Re: [PATCH] tree-optimization/111048 - avoid flawed logic in fold_vec_perm

[Richard Sandiford <richard.sandiford@arm.com>]

Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> writes:
> On Mon, 21 Aug 2023 at 12:26, Richard Biener <rguenther@suse.de> wrote:
>>
>> On Sat, 19 Aug 2023, Prathamesh Kulkarni wrote:
>>
>> > On Fri, 18 Aug 2023 at 14:52, Richard Biener <rguenther@suse.de> wrote:
>> > >
>> > > On Fri, 18 Aug 2023, Richard Sandiford wrote:
>> > >
>> > > > Richard Biener <rguenther@suse.de> writes:
>> > > > > The following avoids running into somehow flawed logic in fold_vec_perm
>> > > > > for non-VLA vectors.
>> > > > >
>> > > > > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
>> > > > >
>> > > > > Richard.
>> > > > >
>> > > > >     PR tree-optimization/111048
>> > > > >     * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
>> > > > >     vectors first.
>> > > > >
>> > > > >     * gcc.dg/torture/pr111048.c: New testcase.
>> > > >
>> > > > Please don't do this as a permanent thing.  It was a deliberate choice
>> > > > to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
>> > > > logic gets more coverage.  Like you say, if something is wrong for VLS
>> > > > then the chances are that it's also wrong for VLA.
>> > >
>> > > Sure, feel free to undo this change together with the fix for the
>> > > VLA case.
>> > Hi,
>> > The attached patch reverts the workaround, and fixes the issue.
>> > Bootstrapped+tested on aarch64-linux-gnu with and without SVE, and
>> > x64_64-linux-gnu.
>> > OK to commit ?
>>
>> OK.
> Thanks, committed to trunk in 649388462e9a3c2de0b90ce525de8044704cc521

Thanks for the patch.  Please remember to close the PR too.

Richard