[Bug target/126619] [17 Regression] Slowdown of s116 from TSVC on x86_64 since r17-2876-gf0bd50e8317926

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126619

--- Comment #4 from Roger Sayle <roger at nextmovesoftware dot com> ---
Created attachment 65243
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65243&action=edit
proposed patch

Hi Hongtao,
Here's my patch to dramatically improve the code generated for V4SF vector
initialization, which also happens to do exactly as you propose, i.e. fall back
to ix86_expand_vector_init_concat in the general case.  This has survived
bootstrap and is currently regression testing (which will identify the
testcases that need to be updated, in addition to spotting any problems).

Please let me know if you have any feedback before I officially post the full
patch to gcc-patches for review.  Sorry for any inconvenience.