+match them. For example, this should turn into a horizontal add:
+
+typedef float __attribute__((vector_size(16))) v4f32;
+float f32(v4f32 A) {
+ return A[0]+A[1]+A[2]+A[3];
+}
+
+Instead we get this:
+
+_f32: ## @f32
+ pshufd $1, %xmm0, %xmm1 ## xmm1 = xmm0[1,0,0,0]
+ addss %xmm0, %xmm1
+ pshufd $3, %xmm0, %xmm2 ## xmm2 = xmm0[3,0,0,0]
+ movhlps %xmm0, %xmm0 ## xmm0 = xmm0[1,1]
+ movaps %xmm0, %xmm3
+ addss %xmm1, %xmm3
+ movdqa %xmm2, %xmm0
+ addss %xmm3, %xmm0
+ ret
+
+Also, there are cases where some simple local SLP would improve codegen a bit.
+compiling this: