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_x86_64.cc

diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 72de3e6..a8da5f2 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -2228,8 +2228,6 @@
   LocationSummary* locations = invoke->GetLocations();
   CpuRegister temp = locations->GetTemp(0).AsRegister<CpuRegister>();
   CpuRegister hidden_reg = locations->GetTemp(1).AsRegister<CpuRegister>();
-  uint32_t method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-      invoke->GetImtIndex() % mirror::Class::kImtSize, kX86_64PointerSize).Uint32Value();
   Location receiver = locations->InAt(0);
   size_t class_offset = mirror::Object::ClassOffset().SizeValue();
 
@@ -2255,6 +2253,12 @@
   // intact/accessible until the end of the marking phase (the
   // concurrent copying collector may not in the future).
   __ MaybeUnpoisonHeapReference(temp);
+  // temp = temp->GetAddressOfIMT()
+  __ movq(temp,
+      Address(temp, mirror::Class::ImtPtrOffset(kX86_64PointerSize).Uint32Value()));
+  // temp = temp->GetImtEntryAt(method_offset);
+  uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+      invoke->GetImtIndex() % ImTable::kSize, kX86_64PointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
   __ movq(temp, Address(temp, method_offset));
   // call temp->GetEntryPoint();
@@ -3978,8 +3982,11 @@
     method_offset = mirror::Class::EmbeddedVTableEntryOffset(
         instruction->GetIndex(), kX86_64PointerSize).SizeValue();
   } else {
-    method_offset = mirror::Class::EmbeddedImTableEntryOffset(
-        instruction->GetIndex() % mirror::Class::kImtSize, kX86_64PointerSize).Uint32Value();
+    __ movq(locations->Out().AsRegister<CpuRegister>(),
+            Address(locations->InAt(0).AsRegister<CpuRegister>(),
+            mirror::Class::ImtPtrOffset(kX86_64PointerSize).Uint32Value()));
+    method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
+        instruction->GetIndex() % ImTable::kSize, kX86_64PointerSize));
   }
   __ movq(locations->Out().AsRegister<CpuRegister>(),
           Address(locations->InAt(0).AsRegister<CpuRegister>(), method_offset));