diff options
Diffstat (limited to 'gcc/predict.cc')
| -rw-r--r-- | gcc/predict.cc | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/gcc/predict.cc b/gcc/predict.cc index 872f54d..5639d81 100644 --- a/gcc/predict.cc +++ b/gcc/predict.cc @@ -245,7 +245,10 @@ unlikely_executed_edge_p (edge e) { return (e->src->count == profile_count::zero () || e->probability == profile_probability::never ()) - || (e->flags & (EDGE_EH | EDGE_FAKE)); + || (e->flags & EDGE_FAKE) + /* If we read profile and know EH edge is executed, trust it. + Otherwise we consider EH edges never executed. */ + || ((e->flags & EDGE_EH) && !e->probability.reliable_p ()); } /* Return true if edge E of function FUN is probably never executed. */ @@ -830,6 +833,26 @@ unlikely_executed_stmt_p (gimple *stmt) { if (!is_gimple_call (stmt)) return false; + + /* Those calls are inserted by optimizers when code is known to be + unreachable or undefined. */ + if (gimple_call_builtin_p (stmt, BUILT_IN_UNREACHABLE) + || gimple_call_builtin_p (stmt, BUILT_IN_UNREACHABLE_TRAP) + || gimple_call_builtin_p (stmt, BUILT_IN_TRAP)) + return false; + + /* Checks below do not need to be fully reliable. Cold attribute may be + misplaced by user and in the presence of comdat we may result in call to + function with 0 profile having non-zero profile. + + We later detect that profile is lost and will drop the profile of the + comdat. + + So if we think profile count is reliable, do not try to apply these + heuristics. */ + if (gimple_bb (stmt)->count.reliable_p () + && gimple_bb (stmt)->count.nonzero_p ()) + return gimple_bb (stmt)->count == profile_count::zero (); /* NORETURN attribute alone is not strong enough: exit() may be quite likely executed once during program run. */ if (gimple_call_fntype (stmt) @@ -3269,7 +3292,8 @@ tree_estimate_probability (bool dry_run) calculate_dominance_info (CDI_POST_DOMINATORS); /* Decide which edges are known to be unlikely. This improves later branch prediction. */ - determine_unlikely_bbs (); + if (!dry_run) + determine_unlikely_bbs (); bb_predictions = new hash_map<const_basic_block, edge_prediction *>; ssa_expected_value = new hash_map<int_hash<unsigned, 0>, expected_value>; |