[Bug tree-optimization/103596] [9/10/11 Regression] ICE: tree check: expected class 'type', have 'exceptional' (error_mark) in useless_type_conversion_p, at gimple-expr.c:88 since r8-565-g7581ce9a1ad6df9c

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103596

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Richard Biener
<rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:08f594465fa9b6a4ea1e3816cfecf256e883ff53

commit r11-9524-g08f594465fa9b6a4ea1e3816cfecf256e883ff53
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Dec 7 11:13:39 2021 +0100

    tree-optimization/103596 - fix missed propagation into switches

    may_propagate_copy unnecessarily restricts propagating non-abnormals
    into places that currently contain an abnormal SSA name but are
    not the PHI argument for an abnormal edge.  This causes VN to
    not elide a CFG path that it assumes is elided, resulting in
    released SSA names in the IL.

    The fix is to enhance the may_propagate_copy API to specify the
    destination is _not_ a PHI argument.  I chose to not update only
    the relevant caller in VN and the may_propagate_copy_into_stmt API
    at this point because this is a regression and needs backporting.

    2021-12-07  Richard Biener  <rguenther@suse.de>

            PR tree-optimization/103596
            * tree-ssa-sccvn.c (eliminate_dom_walker::eliminate_stmt):
            Note we are not propagating into a PHI argument to
may_propagate_copy.
            * tree-ssa-propagate.h (may_propagate_copy): Add
            argument specifying whether we propagate into a PHI arg.
            * tree-ssa-propagate.c (may_propagate_copy): Likewise.
            When not doing so we can replace an abnormal with
            something else.
            (may_propagate_into_stmt): Update may_propagate_copy calls.
            (replace_exp_1): Move propagation checking code to
            propagate_value and rename to ...
            (replace_exp): ... this and elide previous wrapper.
            (propagate_value): Perform checking with adjusted
            may_propagate_copy call and dispatch to replace_exp.

            * gcc.dg/torture/pr103596.c: New testcase.

    (cherry picked from commit 6e8a31275fda445fb3e8d98e53f5e1541f4727af)