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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/113421] wrong code with -O -fno-tree-fre and
 _BitInt() multiplication
Date: Wed, 17 Jan 2024 13:44:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113421

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:9f8ba332e988fb582f6ca32465f6d65283f53b3a

commit r14-8186-g9f8ba332e988fb582f6ca32465f6d65283f53b3a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Jan 17 14:43:40 2024 +0100

    lower-bitint: Avoid overlap between destinations and sources in libgcc
calls [PR113421]

    The following testcase is miscompiled because the bitint lowering emits=
 a
      .MULBITINT (&a, 1024, &a, 1024, &x, 1024);
    call.  The bug is in the overlap between the destination and source, th=
at
is
    something the libgcc routines don't handle, they use the source arrays
    during the entire algorithms which computes the destination array(s).
    For the mapping of SSA_NAMEs to VAR_DECLs the code already supports that
    correctly, but the checking whether a load from memory can be used dire=
ctly
    without a temporary even when earlier we decided to merge the
    multiplication/division/modulo etc. with a store didn't.

    The following patch implements that.

    2024-01-17  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/113421
            * gimple-lower-bitint.cc (stmt_needs_operand_addr): Adjust func=
tion
            comment.
            (bitint_dom_walker::before_dom_children): Add g temporary to
simplify
            formatting.  Start at vop rather than cvop even if stmt is a st=
ore
            and needs_operand_addr.

            * gcc.dg/torture/bitint-50.c: New test.=