From aed317b83f012dea78d5e67f3e6e27af3e4141b2 Mon Sep 17 00:00:00 2001 From: Raghuveer Devulapalli Date: Mon, 16 Jun 2025 21:16:43 -0700 Subject: [PATCH v1] Fix incorrect checksum calculation when build with -O0 opt flag bug: fix checksum errors caused by undefined AVX-512 bits Problem: - _mm512_castsi128_si512 leaves upper 384 bits in undefined state - Results in checksum failures when building PostgreSQL with clang -O0 Solution: - Use _mm512_zextsi128_si512 to explicitly zero-extend __m128i to __m512i --- src/port/pg_crc32c_sse42.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/port/pg_crc32c_sse42.c b/src/port/pg_crc32c_sse42.c index 9af3474a6ca..1a717255355 100644 --- a/src/port/pg_crc32c_sse42.c +++ b/src/port/pg_crc32c_sse42.c @@ -123,7 +123,7 @@ pg_comp_crc32c_avx512(pg_crc32c crc, const void *data, size_t len) __m512i k; k = _mm512_broadcast_i32x4(_mm_setr_epi32(0x740eef02, 0, 0x9e4addf8, 0)); - x0 = _mm512_xor_si512(_mm512_castsi128_si512(_mm_cvtsi32_si128(crc0)), x0); + x0 = _mm512_xor_si512(_mm512_zextsi128_si512(_mm_cvtsi32_si128(crc0)), x0); buf += 64; /* Main loop. */ -- 2.43.0