From c4a92a9117a034e7cf291ae51d8b9b844fb5a88b Mon Sep 17 00:00:00 2001 From: Martin Jambor Date: Tue, 22 Nov 2022 18:22:03 +0100 Subject: [PATCH] ipa-cp: Do not be too optimistic about self-recursive edges (PR 107661) PR 107661 shows that function push_agg_values_for_index_from_edge should not attempt to optimize self-recursive call graph edges when called from cgraph_edge_brings_all_agg_vals_for_node. Unlike when being called from find_aggregate_values_for_callers_subset, we cannot expect that any cloning for constants would lead to the edge leading from a new clone to the same new clone, in this case it would only be redirected to a new callee. Fixed by adding a parameter to push_agg_values_from_edge whether being optimistic about self-recursive edges is possible. gcc/ChangeLog: 2022-11-22 Martin Jambor PR ipa/107661 * ipa-cp.cc (push_agg_values_from_edge): New parameter optimize_self_recursion, use it to decide whether to pass interim to the helper function. (find_aggregate_values_for_callers_subset): Pass true in the new parameter of push_agg_values_from_edge. (cgraph_edge_brings_all_agg_vals_for_node): Pass false in the new parameter of push_agg_values_from_edge. gcc/testsuite/ChangeLog: 2022-11-22 Martin Jambor PR ipa/107661 * g++.dg/ipa/pr107661.C: New test. --- gcc/ipa-cp.cc | 18 +++++++++------ gcc/testsuite/g++.dg/ipa/pr107661.C | 45 +++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/g++.dg/ipa/pr107661.C diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc index d2bcd5e..f0feb4b 100644 --- a/gcc/ipa-cp.cc +++ b/gcc/ipa-cp.cc @@ -5752,14 +5752,16 @@ push_agg_values_for_index_from_edge (struct cgraph_edge *cs, int index, description of ultimate callee of CS or the one it was cloned from (the summary where lattices are). If INTERIM is non-NULL, it contains the current interim state of collected aggregate values which can be used to - compute values passed over self-recursive edges and to skip values which - clearly will not be part of intersection with INTERIM. */ + compute values passed over self-recursive edges (if OPTIMIZE_SELF_RECURSION + is true) and to skip values which clearly will not be part of intersection + with INTERIM. */ static void push_agg_values_from_edge (struct cgraph_edge *cs, ipa_node_params *dest_info, vec *res, - const ipa_argagg_value_list *interim) + const ipa_argagg_value_list *interim, + bool optimize_self_recursion) { ipa_edge_args *args = ipa_edge_args_sum->get (cs); if (!args) @@ -5785,7 +5787,9 @@ push_agg_values_from_edge (struct cgraph_edge *cs, ipcp_param_lattices *plats = ipa_get_parm_lattices (dest_info, index); if (plats->aggs_bottom) continue; - push_agg_values_for_index_from_edge (cs, index, res, interim); + push_agg_values_for_index_from_edge (cs, index, res, + optimize_self_recursion ? interim + : NULL); } } @@ -5804,7 +5808,7 @@ find_aggregate_values_for_callers_subset (struct cgraph_node *node, /* gather_edges_for_value puts a non-recursive call into the first element of callers if it can. */ auto_vec interim; - push_agg_values_from_edge (callers[0], dest_info, &interim, NULL); + push_agg_values_from_edge (callers[0], dest_info, &interim, NULL, true); unsigned valid_entries = interim.length (); if (!valid_entries) @@ -5815,7 +5819,7 @@ find_aggregate_values_for_callers_subset (struct cgraph_node *node, { auto_vec last; ipa_argagg_value_list avs (&interim); - push_agg_values_from_edge (callers[i], dest_info, &last, &avs); + push_agg_values_from_edge (callers[i], dest_info, &last, &avs, true); valid_entries = intersect_argaggs_with (interim, last); if (!valid_entries) @@ -5882,7 +5886,7 @@ cgraph_edge_brings_all_agg_vals_for_node (struct cgraph_edge *cs, ipa_node_params *dest_info = ipa_node_params_sum->get (node); gcc_checking_assert (dest_info->ipcp_orig_node); dest_info = ipa_node_params_sum->get (dest_info->ipcp_orig_node); - push_agg_values_from_edge (cs, dest_info, &edge_values, &existing); + push_agg_values_from_edge (cs, dest_info, &edge_values, &existing, false); const ipa_argagg_value_list avl (&edge_values); return avl.superset_of_p (existing); } diff --git a/gcc/testsuite/g++.dg/ipa/pr107661.C b/gcc/testsuite/g++.dg/ipa/pr107661.C new file mode 100644 index 0000000..cc6f853 --- /dev/null +++ b/gcc/testsuite/g++.dg/ipa/pr107661.C @@ -0,0 +1,45 @@ +/* { dg-do run { target c++11 } } */ +/* { dg-options "-O1 -fipa-cp -fipa-cp-clone" } */ + +struct R {} RGood; +struct L {} LBad; + +volatile int vi; +static void __attribute__((noipa)) L_run(void) { vi = 0; __builtin_abort (); } +static void callback_fn_L(void) { vi = 1; L_run(); } +static void callback_fn_R(void) { vi = 2; } + +struct function_ref { + void (*callback)(void) = nullptr; + + function_ref(L * pl) { callback = callback_fn_L; } + function_ref(R * pr) { callback = callback_fn_R; } +}; + +// allow one level of recursion to call callback twice +static int is_recur(void) { + static int n = 0; + switch (n++) { + case 0: return 1; + default: return 0; + } +} + +static void do3(volatile int * punused, function_ref Expired) { + Expired.callback(); + + if (is_recur()) + do3(punused, Expired); +} + +static void do1(function_ref Expired) { + volatile int unused = 42; + + do3(&unused, Expired); +} + +int main(int, const char **) { do1(&RGood); return 0; } + +void seemingly_unused_foo(void) { do1(&LBad); } + +void (*fnptr)(void) = seemingly_unused_foo; -- 2.7.4