Query AVX2 and AVX512 capability for runtime cpu selection

Author: martin-frbg

driver/others/dynamic.c

@@ -304,9 +304,47 @@ int support_avx(){
 #endif
 }
 
+int support_avx2(){
+#ifndef NO_AVX2
+  int eax, ebx, ecx=0, edx;
+  int ret=0;
+
+  if (!support_avx) 
+    return 0;
+  cpuid(7, &eax, &ebx, &ecx, &edx);
+  if((ebx & (1<<7)) != 0)
+      ret=1;  //OS supports AVX2
+  return ret;
+#else
+  return 0;
+#endif
+}
+
+int support_avx512(){
+#ifndef NO_AVX512
+  int eax, ebx, ecx, edx;
+  int ret=0;
+
+  if (!support_avx) 
+    return 0;
+  cpuid(7, &eax, &ebx, &ecx, &edx);
+  if((ebx & (1<<7)) != 1){
+      ret=0;  //OS does not even support AVX2
+  }
+  if((ebx & (1<<31)) != 0){
+      ret=1;  //OS supports AVX512VL
+  }
+  return ret;
+#else
+  return 0;
+#endif
+}
+
 extern void openblas_warning(int verbose, const char * msg);
 #define FALLBACK_VERBOSE 1
 #define NEHALEM_FALLBACK "OpenBLAS : Your OS does not support AVX instructions. OpenBLAS is using Nehalem kernels as a fallback, which may give poorer performance.\n"
+#define SANDYBRIDGE_FALLBACK "OpenBLAS : Your OS does not support AVX2 instructions. OpenBLAS is using Sandybridge kernels as a fallback, which may give poorer performance.\n"
+#define HASWELL_FALLBACK "OpenBLAS : Your OS does not support AVX512 instructions. OpenBLAS is using Haswell kernels as a fallback, which may give poorer performance.\n"
 #define BARCELONA_FALLBACK "OpenBLAS : Your OS does not support AVX instructions. OpenBLAS is using Barcelona kernels as a fallback, which may give poorer performance.\n"
 
 static int get_vendor(void){
@@ -403,18 +441,24 @@ static gotoblas_t *get_coretype(void){
 	}
 	//Intel Haswell
 	if (model == 12 || model == 15) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
 	}
 	//Intel Broadwell
 	if (model == 13) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
@@ -424,27 +468,36 @@ static gotoblas_t *get_coretype(void){
       case 4:
 		//Intel Haswell
 	if (model == 5 || model == 6) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
 	}
 	//Intel Broadwell
 	if (model == 7 || model == 15) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
 	}
 	//Intel Skylake
 	if (model == 14) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
@@ -457,40 +510,50 @@ static gotoblas_t *get_coretype(void){
       case 5:
 	//Intel Broadwell
 	if (model == 6) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
 	}
 	if (model == 5) {	
 	// Intel Skylake X
-#ifndef NO_AVX512
-	  return &gotoblas_SKYLAKEX;
-#else		
-	  if(support_avx())
+          if (support_avx512()) 
+	    return &gotoblas_SKYLAKEX;
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else {
-	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
-	    return &gotoblas_NEHALEM;
-	  }
-#endif		
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
+          openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
+          return &gotoblas_NEHALEM;
+          }
 	}
 	//Intel Skylake
 	if (model == 14) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
 	}
 	//Intel Phi Knights Landing
 	if (model == 7) {
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }
@@ -503,26 +566,26 @@ static gotoblas_t *get_coretype(void){
       case 6:
         if (model == 6) {
           // Cannon Lake
-#ifndef NO_AVX512
-	  return &gotoblas_SKYLAKEX;
-#else
-	  if(support_avx())
-#ifndef NO_AVX2
-	  return &gotoblas_HASWELL;
-#else
-	  return &gotoblas_SANDYBRIDGE;
-#endif
-	  else
-	  return &gotoblas_NEHALEM;
-#endif			
+	  if(support_avx2())
+	    return &gotoblas_HASWELL;
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
+	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
+	    return &gotoblas_NEHALEM;
+	  }
         }
         return NULL;  
       case 9:
       case 8:
 	if (model == 14 ) { // Kaby Lake
-	  if(support_avx())
+	  if(support_avx2())
 	    return &gotoblas_HASWELL;
-	  else{
+	  if(support_avx()) {
+	    openblas_warning(FALLBACK_VERBOSE, SANDYBRIDGE_FALLBACK);
+	    return &gotoblas_SANDYBRIDGE;
+	  } else {
 	    openblas_warning(FALLBACK_VERBOSE, NEHALEM_FALLBACK);
 	    return &gotoblas_NEHALEM; //OS doesn't support AVX. Use old kernels.
 	  }