From b8188b7d7382e4a74af5dd6a125e76e8d43a68a5 Mon Sep 17 00:00:00 2001 From: Martin Jambor Date: Fri, 5 Mar 2021 17:25:20 +0100 Subject: [PATCH] ipa: Fix resolving speculations through cgraph_edge::set_call_stmt In the PR 98078 testcase, speculative call-graph edges which were created by IPA-CP are confirmed during inlining but cgraph_edge::set_call_stmt does not take it very well. The function enters the update_speculative branch and updates the edges in the speculation bundle separately (by a recursive call), but when it processes the first direct edge, most of the bundle actually ceases to exist because it is devirtualized. It nevertheless goes on to attempt to update the indirect edge (that has just been removed), which surprisingly gets as far as adding the edge to the call_site_hash, the same devirtualized edge for the second time, and that triggers an assert. Fixed by this patch which makes the function aware that it is about to resolve a speculation and do so instead of updating components of speculation. Also, it does so before dealing with the hash because the speculation resolution code needs the hash to point to the first speculative direct edge and also cleans the hash up by calling update_call_stmt_hash_for_removing_direct_edge. Bootstrapped and tested on x86_64-linux, also profile-LTO-bootstrapped on the same system. gcc/ChangeLog: 2021-01-20 Martin Jambor PR ipa/98078 * cgraph.c (cgraph_edge::set_call_stmt): Do not update all corresponding speculative edges if we are about to resolve sepculation. Make edge direct (and so resolve speculations) before removing it from call_site_hash. (cgraph_edge::make_direct): Relax the initial assert to allow calling the function on speculative direct edges. --- gcc/cgraph.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/gcc/cgraph.c b/gcc/cgraph.c index db03830..8014075 100644 --- a/gcc/cgraph.c +++ b/gcc/cgraph.c @@ -789,9 +789,22 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt, { tree decl; + cgraph_node *new_direct_callee = NULL; + if ((e->indirect_unknown_callee || e->speculative) + && (decl = gimple_call_fndecl (new_stmt))) + { + /* Constant propagation and especially inlining can turn an indirect call + into a direct one. */ + new_direct_callee = cgraph_node::get (decl); + gcc_checking_assert (new_direct_callee); + } + /* Speculative edges has three component, update all of them when asked to. */ - if (update_speculative && e->speculative) + if (update_speculative && e->speculative + /* If we are about to resolve the speculation by calling make_direct + below, do not bother going over all the speculative edges now. */ + && !new_direct_callee) { cgraph_edge *direct, *indirect, *next; ipa_ref *ref; @@ -821,6 +834,9 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt, return e_indirect ? indirect : direct; } + if (new_direct_callee) + e = make_direct (e, new_direct_callee); + /* Only direct speculative edges go to call_site_hash. */ if (e->caller->call_site_hash && (!e->speculative || !e->indirect_unknown_callee) @@ -831,16 +847,6 @@ cgraph_edge::set_call_stmt (cgraph_edge *e, gcall *new_stmt, (e->call_stmt, cgraph_edge_hasher::hash (e->call_stmt)); e->call_stmt = new_stmt; - if (e->indirect_unknown_callee - && (decl = gimple_call_fndecl (new_stmt))) - { - /* Constant propagation (and possibly also inlining?) can turn an - indirect call into a direct one. */ - cgraph_node *new_callee = cgraph_node::get (decl); - - gcc_checking_assert (new_callee); - e = make_direct (e, new_callee); - } function *fun = DECL_STRUCT_FUNCTION (e->caller->decl); e->can_throw_external = stmt_can_throw_external (fun, new_stmt); @@ -1279,14 +1285,15 @@ cgraph_edge::speculative_call_for_target (cgraph_node *target) return NULL; } -/* Make an indirect edge with an unknown callee an ordinary edge leading to - CALLEE. Speculations can be resolved in the process and EDGE can be removed - and deallocated. Return the edge that now represents the call. */ +/* Make an indirect or speculative EDGE with an unknown callee an ordinary edge + leading to CALLEE. Speculations can be resolved in the process and EDGE can + be removed and deallocated. Return the edge that now represents the + call. */ cgraph_edge * cgraph_edge::make_direct (cgraph_edge *edge, cgraph_node *callee) { - gcc_assert (edge->indirect_unknown_callee); + gcc_assert (edge->indirect_unknown_callee || edge->speculative); /* If we are redirecting speculative call, make it non-speculative. */ if (edge->speculative) -- 2.7.4