| From 5fb47367d885a4a32625f09138b306d36ec3769f Mon Sep 17 00:00:00 2001 |
| From: Khem Raj <raj.khem@gmail.com> |
| Date: Sun, 15 Jan 2023 00:16:25 -0800 |
| Subject: [PATCH] Define alignof using _Alignof when using C11 or newer |
| |
| WG14 N2350 made very clear that it is an UB having type definitions |
| within "offsetof" [1]. This patch enhances the implementation of macro |
| alignof to use builtin "_Alignof" to avoid undefined behavior on |
| when using std=c11 or newer |
| |
| clang 16+ has started to flag this [2] |
| |
| Fixes build when using -std >= gnu11 and using clang16+ |
| |
| Older compilers gcc < 4.9 or clang < 8 has buggy _Alignof even though it |
| may support C11, exclude those compilers too |
| |
| [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm |
| [2] https://reviews.llvm.org/D133574 |
| |
| Upstream-Status: Pending |
| Signed-off-by: Khem Raj <raj.khem@gmail.com> |
| --- |
| libiberty/sha1.c | 10 ++++++++++ |
| 1 file changed, 10 insertions(+) |
| |
| diff --git a/libiberty/sha1.c b/libiberty/sha1.c |
| index 6c71e3ebb41..a2caf947d31 100644 |
| --- a/libiberty/sha1.c |
| +++ b/libiberty/sha1.c |
| @@ -229,7 +229,17 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx) |
| if (len >= 64) |
| { |
| #if !_STRING_ARCH_unaligned |
| +/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023 |
| + <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. |
| + clang versions < 8.0.0 have the same bug. */ |
| +#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \ |
| + || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \ |
| + && !defined __clang__) \ |
| + || (defined __clang__ && __clang_major__ < 8)) |
| # define alignof(type) offsetof (struct { char c; type x; }, x) |
| +#else |
| +# define alignof(type) _Alignof(type) |
| +#endif |
| # define UNALIGNED_P(p) (((size_t) p) % alignof (sha1_uint32) != 0) |
| if (UNALIGNED_P (buffer)) |
| while (len > 64) |