Patrick Williams | b9af875 | 2023-01-30 13:28:01 -0600 | [diff] [blame^] | 1 | From 48906e1038e469b429aa35d0f967730a929c3880 Mon Sep 17 00:00:00 2001 |
| 2 | From: Khem Raj <raj.khem@gmail.com> |
| 3 | Date: Sun, 15 Jan 2023 00:16:25 -0800 |
| 4 | Subject: [PATCH 8/8] 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_slot 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 | gnulib needs this fix and then it will be applied to downstream packages |
| 19 | like gdb [3] |
| 20 | |
| 21 | [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm |
| 22 | [2] https://reviews.llvm.org/D133574 |
| 23 | [3] https://public-inbox.org/bug-gnulib/20230114232744.215167-1-raj.khem@gmail.com/T/#u |
| 24 | |
| 25 | Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=2d404c7dd974cc65f894526f4a1b76bc1dcd8d82] |
| 26 | Signed-off-by: Khem Raj <raj.khem@gmail.com> |
| 27 | --- |
| 28 | libiberty/sha1.c | 10 ++++++++++ |
| 29 | 1 file changed, 10 insertions(+) |
| 30 | |
| 31 | diff --git a/libiberty/sha1.c b/libiberty/sha1.c |
| 32 | index 504f06d3b9b..790ada82443 100644 |
| 33 | --- a/libiberty/sha1.c |
| 34 | +++ b/libiberty/sha1.c |
| 35 | @@ -229,7 +229,17 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx) |
| 36 | if (len >= 64) |
| 37 | { |
| 38 | #if !_STRING_ARCH_unaligned |
| 39 | +/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023 |
| 40 | + <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. |
| 41 | + clang versions < 8.0.0 have the same bug. */ |
| 42 | +#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \ |
| 43 | + || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \ |
| 44 | + && !defined __clang__) \ |
| 45 | + || (defined __clang__ && __clang_major__ < 8)) |
| 46 | # define alignof(type) offsetof (struct { char c; type x; }, x) |
| 47 | +#else |
| 48 | +# define alignof(type) _Alignof(type) |
| 49 | +#endif |
| 50 | # define UNALIGNED_P(p) (((size_t) p) % alignof (sha1_uint32) != 0) |
| 51 | if (UNALIGNED_P (buffer)) |
| 52 | while (len > 64) |
| 53 | -- |
| 54 | 2.39.0 |
| 55 | |