[Bug target/115069] [14/15 regression] 8 bit integer vector performance regression, x86, between gcc-14 and gcc-13 using avx2 target clones on skylake platform

[ubizjak at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115069

Uroš Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-05-17

--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
A better patch:

--cut here--
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 4e16aedc5c1..88bfc43201b 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -24493,6 +24493,10 @@ ix86_expand_vecop_qihi2 (enum rtx_code code, rtx dest,
rtx op1, rtx op2)
   bool op2vec = GET_MODE_CLASS (GET_MODE (op2)) == MODE_VECTOR_INT;
   bool uns_p = code != ASHIFTRT;

+  /* ??? VPERMQ is slow and VPMOWVB is only available under AVX512BW.  */
+  if (!TARGET_AVX512BW)
+    return false;
+
   if ((qimode == V16QImode && !TARGET_AVX2)
       || (qimode == V32QImode && (!TARGET_AVX512BW || !TARGET_EVEX512))
       /* There are no V64HImode instructions.  */
--cut here--