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_type.
* ipa-prop.h (ipa_pass_through_data): New flag refdesc_decremented.
(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 for
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 parameter of
find_reference.
(update_jump_functions_after_inlining): Zap refdesc of new jfunc 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_type, use
it in searching.
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