0008-Define-alignof-using-_Alignof-when-using-C11-or-newe.patch 1.8 KB

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  1. From e649db1664af981cc87f966aef6c5365ae234547 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] Define alignof using _Alignof when using C11 or newer
  5. WG14 N2350 made very clear that it is an UB having type definitions
  6. within "offsetof" [1]. This patch enhances the implementation of macro
  7. alignof to use builtin "_Alignof" to avoid undefined behavior on
  8. when using std=c11 or newer
  9. clang 16+ has started to flag this [2]
  10. Fixes build when using -std >= gnu11 and using clang16+
  11. Older compilers gcc < 4.9 or clang < 8 has buggy _Alignof even though it
  12. may support C11, exclude those compilers too
  13. [1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm
  14. [2] https://reviews.llvm.org/D133574
  15. Upstream-Status: Pending
  16. Signed-off-by: Khem Raj <raj.khem@gmail.com>
  17. ---
  18. libiberty/sha1.c | 10 ++++++++++
  19. 1 file changed, 10 insertions(+)
  20. diff --git a/libiberty/sha1.c b/libiberty/sha1.c
  21. index 504f06d3b9b..790ada82443 100644
  22. --- a/libiberty/sha1.c
  23. +++ b/libiberty/sha1.c
  24. @@ -229,7 +229,17 @@ sha1_process_bytes (const void *buffer, size_t len, struct sha1_ctx *ctx)
  25. if (len >= 64)
  26. {
  27. #if !_STRING_ARCH_unaligned
  28. +/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023
  29. + <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.
  30. + clang versions < 8.0.0 have the same bug. */
  31. +#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
  32. + || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
  33. + && !defined __clang__) \
  34. + || (defined __clang__ && __clang_major__ < 8))
  35. # define alignof(type) offsetof (struct { char c; type x; }, x)
  36. +#else
  37. +# define alignof(type) _Alignof(type)
  38. +#endif
  39. # define UNALIGNED_P(p) (((size_t) p) % alignof (sha1_uint32) != 0)
  40. if (UNALIGNED_P (buffer))
  41. while (len > 64)