Automatic grid size

src/RegisterBlocking.h

@@ -25,6 +25,7 @@ namespace detail {
         static constexpr auto LoadVector = _mm256_loadu_ps;
         static constexpr auto StoreVector = _mm256_storeu_ps;
         static constexpr auto BroadcastToVector = _mm256_set1_ps;
+        static constexpr unsigned Registers = 16;
     };
 
     struct __m256d_block_wise_config {
@@ -33,6 +34,7 @@ namespace detail {
         static constexpr auto LoadVector = _mm256_loadu_pd;
         static constexpr auto StoreVector = _mm256_storeu_pd;
         static constexpr auto BroadcastToVector = _mm256_set1_pd;
+        static constexpr unsigned Registers = 16;
     };
 
 #ifdef WITH_AVX512
@@ -42,6 +44,7 @@ namespace detail {
         static constexpr auto LoadVector = _mm512_loadu_ps;
         static constexpr auto StoreVector = _mm512_storeu_ps;
         static constexpr auto BroadcastToVector = _mm512_set1_ps;
+        static constexpr unsigned Registers = 32;
     };
 
     struct __m512d_block_wise_config {
@@ -50,13 +53,34 @@ namespace detail {
         static constexpr auto LoadVector = _mm512_loadu_pd;
         static constexpr auto StoreVector = _mm512_storeu_pd;
         static constexpr auto BroadcastToVector = _mm512_set1_pd;
+        static constexpr unsigned Registers = 32;
     };
 #endif
 
+    // maximize = (R * C) / (R + C) for R + R * C < 16 => any fixed r -> largest C with < 16
+    // C = floor ((16 - R) / R)
+
+    constexpr unsigned GetInitialColumnVectors(unsigned R, unsigned Registers) {
+        if (R == 0) return 0;
+        return (unsigned) ((double) (Registers - R) / (double) R);
+    }
+
+    constexpr unsigned GetInitialRows(unsigned Registers) {
+        for(unsigned R = Registers; R > 0; --R) {
+            if(R + R * (R + 1) < Registers) {
+                return R;
+            }
+        }
+        return 0;
+    }
+
+
     template<typename BlockWiseConfig>
     struct ExtendedBlockWiseConfig {
         typedef typename BlockWiseConfig::FloatType FloatType;
         using VectorType = typename BlockWiseConfig::VectorType;
+
+        static constexpr auto Registers = BlockWiseConfig::Registers;
         static constexpr auto LoadVector = BlockWiseConfig::LoadVector;
         static constexpr auto StoreVector = BlockWiseConfig::StoreVector;
         static constexpr auto BroadcastToVector = BlockWiseConfig::BroadcastToVector;
@@ -113,30 +137,16 @@ namespace detail {
 
     };
 
-    template<typename BitWiseConfig, unsigned Rows>
-    struct BestRowRegisterBlocking;
-
-    template<typename BitWiseConfig>
-    struct BestRowRegisterBlocking<BitWiseConfig, 1> : public RegisterBlocking<BitWiseConfig, 1, 15> {
-    };
-    template<typename BitWiseConfig>
-    struct BestRowRegisterBlocking<BitWiseConfig, 2> : public RegisterBlocking<BitWiseConfig, 2, 7> {
-    };
-    template<typename BitWiseConfig>
-    struct BestRowRegisterBlocking<BitWiseConfig, 3> : public RegisterBlocking<BitWiseConfig, 3, 4> {
-    };
-    // maximize = (R * C) / (R + C) for R + R * C < 16 => any fixed r -> largest C with < 16
-    // C = floor ((16 - R) / R)
-
     template<
             // template parameter as struct: otherwise some warning about losing alignment information warning
-            typename BlockWiseConfig = __m256_block_wise_config,
+            typename BlockWiseConfig = __m256_block_wise_config
-            unsigned InitialNumRows = 3, unsigned InitialNumColumnVectors = 4
     >
     struct block_wise {
 
         typedef ExtendedBlockWiseConfig<BlockWiseConfig> bwc;
 
+        static constexpr unsigned InitialNumRows = GetInitialRows(bwc::Registers);
+        static constexpr unsigned InitialNumColumnVectors = GetInitialColumnVectors(InitialNumRows, bwc::Registers);
         static constexpr unsigned NumRows = InitialNumRows;
         static constexpr unsigned NumColumns = InitialNumColumnVectors * bwc::VectorWidth;
 
@@ -248,7 +258,7 @@ namespace detail {
                 consume(k, m_i, m, n, C, A, B);
                 if (CurrentNumRows > 1) {
                     // try with less num rows vectors
-                    iterate_rows<CurrentNumRows - 1, CurrentNumColumnVectors>::iterate(k, m_i, m, n, C, A, B);
+                    iterate_rows<CurrentNumRows - 1, GetInitialColumnVectors(CurrentNumRows - 1, bwc::Registers)>::iterate(k, m_i, m, n, C, A, B);
                 }
                 assert(m_i == m);
             }