Revert "Revert "Refactor GetIMTIndex""

Originally reverted in order to revert
https://android-review.googlesource.com/#/c/244190/
but can now be merged again.

This reverts commit d4ceecc85a5aab2ec23ea1bd010692ba8c8aaa0c.

Test: m test-art-host

Change-Id: Id9205f2b77a378fc0f06088e78c66e81a49f712d
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index a015893..01af1e7 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -2322,7 +2322,7 @@
       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));
+      invoke->GetImtIndex(), kX86_64PointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
   __ movq(temp, Address(temp, method_offset));
   // call temp->GetEntryPoint();
@@ -4048,7 +4048,7 @@
             Address(locations->InAt(0).AsRegister<CpuRegister>(), method_offset));
   } else {
     uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
-        instruction->GetIndex() % ImTable::kSize, kX86_64PointerSize));
+        instruction->GetIndex(), kX86_64PointerSize));
     __ movq(locations->Out().AsRegister<CpuRegister>(),
             Address(locations->InAt(0).AsRegister<CpuRegister>(),
             mirror::Class::ImtPtrOffset(kX86_64PointerSize).Uint32Value()));