https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93318
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jan Hubicka <hubi...@gcc.gnu.org>: https://gcc.gnu.org/g:40d240315a6e5ff2010769bfa1c19264217b5f1c commit r10-6301-g40d240315a6e5ff2010769bfa1c19264217b5f1c Author: Jan Hubicka <j...@suse.cz> Date: Tue Jan 28 21:30:14 2020 +0100 ipa: fix handling of multiple speculations (PR93318) This patch started as work to resole Richard's comment on quadratic lookups in resolve_speculation. While doing it I however noticed multiple problems in the new speuclative call code which made the patch quite big. In particular: 1) Before applying speculation we consider only targets with at lest probability 1/2. If profile is sane at most two targets can have probability greater or equal to 1/2. So the new multi-target speculation code got enabled only in very special scenario when there ae precisely two target with precise probability 1/2 (which is tested by the single testcase). As a conseuqence the multiple target logic got minimal test coverage and this made us to miss several ICEs. 2) Profile updating in profile merging, tree-inline and indirect call expansion was wrong which led to inconsistent profiles (as already seen on the testcase). 3) Code responsible to turn speculative call to direct call was broken for anything with more than one target. 4) There were multiple cases where call_site_hash went out of sync which eventually leads to an ICE.. 5) Some code expects that all speculative call targets forms a sequence in the callee linked list but there is no code to maintain that invariant nor a verifier. Fixing this it became obvious that the current API of speculative_call_info is not useful because it really builds on fact tht there are precisely three components (direct call, ref and indirect call) in every speculative call sequence. I ended up replacing it with iterator API for direct call (first_speculative_call_target, next_speculative_call_target) and accessors for the other coponents updating comment in cgraph.h. Finally I made the work with call site hash more effetive by updating edge manipulation to keep them in sequence. So first one can be looked up from the hash and then they can be iterated by callee. There are other things that can be improved (for example the speculation should start with most common target first), but I will try to keep that for next stage1. This patch is mostly about getting rid of ICE and profile corruption which is a regression from GCC 9. Honza gcc/ChangeLog: 2020-01-28 Jan Hubicka <hubi...@ucw.cz> PR lto/93318 * cgraph.c (cgraph_add_edge_to_call_site_hash): Update call site hash only when edge is first within the sequence. (cgraph_edge::set_call_stmt): Update handling of speculative calls. (symbol_table::create_edge): Do not set target_prob. (cgraph_edge::remove_caller): Watch for speculative calls when updating the call site hash. (cgraph_edge::make_speculative): Drop target_prob parameter. (cgraph_edge::speculative_call_info): Remove. (cgraph_edge::first_speculative_call_target): New member function. (update_call_stmt_hash_for_removing_direct_edge): New function. (cgraph_edge::resolve_speculation): Rewrite to new API. (cgraph_edge::speculative_call_for_target): New member function. (cgraph_edge::make_direct): Rewrite to new API; fix handling of multiple speculation targets. (cgraph_edge::redirect_call_stmt_to_callee): Likewise; fix updating of profile. (verify_speculative_call): Verify that targets form an interval. * cgraph.h (cgraph_edge::speculative_call_info): Remove. (cgraph_edge::first_speculative_call_target): New member function. (cgraph_edge::next_speculative_call_target): New member function. (cgraph_edge::speculative_call_target_ref): New member function. (cgraph_edge;:speculative_call_indirect_edge): New member funtion. (cgraph_edge): Remove target_prob. * cgraphclones.c (cgraph_node::set_call_stmt_including_clones): Fix handling of speculative calls. * ipa-devirt.c (ipa_devirt): Fix handling of speculative cals. * ipa-fnsummary.c (analyze_function_body): Likewise. * ipa-inline.c (speculation_useful_p): Use new speculative call API. * ipa-profile.c (dump_histogram): Fix formating. (ipa_profile_generate_summary): Watch for overflows. (ipa_profile): Do not require probablity to be 1/2; update to new API. * ipa-prop.c (ipa_make_edge_direct_to_target): Update to new API. (update_indirect_edges_after_inlining): Update to new API. * ipa-utils.c (ipa_merge_profiles): Rewrite merging of speculative call profiles. * profile-count.h: (profile_probability::adjusted): New. * tree-inline.c (copy_bb): Update to new speculative call API; fix updating of profile. * value-prof.c (gimple_ic_transform): Rename to ... (dump_ic_profile): ... this one; update dumping. (stream_in_histogram_value): Fix formating. (gimple_value_profile_transformations): Update. gcc/testsuite/ChangeLog: 2020-01-28 Jan Hubicka <hubi...@ucw.cz> * g++.dg/tree-prof/indir-call-prof.C: Update template. * gcc.dg/tree-prof/crossmodule-indircall-1.c: Add more targets. * gcc.dg/tree-prof/crossmodule-indircall-1a.c: Add more targets. * gcc.dg/tree-prof/indir-call-prof.c: Update template.
