commit badee9820fcf5dca5f8c46c3215ae1779ee7736e
author Nelli Kim <nelli.kim@samsung.com> Fri May 13 13:08:53 2016 +0300
committer Matthew Gharrity <gharrma@google.com> Tue Jun 14 10:05:47 2016 -0700
tree 982948a67a88a1f9a734c935f919f8d307969f48
parent 614968198625a6693666bdc1e5609e2f663f5638

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

compiler/optimizing/code_generator_arm.cc

diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 6e74d08..4fc3b54 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -1873,8 +1873,6 @@
   LocationSummary* locations = invoke->GetLocations();
   Register temp = locations->GetTemp(0).AsRegister<Register>();
   Register hidden_reg = locations->GetTemp(1).AsRegister<Register>();
-  uint32_t method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-      invoke->GetImtIndex() % mirror::Class::kImtSize, kArmPointerSize).Uint32Value();
   Location receiver = locations->InAt(0);
   uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
 
@@ -1900,10 +1898,14 @@
   // intact/accessible until the end of the marking phase (the
   // concurrent copying collector may not in the future).
   __ MaybeUnpoisonHeapReference(temp);
+  __ LoadFromOffset(kLoadWord, temp, temp,
+        mirror::Class::ImtPtrOffset(kArmPointerSize).Uint32Value());
+  uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+      invoke->GetImtIndex() % ImTable::kSize, kArmPointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
+  __ LoadFromOffset(kLoadWord, temp, temp, method_offset);
   uint32_t entry_point =
       ArtMethod::EntryPointFromQuickCompiledCodeOffset(kArmWordSize).Int32Value();
-  __ LoadFromOffset(kLoadWord, temp, temp, method_offset);
   // LR = temp->GetEntryPoint();
   __ LoadFromOffset(kLoadWord, LR, temp, entry_point);
   // LR();
@@ -6777,8 +6779,11 @@
     method_offset = mirror::Class::EmbeddedVTableEntryOffset(
         instruction->GetIndex(), kArmPointerSize).SizeValue();
   } else {
-    method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-        instruction->GetIndex() % mirror::Class::kImtSize, kArmPointerSize).Uint32Value();
+    __ LoadFromOffset(kLoadWord, locations->Out().AsRegister<Register>(),
+        locations->InAt(0).AsRegister<Register>(),
+        mirror::Class::ImtPtrOffset(kArmPointerSize).Uint32Value());
+    method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+        instruction->GetIndex() % ImTable::kSize, kArmPointerSize));
   }
   __ LoadFromOffset(kLoadWord,
                     locations->Out().AsRegister<Register>(),