diff options
Diffstat (limited to 'siphash.c')
| -rw-r--r-- | siphash.c | 22 |
1 files changed, 19 insertions, 3 deletions
@@ -104,6 +104,17 @@ * * Return: the 64-bit hash output */ +/* Type-Based Alias Analysis (TBAA) optimisation in gcc 11 and 12 (-flto -O2) + * makes these functions essentially useless by allowing reordering of stores of + * input data across function calls. Not even declaring @in as char pointer is + * enough: disable gcc's interpretation of strict aliasing altogether. See also: + * + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106706 + * https://stackoverflow.com/questions/2958633/gcc-strict-aliasing-and-horror-stories + * https://lore.kernel.org/all/alpine.LFD.2.00.0901121128080.6528__33422.5328093909$1232291247$gmane$org@localhost.localdomain/ + */ +/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */ +__attribute__((optimize("-fno-strict-aliasing"))) /* cppcheck-suppress unusedFunction */ uint64_t siphash_8b(const uint8_t *in, const uint64_t *k) { @@ -123,6 +134,8 @@ uint64_t siphash_8b(const uint8_t *in, const uint64_t *k) * * Return: 32 bits obtained by XORing the two halves of the 64-bit hash output */ +/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */ +__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */ /* cppcheck-suppress unusedFunction */ uint32_t siphash_12b(const uint8_t *in, const uint64_t *k) { @@ -148,9 +161,8 @@ uint32_t siphash_12b(const uint8_t *in, const uint64_t *k) * * Return: the 64-bit hash output */ -#if SIPHASH_20B_NOINLINE -__attribute__((__noinline__)) /* See comment in Makefile */ -#endif +/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */ +__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */ uint64_t siphash_20b(const uint8_t *in, const uint64_t *k) { uint32_t *in32 = (uint32_t *)in; @@ -179,6 +191,8 @@ uint64_t siphash_20b(const uint8_t *in, const uint64_t *k) * * Return: the 64-bit hash output */ +/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */ +__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */ /* cppcheck-suppress unusedFunction */ uint32_t siphash_32b(const uint8_t *in, const uint64_t *k) { @@ -205,6 +219,8 @@ uint32_t siphash_32b(const uint8_t *in, const uint64_t *k) * * Return: 32 bits obtained by XORing the two halves of the 64-bit hash output */ +/* NOLINTNEXTLINE(clang-diagnostic-unknown-attributes) */ +__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */ uint32_t siphash_36b(const uint8_t *in, const uint64_t *k) { uint32_t *in32 = (uint32_t *)in; |