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_mips.cc

diff --git a/compiler/optimizing/code_generator_mips.cc b/compiler/optimizing/code_generator_mips.cc
index ed0767e..c8e927d 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -3701,8 +3701,6 @@
 void InstructionCodeGeneratorMIPS::VisitInvokeInterface(HInvokeInterface* invoke) {
   // TODO: b/18116999, our IMTs can miss an IncompatibleClassChangeError.
   Register temp = invoke->GetLocations()->GetTemp(0).AsRegister<Register>();
-  uint32_t method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-      invoke->GetImtIndex() % mirror::Class::kImtSize, kMipsPointerSize).Uint32Value();
   Location receiver = invoke->GetLocations()->InAt(0);
   uint32_t class_offset = mirror::Object::ClassOffset().Int32Value();
   Offset entry_point = ArtMethod::EntryPointFromQuickCompiledCodeOffset(kMipsWordSize);
@@ -3719,6 +3717,10 @@
     __ LoadFromOffset(kLoadWord, temp, receiver.AsRegister<Register>(), class_offset);
   }
   codegen_->MaybeRecordImplicitNullCheck(invoke);
+  __ LoadFromOffset(kLoadWord, temp, temp,
+      mirror::Class::ImtPtrOffset(kMipsPointerSize).Uint32Value());
+  uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+      invoke->GetImtIndex() % ImTable::kSize, kMipsPointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
   __ LoadFromOffset(kLoadWord, temp, temp, method_offset);
   // T9 = temp->GetEntryPoint();
@@ -5162,8 +5164,12 @@
     method_offset = mirror::Class::EmbeddedVTableEntryOffset(
         instruction->GetIndex(), kMipsPointerSize).SizeValue();
   } else {
-    method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-        instruction->GetIndex() % mirror::Class::kImtSize, kMipsPointerSize).Uint32Value();
+    __ LoadFromOffset(kLoadWord,
+                      locations->Out().AsRegister<Register>(),
+                      locations->InAt(0).AsRegister<Register>(),
+                      mirror::Class::ImtPtrOffset(kMipsPointerSize).Uint32Value());
+    method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+        instruction->GetIndex() % ImTable::kSize, kMipsPointerSize));
   }
   __ LoadFromOffset(kLoadWord,
                     locations->Out().AsRegister<Register>(),