |
16 | may support C11, exclude those compilers too | |
17 | ||
18 | [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm | |
19 | [2] https://reviews.llvm.org/D133574 | |
20 | ||
21 | Upstream-Status: Pending | |
22 | Signed-off-by: Khem Raj <raj.khem@gmail.com> | |
23 | --- | |
24 | libiberty/sha1.c | 10 ++++++++++ | |
25 | 1 file changed, 10 insertions(+) | |
26 | ||
27 | diff --git a/libiberty/sha1.c b/libiberty/sha1.c | |
795af50e | 28 | index 49e8e0b6c2b..72de5cc8ad6 100644 |
ae2b71ca KR |
29 | --- a/libiberty/sha1.c |
30 | +++ b/libiberty/sha1.c | |
795af50e | 31 | @@ -234,7 +234,17 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx) |
ae2b71ca KR |
32 | if (len >= 64) |
33 | { | |
34 | #if !_STRING_ARCH_unaligned | |
35 | +/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023 | |
36 | + <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. | |
37 | + clang versions < 8.0.0 have the same bug. */ | |
38 | +#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \ | |
39 | + || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \ | |
40 | + && !defined __clang__) \ | |
41 | + || (defined __clang__ && __clang_major__ < 8)) | |
42 | # define alignof(type) offsetof (struct { char c; type x; }, x) | |
43 | +#else | |
44 | +# define alignof(type) _Alignof(type) | |
45 | +#endif | |
46 | # define UNALIGNED_P(p) (((size_t) p) % alignof (sha1_uint32) != 0) | |
47 | if (UNALIGNED_P (buffer)) | |
48 | while (len > 64) |