Index: gcc/gcc/config/i386/i386.c
===================================================================
--- gcc.orig/gcc/config/i386/i386.c
+++ gcc/gcc/config/i386/i386.c
@@ -4506,11 +4506,15 @@ ix86_pass_by_reference (CUMULATIVE_ARGS 
 	    }
 	}
 
-      /* __m128 is passed by reference.  */
-      /* ??? How to handle complex?  For now treat them as structs,
-	 and pass them by reference if they're too large.  */
-      if (GET_MODE_SIZE (mode) > 8)
-	return true;
+      if (COMPLEX_MODE_P (mode) || VECTOR_MODE_P (mode))
+        return true;
+      switch (GET_MODE_SIZE (mode))
+        {
+          case 1: case 2: case 4: case 8:
+            break;
+          default:
+            return true;
+        }
     }
   else if (TARGET_64BIT && type && int_size_in_bytes (type) == -1)
     return 1;
@@ -4823,13 +4827,14 @@ return_in_memory_ms_64 (const_tree type,
 {
   HOST_WIDE_INT size = int_size_in_bytes (type);
 
-  /* __m128 and friends are returned in xmm0.  */
-  if (!COMPLEX_MODE_P (mode) && size == 16 && VECTOR_MODE_P (mode))
-    return 0;
+  /* Structures pass always via memory.  */
+  if (mode == BLKmode)
+    return 1;
 
-  /* Otherwise, the size must be exactly in [1248]. But not for complex. */
+  /* Otherwise, the size must be exactly in [1248]. But not for complex
+     and vector. */
   return (size != 1 && size != 2 && size != 4 && size != 8)
-         || COMPLEX_MODE_P (mode);
+         || COMPLEX_MODE_P (mode) || VECTOR_MODE_P (mode);
 }
 
 int
=