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Subject: [Bug rtl-optimization/104198] [12 regression] ifcvt change breaks
 64-bit SPARC bootstrap
Date: Tue, 08 Feb 2022 19:49:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104198

--- Comment #16 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Robin Dapp <rdapp@gcc.gnu.org>:

https://gcc.gnu.org/g:d0d4601ccde3c4849f6e7244035f1a899d608cb7

commit r12-7114-gd0d4601ccde3c4849f6e7244035f1a899d608cb7
Author: Robin Dapp <rdapp@linux.ibm.com>
Date:   Tue Feb 8 16:11:20 2022 +0100

    ifcvt: Fix PR104153 and PR104198.

    This is a bugfix for r12-6747-gaa8cfe785953a0 which caused an ICE
    on or1k (PR104153) and broke SPARC bootstrap (PR104198).

    cond_exec_get_condition () returns the jump condition directly and we
    now pass it to the backend.  The or1k backend modified the condition
    in-place (other backends do that as well) but this modification is not
    reverted when the sequence in question is discarded.  Therefore we copy
    the RTX instead of using it directly.

    The SPARC problem is due to the SPARC backend recreating the initial
    condition when being passed a CC comparison.  This causes the sequence
    to read from an already overwritten condition operand.  Generally, this
    could also happen on other targets.  The workaround is to always first
    emit to a temporary.  In a second run of noce_convert_multiple_sets_1
    we know which sequences actually require the comparison and will use no
    temporaries if all sequences after the current one do not require it.

            PR rtl-optimization/104198
            PR rtl-optimization/104153

    gcc/ChangeLog:

            * ifcvt.cc (noce_convert_multiple_sets_1): Copy rtx instead of
            using it directly.  Rework comparison handling and always
            perform a second pass.

    gcc/testsuite/ChangeLog:

            * gcc.dg/pr104198.c: New test.=