optimizing: add block-scoped constructor fence merging pass
Introduce a new "Constructor Fence Redundancy Elimination" pass.
The pass currently performs local optimization only, i.e. within instructions
in the same basic block.
All constructor fences preceding a publish (e.g. store, invoke) get
merged into one instruction.
==============
OptStat#ConstructorFenceGeneratedNew: 43825
OptStat#ConstructorFenceGeneratedFinal: 17631 <+++
OptStat#ConstructorFenceRemovedLSE: 164
OptStat#ConstructorFenceRemovedPFRA: 9391
OptStat#ConstructorFenceRemovedCFRE: 16133 <---
Removes ~91.5% of the 'final' constructor fences in RitzBenchmark:
(We do not distinguish the exact reason that a fence was created, so
it's possible some "new" fences were also removed.)
==============
Test: art/test/run-test --host --optimizing 476-checker-ctor-fence-redun-elim
Bug: 36656456
Change-Id: I8020217b448ad96ce9b7640aa312ae784690ad99
diff --git a/compiler/optimizing/optimizing_compiler_stats.h b/compiler/optimizing/optimizing_compiler_stats.h
index d6da73c..af7ab2f 100644
--- a/compiler/optimizing/optimizing_compiler_stats.h
+++ b/compiler/optimizing/optimizing_compiler_stats.h
@@ -91,6 +91,7 @@
kConstructorFenceGeneratedFinal,
kConstructorFenceRemovedLSE,
kConstructorFenceRemovedPFRA,
+ kConstructorFenceRemovedCFRE,
kLastStat
};
@@ -211,6 +212,7 @@
case kConstructorFenceGeneratedFinal: name = "ConstructorFenceGeneratedFinal"; break;
case kConstructorFenceRemovedLSE: name = "ConstructorFenceRemovedLSE"; break;
case kConstructorFenceRemovedPFRA: name = "ConstructorFenceRemovedPFRA"; break;
+ case kConstructorFenceRemovedCFRE: name = "ConstructorFenceRemovedCFRE"; break;
case kLastStat:
LOG(FATAL) << "invalid stat "