commit 6ef45677305048c2bf0600f1c4b98a11b2cfaffb
author Igor Murashkin <iam@google.com> Tue Aug 08 13:59:55 2017 -0700
committer Igor Murashkin <iam@google.com> Fri Aug 11 10:23:30 2017 -0700
tree 9a8df6a3bebe4a6120403562c21817d775a6ef36
parent 1e065a54845da12541572f4f149e6ab0dcd20180

optimizing: Add statistics for # of constructor fences added/removed

Statistics are attributed as follows:

Added because:
* HNewInstances requires a HConstructorFence following it.
* HReturn requires a HConstructorFence (for final fields) preceding it.

Removed because:
* Optimized in Load-Store-Elimination.
* Optimized in Prepare-For-Register-Allocation.

Test: art/test.py
Bug: 36656456
Change-Id: Ic119441c5151a5a840fc6532b411340e2d68e5eb

compiler/optimizing/load_store_elimination.cc

diff --git a/compiler/optimizing/load_store_elimination.cc b/compiler/optimizing/load_store_elimination.cc
index fddda3d..98b8592 100644
--- a/compiler/optimizing/load_store_elimination.cc
+++ b/compiler/optimizing/load_store_elimination.cc
@@ -40,8 +40,9 @@
  public:
   LSEVisitor(HGraph* graph,
              const HeapLocationCollector& heap_locations_collector,
-             const SideEffectsAnalysis& side_effects)
-      : HGraphVisitor(graph),
+             const SideEffectsAnalysis& side_effects,
+             OptimizingCompilerStats* stats)
+      : HGraphVisitor(graph, stats),
         heap_location_collector_(heap_locations_collector),
         side_effects_(side_effects),
         heap_values_for_(graph->GetBlocks().size(),
@@ -100,7 +101,10 @@
     //   * - Constructor fences (they never escape this thread).
     //   * - Allocations (if they are unused).
     for (HInstruction* new_instance : singleton_new_instances_) {
-      HConstructorFence::RemoveConstructorFences(new_instance);
+      size_t removed = HConstructorFence::RemoveConstructorFences(new_instance);
+      MaybeRecordStat(stats_,
+                      MethodCompilationStat::kConstructorFenceRemovedLSE,
+                      removed);
 
       if (!new_instance->HasNonEnvironmentUses()) {
         new_instance->RemoveEnvironmentUsers();
@@ -108,7 +112,10 @@
       }
     }
     for (HInstruction* new_array : singleton_new_arrays_) {
-      HConstructorFence::RemoveConstructorFences(new_array);
+      size_t removed = HConstructorFence::RemoveConstructorFences(new_array);
+      MaybeRecordStat(stats_,
+                      MethodCompilationStat::kConstructorFenceRemovedLSE,
+                      removed);
 
       if (!new_array->HasNonEnvironmentUses()) {
         new_array->RemoveEnvironmentUsers();
@@ -663,7 +670,7 @@
     return;
   }
 
-  LSEVisitor lse_visitor(graph_, heap_location_collector, side_effects_);
+  LSEVisitor lse_visitor(graph_, heap_location_collector, side_effects_, stats_);
   for (HBasicBlock* block : graph_->GetReversePostOrder()) {
     lse_visitor.VisitBasicBlock(block);
   }