Re: [PATCH] Fix out-of-ssa with unsupported vector types (PR rtl-optimization/90756)

[Jeff Law <law@redhat.com>]

On 7/3/19 1:59 AM, Jakub Jelinek wrote:
> Hi!
> 
> This weird hink has been added by Alex in r228175, it isn't clear why
> nor how it ever can be correct.  While say for DECL_MODE we have the problem
> that for global vars when switching between functions with different ISA
> selections the mode might not be ok, TYPE_MODE is stored as a raw vector
> mode that a function overrides to BLKmode if that particular vector mode is
> not supported.  This hunk breaks that assumption and leaks unsupported
> vector modes in the IL of the functions which then have no way to handle
> that, but even before that happens usually it breaks because we try to
> convert_mode between BLKmode and the unsupported vector mode or vice versa
> on PHI nodes.
> 
> Alex, do you remember why this has been done?
> 
> Patch has been bootstrapped/regtested on x86_64-linux and i686-linux (the
> latter didn't have SSE enabled by default), Jeff said he'll test it on many
> crosses.  Ok for trunk if that testing succeeds?
> 
> 2019-07-03  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR rtl-optimization/90756
> 	* explow.c (promote_ssa_mode): Always use TYPE_MODE, don't bypass it
> 	for VECTOR_TYPE_P.
> 
> 	* gcc.dg/pr90756.c: New test.
Nothing tripped related to this patch in the various targets in my tester.

jeff