Fix selection of IntSimdMatrix method

Commit d36231e did not distinguish
between AVX and AVX2, so AVX2 code was enabled for IntSimdMatrix
even when only AVX was supported.

This resulted in an illegal instruction.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

src/arch/simddetect.cpp

@@ -125,10 +125,15 @@ SIMDDetect::SIMDDetect() {
   // Select code for calculation of dot product based on autodetection.
   if (false) {
     // This is a dummy to support conditional compilation.
+#if defined(AVX2)
+  } else if (avx2_available_) {
+    // AVX2 detected.
+    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixAVX2);
+#endif
 #if defined(AVX)
   } else if (avx_available_) {
     // AVX detected.
-    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixAVX2);
+    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixSSE);
 #endif
 #if defined(SSE4_1)
   } else if (sse_available_) {
@@ -152,10 +157,16 @@ void SIMDDetect::Update() {
     // Native optimized code selected by config variable.
     SetDotProduct(DotProductNative);
     dotproduct_method = "native";
+#if defined(AVX2)
+  } else if (!strcmp(dotproduct.string(), "avx2")) {
+    // AVX2 selected by config variable.
+    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixAVX2);
+    dotproduct_method = "avx2";
+#endif
 #if defined(AVX)
   } else if (!strcmp(dotproduct.string(), "avx")) {
     // AVX selected by config variable.
-    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixAVX2);
+    SetDotProduct(DotProductAVX, &IntSimdMatrix::intSimdMatrixSSE);
     dotproduct_method = "avx";
 #endif
 #if defined(SSE4_1)