[Bug tree-optimization/104162] [12/13 Regression] Missed CSE after lowering of &MEM[ptr_1 + CST]

cvs-commit at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Thu May 5 12:41:42 GMT 2022


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104162

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:ee1cb43bc76de800efa0ade687b0cd28e62a5f82

commit r13-137-gee1cb43bc76de800efa0ade687b0cd28e62a5f82
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Jan 26 15:34:54 2022 +0100

    tree-optimization/104162 - CSE of &MEM[ptr].a[i] and ptr + CST

    This adds the capability to value-numbering of treating complex
    address expressions where the offset becomes invariant as equal
    to a POINTER_PLUS_EXPR.  This restores CSE that is now prevented
    by early lowering of &MEM[ptr + CST] to a POINTER_PLUS_EXPR.

    Unfortunately this regresses gcc.dg/asan/pr99673.c again, so
    the testcase is adjusted accordingly.

    2022-01-26  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/104162
            * tree-ssa-sccvn.cc (vn_reference_lookup): Handle
            &MEM[_1 + 5].a[i] like a POINTER_PLUS_EXPR if the offset
            becomes invariant.
            (vn_reference_insert): Likewise.

            * gcc.dg/tree-ssa/ssa-fre-99.c: New testcase.
            * gcc.dg/asan/pr99673.c: Adjust.


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