[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 #5 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
(In reply to Roger Sayle from comment #4)
> Created attachment 65243 [details]
> 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.

It hits ICE for below testcase with -O2 -mno-sse2

typedef float v4sf __attribute__((vector_size(16)));
v4sf fab00 (float a, float b) { return (v4sf){a,b,0,0}; }