[Bug rtl-optimization/105041] '-fcompare-debug' failure w/ -mcpu=power6 -O2 -fharden-compares -frename-registers

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105041

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Surya Kumari Jangala
<jskumari@gcc.gnu.org>:

https://gcc.gnu.org/g:0380d008b1474373852fd2fc921886491304f854

commit r12-8568-g0380d008b1474373852fd2fc921886491304f854
Author: Surya Kumari Jangala <jskumari@linux.vnet.ibm.com>
Date:   Fri Jun 10 19:52:57 2022 +0530

    regrename: Fix -fcompare-debug issue in check_new_reg_p [PR105041]

    In check_new_reg_p, the nregs of a du chain is computed by obtaining the
    MODE of the first element in the chain, and then calling
    hard_regno_nregs() with the MODE. But the first element of the chain can
    be a DEBUG_INSN whose mode need not be the same as the rest of the
    elements in the du chain. This was resulting in fcompare-debug failure
    as check_new_reg_p was returning a different result with -g for the same
    candidate register. We can instead obtain nregs from the du chain
    itself.

    2022-06-10  Surya Kumari Jangala  <jskumari@linux.ibm.com>

    gcc/
            PR rtl-optimization/105041
            * regrename.cc (check_new_reg_p): Use nregs value from du chain.

    gcc/testsuite/
            PR rtl-optimization/105041
            * gcc.target/powerpc/pr105041.c: New test.

    (cherry picked from commit 3e16b4359e86b36676ed01219e6deafa95f3c16b)