Re: [PATCH] ipa: Avoid invalid gimple when IPA-CP and IPA-SRA disagree on types (108384)

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Feb 3, 2023 at 10:40 AM Martin Jambor <mjambor@suse.cz> wrote:
>
> On Fri, Feb 03 2023, Richard Biener wrote:
> > On Thu, Feb 2, 2023 at 5:20 PM Martin Jambor <mjambor@suse.cz> wrote:
> >>
> >> Hi,
> >>
> >> when the compiled program contains type mismatches between callers and
> >> callees when it comes to a parameter, IPA-CP can try to propagate one
> >> constant from callers while IPA-SRA may try to split a parameter
> >> expecting a value of a different size on the same offset.  This then
> >> currently leads to creation of a VIEW_CONVERT_EXPR with mismatching
> >> type sizes of LHS and RHS which is correctly flagged by the GIMPLE
> >> verifier as invalid.
> >>
> >> It seems that the best course of action is to try and avoid the
> >> situation altogether and so this patch adds a check to IPA-SRA that
> >> peeks into the result of IPA-CP and when it sees a value on the same
> >> offset but with a mismatching size, it just decides to leave that
> >> particular parameter be.
> >>
> >> Bootstrapped and tested on x86_64-linux, OK for master?
> >
> > OK.  I suppose there are guards elsewhere that never lets a
> > non-UHWI size type (like variable size or poly-int-size) through
> > any of the SRA or CP lattices?
>
> SRA tracks its accesses in simple integers so yes for that part.
>
> As far IPA-CP is concerned... all the values tracked conform to
> is_gimple_ip_invariant, so are either ADDR_EXPRs of a global variable or
> is_gimple_constant's.  So its size should never be variable and I hope
> also never a complex poly-int.  If you think it would be better, I can
> of course add the check.

I think it's OK as-is given this explanation.

Richard.

> Thanks,
>
> Martin
>
>
> >> gcc/ChangeLog:
> >>
> >> 2023-02-02  Martin Jambor  <mjambor@suse.cz>
> >>
> >>         PR ipa/108384
> >>         * ipa-sra.cc (push_param_adjustments_for_index): Remove a size check
> >>         when comparing to an IPA-CP value.
> >>         (dump_list_of_param_indices): New function.
> >>         (adjust_parameter_descriptions): Check for mismatching IPA-CP values.
> >>         Dump removed candidates using dump_list_of_param_indices.
> >>         * ipa-param-manipulation.cc
> >>         (ipa_param_body_adjustments::modify_expression): Add assert checking
> >>         sizes of a VIEW_CONVERT_EXPR will match.
> >>         (ipa_param_body_adjustments::modify_assignment): Likewise.
> >>
> >> gcc/testsuite/ChangeLog:
> >>
> >> 2023-02-02  Martin Jambor  <mjambor@suse.cz>
> >>
> >>         PR ipa/108384
> >>         * gcc.dg/ipa/pr108384.c: New test.
> >> ---