[Bug rtl-optimization/112995] sel-sched2 ICE without checking verify_changes

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112995

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kewen Lin <li...@gcc.gnu.org>:

https://gcc.gnu.org/g:5fbc77726f68a35a938c829fe259d6c376d608ca

commit r14-6768-g5fbc77726f68a35a938c829fe259d6c376d608ca
Author: Kewen Lin <li...@linux.ibm.com>
Date:   Wed Dec 20 23:20:19 2023 -0600

    sel-sched: Verify change before replacing dest in EXPR_INSN_RTX [PR112995]

    PR112995 exposed one issue in current try_replace_dest_reg
    that the result rtx insn after replace_dest_with_reg_in_expr
    is probably unable to match any constraints.  Although there
    are some checks on the changes onto dest or src of orig_insn,
    none is performed on the EXPR_INSN_RTX.

    Initially we have:

    (insn 31 6 10 2 (set (reg/v:SI 9 9 [orig:119 c ] [119])
                         (reg/v:SI 64 0 [orig:119 c ] [119]))
                    "test.i":5:5 555 {*movsi_internal1} ... )
    ...
    (insn 25 10 27 2 (set (reg:DI 64 0 [135])
                          (sign_extend:DI
                             (reg/v:SI 9 9 [orig:119 c ] [119])))
                     "test.i":6:5 31 {extendsidi2} ...)

    with moving up, we have:

    (insn 46 0 0 (set (reg:DI 64 0 [135])
                      (sign_extend:DI
                          (reg/v:SI 64 0 [orig:119 c ] [119])))
                       31 {extendsidi2} ...)

    in try_replace_dest_reg, we updated the above EXPR_INSN_RTX to:

    (insn 48 0 0 (set (reg:DI 32 0)
                      (sign_extend:DI
                          (reg/v:SI 64 0 [orig:119 c ] [119])))
                       31 {extendsidi2} ...)

    The dest (reg 64) is a VR (also VSX REG), the updating makes
    it become to (reg 32) which is a FPR (also VSX REG), we have
    an alternative to match "VR,VR" but no one to match "FPR/VSX,
    VR/VSX", so it fails with ICE.

    This patch is to add the check before actually replacing dest
    in expr with reg.

            PR rtl-optimization/112995

    gcc/ChangeLog:

            * sel-sched.cc (try_replace_dest_reg): Check the validity of the
            replaced insn before actually replacing dest in expr.

    gcc/testsuite/ChangeLog:

            * gcc.target/powerpc/pr112995.c: New test.