Re: [PATCH] Fix powerpc* ICE with vec builtins with -mno-altivec (PR target/82848)

[Segher Boessenkool <segher@kernel.crashing.org>]

Hi Jakub,

On Thu, Nov 23, 2017 at 10:02:24PM +0100, Jakub Jelinek wrote:
> With -mno-altivec -mno-vsx -mno-fold-gimple we error on __builtin_vec*
> builtins used when corresponding ISA is not enabled.
> When folding gimple, in some cases we get away with it (e.g. when folding
> the builtin to PLUS_EXPR on the generic vectors), because
> tree-vect-generic.c lowers those into scalar piecewise operations,
> but e.g. in case of FMA_EXPR tree-vect-generic.c isn't doing anything,
> expects that FMA_EXPR is actually used only if supported, I think similarly
> for various vector widening operations etc.
> 
> One option is not to fold into gimple only those builtins where we know it
> will not work on generic vectors; my preference is to not fold any builtin
> which would be rejected at expansion time, so user get at least consistent
> diagnostics.  Usually people are using the altivec.h etc. headers that error
> if the ISA is not enabled, so this will only affect people that use the
> builtins directly.

Yeah I agree.

Okay for trunk, thanks!


Segher


> 2017-11-23  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/82848
> 	* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Don't fold
> 	builtins not enabled in the currently selected ISA.

(You forgot changelog for the added testcase).