Reduce SIMD register count from 32 to 16

[stockfish] / src / nnue / nnue_feature_transformer.h

diff --git a/src/nnue/nnue_feature_transformer.h b/src/nnue/nnue_feature_transformer.h
index 0af0ed96cc5a1446a98150f1d9d6b1ba9f3b4c65..902918b2c6ff433656a110c9714481a7b72eac77 100644 (file)
--- a/src/nnue/nnue_feature_transformer.h
+++ b/src/nnue/nnue_feature_transformer.h
@@ -69,7 +69,7 @@ namespace Stockfish::Eval::NNUE {
   #define vec_add_psqt_32(a,b) _mm256_add_epi32(a,b)
   #define vec_sub_psqt_32(a,b) _mm256_sub_epi32(a,b)
   #define vec_zero_psqt() _mm256_setzero_si256()
-  #define NumRegistersSIMD 32
+  #define NumRegistersSIMD 16
   #define MaxChunkSize 64
 
   #elif USE_AVX2
@@ -327,9 +327,9 @@ namespace Stockfish::Eval::NNUE {
           for (IndexType j = 0; j < HalfDimensions / 2; ++j) {
               BiasType sum0 = accumulation[static_cast<int>(perspectives[p])][j + 0];
               BiasType sum1 = accumulation[static_cast<int>(perspectives[p])][j + HalfDimensions / 2];
-              sum0 = std::max<int>(0, std::min<int>(127, sum0));
-              sum1 = std::max<int>(0, std::min<int>(127, sum1));
-              output[offset + j] = static_cast<OutputType>(sum0 * sum1 / 128);
+              sum0 = std::clamp<BiasType>(sum0, 0, 127);
+              sum1 = std::clamp<BiasType>(sum1, 0, 127);
+              output[offset + j] = static_cast<OutputType>(unsigned(sum0 * sum1) / 128);
           }
 
 #endif