Use _mm_set1_epi{32,64x} to init mask in x86-64 [cz]asum

for skylake kernels. This is the same method as used in [sd]asum. _mm_set1_epi64x was commented out for zasum, but has the advantage of avoiding possible undefined behaviour (using an uninitialized variable), optimized out by NVHPC and icx. The new code works fine with those compilers. For GCC 12.3 the generated code is identical; no matter what method you use, the compiler optimizes the code into a compile-time constant, there is no performance benefit using mm_cmpeq_epi8 since the corresponding instruction (VPCMPEQB) isn't actually generated!
martin-frbg · Nov 19, 2023 · c34e2cf · c34e2cf
1 parent 22aa401
commit c34e2cf
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 13 deletions.
diff --git a/kernel/x86_64/casum_microk_skylakex-2.c b/kernel/x86_64/casum_microk_skylakex-2.c
@@ -2,10 +2,9 @@
 #ifdef __NVCOMPILER
 #define NVCOMPVERS ( __NVCOMPILER_MAJOR__ * 100 + __NVCOMPILER_MINOR__ )
 #endif
-#if ((( defined(__GNUC__)  && __GNUC__   > 6 && defined(__AVX512CD__)) || (defined(__clang__) && (__clang_major__ >= 9 &&__clang_major__ !=17)) || ( defined(__NVCOMPILER) && NVCOMPVERS >= 2309)))
+#if ((( defined(__GNUC__)  && __GNUC__   > 6 && defined(__AVX512CD__)) || (defined(__clang__) && __clang_major__ >= 9)) || (defined(__NVCOMPILER) && NVCOMPVERS >= 2203))
 
-#if (!(defined(__NVCOMPILER) ))
-//&& NVCOMPVERS < 2309))
+#if (!(defined(__NVCOMPILER) && NVCOMPVERS < 2203))
 
 #define HAVE_CASUM_KERNEL 1
 
@@ -21,15 +20,14 @@ static FLOAT casum_kernel(BLASLONG n, FLOAT *x)
 
     if (n2 < 64) {
         __m128 accum_10, accum_11, accum_12, accum_13;
-        __m128 abs_mask1 = abs_mask1;
+        __m128 abs_mask1;
 
         accum_10 = _mm_setzero_ps();
         accum_11 = _mm_setzero_ps();
         accum_12 = _mm_setzero_ps();
         accum_13 = _mm_setzero_ps();
 
-        abs_mask1 = (__m128)_mm_cmpeq_epi8((__m128i) abs_mask1, (__m128i) abs_mask1);
-        abs_mask1 = (__m128)_mm_srli_epi32((__m128i) abs_mask1, 1);
+        abs_mask1 = (__m128)_mm_set1_epi32(0x7fffffff);
 
         _mm_prefetch(&x1[0], _MM_HINT_T0);
 

diff --git a/kernel/x86_64/zasum_microk_skylakex-2.c b/kernel/x86_64/zasum_microk_skylakex-2.c
@@ -2,10 +2,9 @@
 #ifdef __NVCOMPILER
 #define NVCOMPVERS ( __NVCOMPILER_MAJOR__ * 100 + __NVCOMPILER_MINOR__ )
 #endif
-#if ((( defined(__GNUC__)  && __GNUC__   > 6 && defined(__AVX512CD__)) || (defined(__clang__) && ( __clang_major__ >= 9 && __clang_major__ != 17)) || (defined(__NVCOMPILER) && NVCOMPVERS >= 2309)))
+#if ((( defined(__GNUC__)  && __GNUC__   > 6 && defined(__AVX512CD__)) || (defined(__clang__) && __clang_major__ >= 9)) || (defined(__NVCOMPILER) && NVCOMPVERS >= 2203))
 
-#if (!(defined(__NVCOMPILER) ))
-//&& NVCOMPVERS < 2309))
+#if (!(defined(__NVCOMPILER) && NVCOMPVERS < 2203))
 
 #define HAVE_ZASUM_KERNEL 1
 
@@ -22,16 +21,14 @@ static FLOAT zasum_kernel(BLASLONG n, FLOAT *x)
 
     if (n2 < 32) {
         __m128d accum_10, accum_11, accum_12, accum_13;
-        __m128d abs_mask1 = abs_mask1;
+        __m128d abs_mask1;
 
         accum_10 = _mm_setzero_pd();
         accum_11 = _mm_setzero_pd();
         accum_12 = _mm_setzero_pd();
         accum_13 = _mm_setzero_pd();
 
-        // abs_mask1 = (__m128d)_mm_set1_epi64x(0x7fffffffffffffff);
-        abs_mask1 = (__m128d)_mm_cmpeq_epi8((__m128i) abs_mask1, (__m128i) abs_mask1);
-        abs_mask1 = (__m128d)_mm_srli_epi64((__m128i) abs_mask1, 1);
+        abs_mask1 = (__m128d)_mm_set1_epi64x(0x7fffffffffffffff);
 
         _mm_prefetch(&x1[0], _MM_HINT_T0);
         if (n2 >= 16){