[PATCH] Fix PR56118

Alan Lawrence alan.lawrence@arm.com
Fri Nov 13 18:05:00 GMT 2015

On 10/11/15 09:34, Richard Biener wrote:
> The following fixes PR56118 by adjusting the cost model handling of
> basic-block vectorization to favor the vectorized version in case
> estimated cost is the same as the estimated cost of the scalar
> version.  This makes sense because we over-estimate the vectorized
> cost in several places.
> Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
> Richard.
> 2015-11-10  Richard Biener  <rguenther@suse.de>
> 	PR tree-optimization/56118
> 	* tree-vect-slp.c (vect_bb_vectorization_profitable_p): Make equal
> 	cost favor vectorized version.
> 	* gcc.target/i386/pr56118.c: New testcase.

On AArch64 and ARM targets, this causes PASS->FAIL of

gcc.dg/vect/bb-slp-32.c scan-tree-dump slp2 "vectorization is not profitable"
gcc.dg/vect/bb-slp-32.c -flto -ffat-lto-objects scan-tree-dump slp2 
"vectorization is not profitable"

....that sounds like a good thing ;), so I imagine the xfail directive may just 
need updating. The test also looks to be failing on powerpc64 (according to 

Regards, Alan

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