Simplify AVX512 algorithm

kimwalisch · Jun 29, 2024 · 5214d3f · 5214d3f
1 parent 6b986a4
commit 5214d3f
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Showing 3 changed files with 14 additions and 13 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,10 @@
+2024-06-29 Kim Walisch <[email protected]>
+
+ Version 3.1
+
+ * Improve AVX512 algorithm for trailing 64 bytes.
+ * AVX512 algorithm does not require AVX512-BITALG extension anymore.
+
 2024-06-27 Kim Walisch <[email protected]>
 
  Version 3.0

diff --git a/benchmark.cpp b/benchmark.cpp
@@ -102,8 +102,7 @@ int main(int argc, char* argv[])
  #if defined(LIBPOPCNT_HAVE_AVX512) && (defined(__AVX512__) || \
  (defined(__AVX512F__) && \
  defined(__AVX512BW__) && \
- defined(__AVX512VPOPCNTDQ__) && \
- defined(__AVX512BITALG__)))
+ defined(__AVX512VPOPCNTDQ__)))
  if (algo.empty() && bytes >= 40)
  algo = "AVX512";
  #endif

diff --git a/libpopcnt.h b/libpopcnt.h
@@ -154,8 +154,7 @@
  ((defined(LIBPOPCNT_HAVE_AVX512) && !(defined(__AVX512__) || \
  (defined(__AVX512F__) && \
  defined(__AVX512BW__) && \
- defined(__AVX512VPOPCNTDQ__) && \
- defined(__AVX512BITALG__)))) || \
+ defined(__AVX512VPOPCNTDQ__)))) || \
  (defined(LIBPOPCNT_HAVE_AVX2) && !defined(__AVX2__)) || \
  (defined(LIBPOPCNT_HAVE_POPCNT) && !defined(__POPCNT__)))
  #define LIBPOPCNT_HAVE_CPUID
@@ -265,7 +264,6 @@ static inline uint64_t popcnt64(uint64_t x)
 #define LIBPOPCNT_BIT_AVX512BW (1 << 30)
 
 /* %ecx bit flags */
-#define LIBPOPCNT_BIT_AVX512_BITALG (1 << 12)
 #define LIBPOPCNT_BIT_AVX512_VPOPCNTDQ (1 << 14)
 #define LIBPOPCNT_BIT_POPCNT (1 << 23)
 
@@ -361,8 +359,7 @@ static inline int get_cpuid(void)
  /* then we add LIBPOPCNT_BIT_AVX512_VPOPCNTDQ to our CPUID flags. */
  if ((abcd[1] & LIBPOPCNT_BIT_AVX512F) == LIBPOPCNT_BIT_AVX512F &&
  (abcd[1] & LIBPOPCNT_BIT_AVX512BW) == LIBPOPCNT_BIT_AVX512BW &&
- (abcd[2] & LIBPOPCNT_BIT_AVX512_VPOPCNTDQ) == LIBPOPCNT_BIT_AVX512_VPOPCNTDQ &&
- (abcd[2] & LIBPOPCNT_BIT_AVX512_BITALG) == LIBPOPCNT_BIT_AVX512_BITALG)
+ (abcd[2] & LIBPOPCNT_BIT_AVX512_VPOPCNTDQ) == LIBPOPCNT_BIT_AVX512_VPOPCNTDQ)
  flags |= LIBPOPCNT_BIT_AVX512_VPOPCNTDQ;
  }
  }
@@ -487,7 +484,7 @@ static inline uint64_t popcnt_avx2(const __m256i* ptr, uint64_t size)
 #include <immintrin.h>
 
 #if __has_attribute(target)
- __attribute__ ((target ("avx512f,avx512bw,avx512vpopcntdq,avx512bitalg")))
+ __attribute__ ((target ("avx512f,avx512bw,avx512vpopcntdq")))
 #endif
 static inline uint64_t popcnt_avx512(const uint8_t* ptr8, uint64_t size)
 {
@@ -528,9 +525,8 @@ static inline uint64_t popcnt_avx512(const uint8_t* ptr8, uint64_t size)
  {
  __mmask64 mask = (__mmask64) (0xffffffffffffffffull >> (i + 64 - size));
  __m512i vec = _mm512_maskz_loadu_epi8(mask, &ptr8[i]);
- __m512i cnt8 = _mm512_popcnt_epi8(vec);
- cnt8 = _mm512_sad_epu8(cnt8, _mm512_setzero_si512());
- cnt = _mm512_add_epi64(cnt, cnt8);
+ vec = _mm512_popcnt_epi64(vec);
+ cnt = _mm512_add_epi64(cnt, vec);
  }
 
  return _mm512_reduce_add_epi64(cnt);
@@ -581,8 +577,7 @@ static uint64_t popcnt(const void* data, uint64_t size)
  #if defined(__AVX512__) || \
  (defined(__AVX512F__) && \
  defined(__AVX512BW__) && \
- defined(__AVX512VPOPCNTDQ__) && \
- defined(__AVX512BITALG__))
+ defined(__AVX512VPOPCNTDQ__))
  /* For tiny arrays AVX512 is not worth it */
  if (i + 40 <= size)
  #else