Add cmake option to disable AVX

cmake/ConfigureCompiler.cmake

@@ -243,6 +243,12 @@ else()
       -Wno-tautological-pointer-compare
       -Wno-format
       -Woverloaded-virtual)
+    set(USE_AVX ON CACHE BOOL "Enable AVX instructions")
+    if (USE_AVX)
+      add_compile_options(-mavx)
+    else()
+      add_compile_options(-msse4)
+    endif()
     if (USE_CCACHE)
       add_compile_options(
         -Wno-register
@@ -254,7 +260,12 @@ else()
   endif()
   if (GCC)
     add_compile_options(-Wno-pragmas)
-    add_compile_options(-mavx)
+    set(USE_AVX ON CACHE BOOL "Enable AVX instructions")
+    if (USE_AVX)
+      add_compile_options(-mavx)
+    else()
+      add_compile_options(-msse4)
+    endif()
     # Intentionally using builtin memcpy.  G++ does a good job on small memcpy's when the size is known at runtime.
     # If the size is not known, then it falls back on the memcpy that's available at runtime (rte_memcpy, as of this
     # writing; see flow.cpp).

flow/rte_memcpy.h

@@ -50,8 +50,10 @@ extern "C" {
 static force_inline void *
 rte_memcpy(void *dst, const void *src, size_t n);
 
-//#define RTE_MACHINE_CPUFLAG_AVX512F
+#ifdef __AVX__
+//#define RTE_MACHINE_CPUFLAG_AVX512F  -- our g++ is too old for this
 #define RTE_MACHINE_CPUFLAG_AVX2
+#endif
 
 #ifdef RTE_MACHINE_CPUFLAG_AVX512F
 

flow/test_memcpy.cpp

@@ -58,16 +58,16 @@ test_single_memcpy(unsigned int off_src, unsigned int off_dst, size_t size)
 	}
 
 	/* Do the copy */
-	ret = rte_memcpy(dest + off_dst, src + off_src, size);
+	ret = memcpy(dest + off_dst, src + off_src, size);
 	if (ret != (dest + off_dst)) {
-		printf("rte_memcpy() returned %p, not %p\n",
+		printf("memcpy() returned %p, not %p\n",
 		       ret, dest + off_dst);
 	}
 
 	/* Check nothing before offset is affected */
 	for (i = 0; i < off_dst; i++) {
 		if (dest[i] != 0) {
-			printf("rte_memcpy() failed for %u bytes (offsets=%u,%u): "
+			printf("memcpy() failed for %u bytes (offsets=%u,%u): "
 			       "[modified before start of dst].\n",
 			       (unsigned)size, off_src, off_dst);
 			return -1;
@@ -77,7 +77,7 @@ test_single_memcpy(unsigned int off_src, unsigned int off_dst, size_t size)
 	/* Check everything was copied */
 	for (i = 0; i < size; i++) {
 		if (dest[i + off_dst] != src[i + off_src]) {
-			printf("rte_memcpy() failed for %u bytes (offsets=%u,%u): "
+			printf("memcpy() failed for %u bytes (offsets=%u,%u): "
 			       "[didn't copy byte %u].\n",
 			       (unsigned)size, off_src, off_dst, i);
 			return -1;
@@ -87,7 +87,7 @@ test_single_memcpy(unsigned int off_src, unsigned int off_dst, size_t size)
 	/* Check nothing after copy was affected */
 	for (i = size; i < SMALL_BUFFER_SIZE; i++) {
 		if (dest[i + off_dst] != 0) {
-			printf("rte_memcpy() failed for %u bytes (offsets=%u,%u): "
+			printf("memcpy() failed for %u bytes (offsets=%u,%u): "
 			       "[copied too many].\n",
 			       (unsigned)size, off_src, off_dst);
 			return -1;