From b89e4559950c79d8933013305c19d7014a39cdb1 Mon Sep 17 00:00:00 2001 From: Jan Hubicka Date: Sat, 26 Sep 2020 08:12:44 +0200 Subject: Track arguments pointing to local or readonly memory in ipa-fnsummary this patch implement tracking wehther argument points to readonly memory. This is is useful for ipa-modref as well as for inline heuristics. It is desirable to inline functions that dereference pointers to local variables in order to support SRA. We always did the oposite heuristics (guessing that the dereferences will be optimized out with 50% probability) but here we could increase the probability for cases where we can track that argument is indeed a local memory (or readonly which is also good) * ipa-fnsummary.c (dump_ipa_call_summary): Dump points_to_local_or_readonly_memory flag. (analyze_function_body): Compute points_to_local_or_readonly_memory flag. (remap_edge_change_prob): Rename to ... (remap_edge_params): ... this one; update points_to_local_or_readonly_memory. (remap_edge_summaries): Update. (read_ipa_call_summary): Stream the new flag. (write_ipa_call_summary): Likewise. * ipa-predicate.h (struct inline_param_summary): Add points_to_local_or_readonly_memory. (inline_param_summary::equal_to): Update. (inline_param_summary::useless_p): Update. --- gcc/ipa-fnsummary.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) (limited to 'gcc/ipa-fnsummary.c') diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c index cbcf0c4..4c1c1f9 100644 --- a/gcc/ipa-fnsummary.c +++ b/gcc/ipa-fnsummary.c @@ -980,6 +980,9 @@ dump_ipa_call_summary (FILE *f, int indent, struct cgraph_node *node, else if (prob != REG_BR_PROB_BASE) fprintf (f, "%*s op%i change %f%% of time\n", indent + 2, "", i, prob * 100.0 / REG_BR_PROB_BASE); + if (es->param[i].points_to_local_or_readonly_memory) + fprintf (f, "%*s op%i points to local or readonly memory\n", + indent + 2, "", i); } if (!edge->inline_failed) { @@ -2671,6 +2674,9 @@ analyze_function_body (struct cgraph_node *node, bool early) int prob = param_change_prob (&fbi, stmt, i); gcc_assert (prob >= 0 && prob <= REG_BR_PROB_BASE); es->param[i].change_prob = prob; + es->param[i].points_to_local_or_readonly_memory + = points_to_local_or_readonly_memory_p + (gimple_call_arg (stmt, i)); } } @@ -3781,15 +3787,17 @@ inline_update_callee_summaries (struct cgraph_node *node, int depth) ipa_call_summaries->get (e)->loop_depth += depth; } -/* Update change_prob of EDGE after INLINED_EDGE has been inlined. +/* Update change_prob and points_to_local_or_readonly_memory of EDGE after + INLINED_EDGE has been inlined. + When function A is inlined in B and A calls C with parameter that changes with probability PROB1 and C is known to be passthrough of argument if B that change with probability PROB2, the probability of change is now PROB1*PROB2. */ static void -remap_edge_change_prob (struct cgraph_edge *inlined_edge, - struct cgraph_edge *edge) +remap_edge_params (struct cgraph_edge *inlined_edge, + struct cgraph_edge *edge) { if (ipa_node_params_sum) { @@ -3823,7 +3831,16 @@ remap_edge_change_prob (struct cgraph_edge *inlined_edge, prob = 1; es->param[i].change_prob = prob; + + if (inlined_es + ->param[id].points_to_local_or_readonly_memory) + es->param[i].points_to_local_or_readonly_memory = true; } + if (!es->param[i].points_to_local_or_readonly_memory + && jfunc->type == IPA_JF_CONST + && points_to_local_or_readonly_memory_p + (ipa_get_jf_constant (jfunc))) + es->param[i].points_to_local_or_readonly_memory = true; } } } @@ -3856,7 +3873,7 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge, if (e->inline_failed) { class ipa_call_summary *es = ipa_call_summaries->get (e); - remap_edge_change_prob (inlined_edge, e); + remap_edge_params (inlined_edge, e); if (es->predicate) { @@ -3882,7 +3899,7 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge, predicate p; next = e->next_callee; - remap_edge_change_prob (inlined_edge, e); + remap_edge_params (inlined_edge, e); if (es->predicate) { p = es->predicate->remap_after_inlining @@ -4208,12 +4225,19 @@ read_ipa_call_summary (class lto_input_block *ib, struct cgraph_edge *e, { es->param.safe_grow_cleared (length, true); for (i = 0; i < length; i++) - es->param[i].change_prob = streamer_read_uhwi (ib); + { + es->param[i].change_prob = streamer_read_uhwi (ib); + es->param[i].points_to_local_or_readonly_memory + = streamer_read_uhwi (ib); + } } else { for (i = 0; i < length; i++) - streamer_read_uhwi (ib); + { + streamer_read_uhwi (ib); + streamer_read_uhwi (ib); + } } } @@ -4438,7 +4462,10 @@ write_ipa_call_summary (struct output_block *ob, struct cgraph_edge *e) streamer_write_uhwi (ob, 0); streamer_write_uhwi (ob, es->param.length ()); for (i = 0; i < (int) es->param.length (); i++) - streamer_write_uhwi (ob, es->param[i].change_prob); + { + streamer_write_uhwi (ob, es->param[i].change_prob); + streamer_write_uhwi (ob, es->param[i].points_to_local_or_readonly_memory); + } } -- cgit v1.1