x86/AVX512: use VMOVDDUP for broadcast to V2DF

Like is already the case for the AVX/AVX2 form, VMOVDDUP - acting on
double precision floating values - is more appropriate to use here, and
it can also result in shorter insn encodings when source is memory or
%xmm0...%xmm7, and no masking is applied (in allowing a 2-byte VEX
prefix then instead of a 3-byte one).

gcc/

	* config/i386/sse.md (<avx512>_vec_dup<mode><mask_name>): Use
	vmovddup.

diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index a0824ef2350cac986db4b826ac6d13499dcc7162..70d7410f7a916678c4edb8e084028db7c6cfb5d7 100644 (file)
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -25922,9 +25922,9 @@
   "TARGET_AVX512F"
 {
   /*  There is no DF broadcast (in AVX-512*) to 128b register.
-      Mimic it with integer variant.  */
+      Mimic it with vmovddup, just like vec_dupv2df<mask_name> does.  */
   if (<MODE>mode == V2DFmode)
-    return "vpbroadcastq\t{%1, %0<mask_operand2>|%0<mask_operand2>, %q1}";
+    return "vmovddup\t{%1, %0<mask_operand2>|%0<mask_operand2>, %q1}";
 
   return "v<sseintprefix>broadcast<bcstscalarsuff>\t{%1, %0<mask_operand2>|%0<mask_operand2>, %<iptr>1}";
 }