simd: drop 2 unnecessary instructions (#137)

seanmonstar · May 4, 2023 · f34faf2 · f34faf2
1 parent efcdae7
commit f34faf2
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Showing 2 changed files with 6 additions and 7 deletions.
diff --git a/src/simd/avx2.rs b/src/simd/avx2.rs
@@ -108,10 +108,9 @@ unsafe fn match_header_value_char_32_avx(buf: &[u8]) -> usize {
     let tab = _mm256_cmpeq_epi8(dat, TAB);
     let del = _mm256_cmpeq_epi8(dat, DEL);
     let bit = _mm256_andnot_si256(del, _mm256_or_si256(low, tab));
-    let rev = _mm256_cmpeq_epi8(bit, _mm256_setzero_si256());
-    let res = _mm256_movemask_epi8(rev) as u32;
-
-    res.trailing_zeros() as usize
+    let res = _mm256_movemask_epi8(bit) as u32;
+    // TODO: use .trailing_ones() once MSRV >= 1.46
+    (!res).trailing_zeros() as usize
 }
 
 #[test]

diff --git a/src/simd/sse42.rs b/src/simd/sse42.rs
@@ -97,10 +97,10 @@ unsafe fn match_header_value_char_16_sse(buf: &[u8]) -> usize {
     let tab = _mm_cmpeq_epi8(dat, TAB);
     let del = _mm_cmpeq_epi8(dat, DEL);
     let bit = _mm_andnot_si128(del, _mm_or_si128(low, tab));
-    let rev = _mm_cmpeq_epi8(bit, _mm_setzero_si128());
-    let res = _mm_movemask_epi8(rev) as u16;
+    let res = _mm_movemask_epi8(bit) as u16;
 
-    res.trailing_zeros() as usize
+    // TODO: use .trailing_ones() once MSRV >= 1.46
+    (!res).trailing_zeros() as usize
 }
 
 #[test]