[Bug rtl-optimization/125173] ICE: in combine_and_move_insns, at ira.cc:3992 with -O1 -fno-fuse-ops-with-volatile-access -fno-forward-propagate --param=max-cse-insns=0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125173

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Stefan Schulze Frielinghaus
<stefansf@gcc.gnu.org>:

https://gcc.gnu.org/g:107d2ad166d09883b43ec1a5cf1e37c68b134a93

commit r17-1508-g107d2ad166d09883b43ec1a5cf1e37c68b134a93
Author: Stefan Schulze Frielinghaus <stefansf@gcc.gnu.org>
Date:   Fri Jun 12 11:15:14 2026 +0200

    ira: Allow multiple uses within an insn [PR125173]

    For the attached test we end up during IRA with

    6: r99:DI=`s'
      REG_EQUIV `s'
    7: {[`b']=asm_operands;
        [const(`s'+0x4)]=asm_operands;
        [`a']=asm_operands;clobber flags:CC;}
      REG_DEAD r99:DI
      REG_UNUSED flags:CC

    where r99 is used in each asm_operands

    (mem/c:SI (plus:DI (reg/f:DI 99)
                       (const_int 4 [0x4])) [2 s.d+0 S4 A32])

    This in turn means that we hit multiple times the very same insn while
    iterating over all uses of r99 which in the end triggers the assert.

    This patch relaxes the assert since what we want to ensure here is that
    a register is not used by multiple insns since otherwise we cannot
    trivially move or delete the definition.

            PR rtl-optimization/125173

    gcc/ChangeLog:

            * ira.cc (combine_and_move_insns): Allow multiple uses within
            an insn.

    gcc/testsuite/ChangeLog:

            * gcc.dg/pr125173-1.c: New test.