[Bug target/126434] [17 Regression] ICE: invalid rtl sharing found in the insn {zero_extendsidi2} since r17-1375

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126434

--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Philipp Tomsich <[email protected]>:

https://gcc.gnu.org/g:91663770f795fd02688c1da004337a1e7c94e810

commit r17-2790-g91663770f795fd02688c1da004337a1e7c94e810
Author: Konstantinos Eleftheriou <[email protected]>
Date:   Tue Jul 28 11:27:38 2026 +0200

    avoid-store-forwarding: Unshare load dest when re-applying extension
[PR126434]

    When store forwarding is avoided without eliminating the load (the store
    only partially covers it), the extension wrapping the load's MEM is
    re-applied after the bit-insert sequence, reusing SET_DEST (load) as the
    move destination. As the load insn is kept here, that rtx is now shared
    between two insns. That is fine for a plain REG, but in the case that the
    dest is a SUBREG, it must not be shared (verify_rtx_sharing ICEs).

    Unshare the destination with copy_rtx when building the move.

    Bootstrapped/regtested on AArch64, x86-64 and PowerPC.

            PR rtl-optimization/126434

    gcc/ChangeLog:

            * avoid-store-forwarding.cc (process_store_forwarding): Unshare the
            load destination when building the re-extension move.

    gcc/testsuite/ChangeLog:

            * gcc.dg/pr126434.c: New test.