From bac26e0c7ee900246d454dd98de45b3ecefc15ec Mon Sep 17 00:00:00 2001 From: "Anton A. Melnikov" Date: Thu, 16 Jan 2025 02:56:52 +0300 Subject: [PATCH] Use valgrind-safe code to find a number of rightmost zero bytes. --- src/include/common/hashfn_unstable.h | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/src/include/common/hashfn_unstable.h b/src/include/common/hashfn_unstable.h index a09c0b7d5ce..fa9b954c6b9 100644 --- a/src/include/common/hashfn_unstable.h +++ b/src/include/common/hashfn_unstable.h @@ -299,15 +299,21 @@ fasthash_accum_cstring_aligned(fasthash_state *hs, const char *str) if (firstbyte64(chunk) != 0) { - size_t remainder; + size_t remainder = 0; uint64 mask; /* - * The byte corresponding to the NUL will be 0x80, so the rightmost - * bit position will be in the range 15, 23, ..., 63. Turn this into - * byte position by dividing by 8. + * The byte corresponding to the NUL terminator will be the rightmost 0x80. + * All 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); /* * Create a mask for the remaining bytes so we can combine them into -- 2.48.1