Optimize IMT

* Remove IMT for classes which do not implement interfaces
* Remove IMT for array classes
* Share same IMT

Saved memory (measured on hammerhead):
boot.art:
Total number of classes: 3854
Number of affected classes: 1637
Saved memory: 409kB

Chrome (excluding classes in boot.art):
Total number of classes: 2409
Number of affected classes: 1259
Saved memory: 314kB

Google Maps (excluding classes in boot.art):
Total number of classes: 6988
Number of affected classes: 2574
Saved memory: 643kB

Performance regression on benchmarks/InvokeInterface.java benchmark
(measured timeCall10Interface)
1st launch: 9.6%
2nd launch: 6.8%

Change-Id: If07e45390014a6ee8f3c1c4ca095b43046f0871f

1 files changed, 19 insertions, 2 deletions

diff --git a/compiler/driver/compiler_driver.cc b/compiler/driver/compiler_driver.cc
index a4b48892fb..131be37a33 100644
--- a/compiler/driver/compiler_driver.cc
+++ b/compiler/driver/compiler_driver.cc
@@ -2522,11 +2522,28 @@ class InitializeArrayClassesAndCreateConflictTablesVisitor : public ClassVisitor
                                                               true);
     }
     // Create the conflict tables.
-    if (!klass->IsTemp() && klass->ShouldHaveEmbeddedImtAndVTable()) {
+    FillIMTAndConflictTables(klass);
+    return true;
+  }
+
+ private:
+  void FillIMTAndConflictTables(mirror::Class* klass) SHARED_REQUIRES(Locks::mutator_lock_) {
+    if (!klass->ShouldHaveImt()) {
+      return;
+    }
+    if (visited_classes_.find(klass) != visited_classes_.end()) {
+      return;
+    }
+    if (klass->HasSuperClass()) {
+      FillIMTAndConflictTables(klass->GetSuperClass());
+    }
+    if (!klass->IsTemp()) {
       Runtime::Current()->GetClassLinker()->FillIMTAndConflictTables(klass);
     }
-    return true;
+    visited_classes_.insert(klass);
   }
+
+  std::set<mirror::Class*> visited_classes_;
 };
 
 void CompilerDriver::InitializeClasses(jobject class_loader,