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Subject: [Bug ipa/109318] [12/13 Regression] csmith: -fipa-cp seems to cause
 trouble since r12-2523-g13586172d0b70c
Date: Mon, 17 Apr 2023 11:06:20 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109318

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Martin Jambor <jamborm@gcc.gnu.org>:

https://gcc.gnu.org/g:8e08c7886eed5824bebd0e011526ec302d622844

commit r13-7206-g8e08c7886eed5824bebd0e011526ec302d622844
Author: Martin Jambor <mjambor@suse.cz>
Date:   Mon Apr 17 12:59:51 2023 +0200

    ipa: Fix double reference-count decrements for the same edge (PR 107769=
, PR
109318)

    It turns out that since addition of the code that can identify globals
    which are only read from, the code that keeps track of the references
    can decrement their count for the same calls, once during IPA-CP and
    then again during inlining.  Fixed by adding a special flag to the
    pass-through variant and simply wiping out the reference to the
    refdesc structure from the constant ones.

    Moreover, during debugging of the issue I have discovered that the
    code removing references could remove a reference associated with the
    same statement but of a wrong type.  In all cases it wanted to remove
    an IPA_REF_ADDR reference so removing a lesser one instead should do
    no harm in practice, but we should try to be consistent and so this
    patch extends symtab_node::find_reference so that it searches for a
    reference of a given type only.

    gcc/ChangeLog:

    2023-04-14  Martin Jambor  <mjambor@suse.cz>

            PR ipa/107769
            PR ipa/109318
            * cgraph.h (symtab_node::find_reference): Add parameter use_typ=
e.
            * ipa-prop.h (ipa_pass_through_data): New flag refdesc_decremen=
ted.
            (ipa_zap_jf_refdesc): New function.
            (ipa_get_jf_pass_through_refdesc_decremented): Likewise.
            (ipa_set_jf_pass_through_refdesc_decremented): Likewise.
            * ipa-cp.cc (ipcp_discover_new_direct_edges): Provide a value f=
or
            the new parameter of find_reference.
            (adjust_references_in_caller): Likewise. Make sure the constant
jump
            function is not used to decrement a refdec counter again.  Only
            decrement refdesc counters when the pass_through jump function
allows
            it.  Added a detailed dump when decrementing refdesc counters.
            * ipa-prop.cc (ipa_print_node_jump_functions_for_edge): Dump new
flag.
            (ipa_set_jf_simple_pass_through): Initialize the new flag.
            (ipa_set_jf_unary_pass_through): Likewise.
            (ipa_set_jf_arith_pass_through): Likewise.
            (remove_described_reference): Provide a value for the new param=
eter
of
            find_reference.
            (update_jump_functions_after_inlining): Zap refdesc of new jfun=
c if
            the previous pass_through had a flag mandating that we do so.
            (propagate_controlled_uses): Likewise.  Only decrement refdesc
            counters when the pass_through jump function allows it.
            (ipa_edge_args_sum_t::duplicate): Provide a value for the new
            parameter of find_reference.
            (ipa_write_jump_function): Assert the new flag does not have to=
 be
            streamed.
            * symtab.cc (symtab_node::find_reference): Add parameter use_ty=
pe,
use
            it in searching.

    gcc/testsuite/ChangeLog:

    2023-04-06  Martin Jambor  <mjambor@suse.cz>

            PR ipa/107769
            PR ipa/109318
            * gcc.dg/ipa/pr109318.c: New test.
            * gcc.dg/lto/pr107769_0.c: Likewise.=