[Bug rtl-optimization/105231] [12 Regression] ICE: in rtl_verify_bb_insns, at cfgrtl.cc:2797 (flow control insn inside a basic block) with custom flags since r12-4767-g81342e95827f77c0

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105231

--- Comment #30 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:4f77738c3b44cb6b7bfe2a7ef823a5d9d75c0e79

commit r12-8239-g4f77738c3b44cb6b7bfe2a7ef823a5d9d75c0e79
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Apr 14 14:06:22 2022 +0200

    rtl-optimization/105231 - distribute_notes and REG_EH_REGION

    The following mitigates a problem in combine distribute_notes which
    places an original REG_EH_REGION based on only may_trap_p which is
    good to test whether a non-call insn can possibly throw but not if
    actually it does or we care.  That's something we decided at RTL
    expansion time where we possibly still know the insn evaluates
    to a constant.

    In fact, the REG_EH_REGION note with lp > 0 can only come from the
    original i3 and an assert is added to that effect.  That means we only
    need to retain the note on i3 or, if that cannot trap, drop it but we
    should never move it to i2.

    The following places constraints on the insns to combine with
    non-call exceptions since we cannot handle the case where we
    have more than one EH side-effect in the IL.  The patch also
    makes sure we can accumulate that on i3 and do not split
    a possible exception raising part of it to i2.  As a special
    case we do not place any restriction on all externally
    throwing insns when there is no REG_EH_REGION present.

    2022-04-22  Richard Biener  <rguenther@suse.de>

            PR rtl-optimization/105231
            * combine.cc (distribute_notes): Assert that a REG_EH_REGION
            with landing pad > 0 is from i3.  Put any REG_EH_REGION note
            on i3 or drop it if the insn can not trap.
            (try_combine): Ensure that we can merge REG_EH_REGION notes
            with non-call exceptions.  Ensure we are not splitting a
            trapping part of an insn with non-call exceptions when there
            is any REG_EH_REGION note to preserve.

            * gcc.dg/torture/pr105231.c: New testcase.