From a04e825e776ebb5684a94a310b1dc2c54e515d0c Mon Sep 17 00:00:00 2001 From: "Anton A. Melnikov" Date: Wed, 12 Feb 2025 20:22:45 +0300 Subject: [PATCH] Use valgrind-safe code to find a number of rightmost zero bytes. --- src/include/common/hashfn_unstable.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/src/include/common/hashfn_unstable.h b/src/include/common/hashfn_unstable.h index e07c0226c1f..82158f0d9c3 100644 --- a/src/include/common/hashfn_unstable.h +++ b/src/include/common/hashfn_unstable.h @@ -255,7 +255,7 @@ static inline size_t fasthash_accum_cstring_aligned(fasthash_state *hs, const char *str) { const char *const start = str; - size_t remainder; + size_t remainder = 0; uint64 zero_byte_low; Assert(PointerIsAligned(start, uint64)); @@ -291,11 +291,18 @@ fasthash_accum_cstring_aligned(fasthash_state *hs, const char *str) } /* - * The byte corresponding to the NUL will be 0x80, so the rightmost bit - * position will be in the range 7, 15, ..., 63. Turn this into byte - * position by dividing by 8. + * The byte corresponding to the NUL terminator will be the rightmost 0x80. + * pAll zero bytes to the right of it correspond to the tail of the string. + * It remains to count them. */ - remainder = pg_rightmost_one_pos64(zero_byte_low) / BITS_PER_BYTE; + while ((zero_byte_low & 0xFF) == 0) + { + zero_byte_low >>= 8; + ++remainder; + } + + Assert(remainder != 0); + fasthash_accum(hs, str, remainder); str += remainder; -- 2.48.1