https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86735
--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index fc3d6f0aebc..a8709972e9c 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -40402,6 +40402,10 @@ ix86_multiplication_cost (const struct processor_costs
*cost,
? cost->mulsd : cost->mulss, true);
else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
{
+ /* vpmullq is used in this case. No emulation is needed. */
+ if (TARGET_AVX512DQ)
+ return ix86_vec_cost (mode, cost->mulss, true);
+
/* V*QImode is emulated with 7-13 insns. */
if (mode == V16QImode || mode == V32QImode)
{
triggered gather coedgen, which may lead to a latent bug.
