sccvn: Fix handling of POINTER_PLUS_EXPR in memset offset [PR93582]
authorJakub Jelinek <jakub@redhat.com>
Thu, 5 Mar 2020 07:00:04 +0000 (08:00 +0100)
committerJakub Jelinek <jakub@redhat.com>
Thu, 5 Mar 2020 07:00:04 +0000 (08:00 +0100)
commitfe19699ae2883b252d30f98481d32dabff00744b
tree156e2e7833a639349d5dd27e30c93c0f60b8ab49
parentcb2409c60aeff498064346f85165531a3bbead14
sccvn: Fix handling of POINTER_PLUS_EXPR in memset offset [PR93582]

> > where POINTER_PLUS_EXPR last operand has sizetype type, thus unsigned,
> > and in the testcase gimple_assign_rhs2 (def) is thus 0xf000000000000001ULL
> > which multiplied by 8 doesn't fit into signed HWI.  If it would be treated
> > as signed offset instead, it would fit (-0xfffffffffffffffLL, multiplied
> > by 8 is -0x7ffffffffffffff8LL).  Unfortunately with the poly_int obfuscation
> > I'm not sure how to convert it from unsigned to signed poly_int.
>
> mem_ref_offset provides a boiler-plate for this:
>
> poly_offset_int::from (wi::to_poly_wide (TREE_OPERAND (t, 1)), SIGNED);

Thanks, that seems to work.
The test now works on both big-endian and little-endian.

2020-03-05  Richard Biener  <rguenther@suse.de>
    Jakub Jelinek  <jakub@redhat.com>

PR tree-optimization/93582
* tree-ssa-sccvn.c (vn_reference_lookup_3): Treat POINTER_PLUS_EXPR
last operand as signed when looking for memset offset.  Formatting
fix.

* gcc.dg/tree-ssa/pr93582-11.c: New test.

Co-authored-by: Richard Biener <rguenther@suse.de>
gcc/ChangeLog
gcc/testsuite/ChangeLog
gcc/testsuite/gcc.dg/tree-ssa/pr93582-11.c [new file with mode: 0644]
gcc/tree-ssa-sccvn.c