More compact string representation on 64 bit.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 733a7bc34d51ae471da51b2ccf409aa19ac72c9d..cbda5c38f6fd8a561f22b4a9a48b5dab92efa4ec 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -655,8 +655,10 @@ void StubCode::GenerateAllocateArrayStub(Assembler* assembler) {
   NOT_IN_PRODUCT(
       __ MaybeTraceAllocation(kArrayCid, &slow_case, Assembler::kFarJump));
 
-  const intptr_t fixed_size = sizeof(RawArray) + kObjectAlignment - 1;
-  __ leaq(RDI, Address(RDI, TIMES_4, fixed_size));  // RDI is a Smi.
+  const intptr_t fixed_size_plus_alignment_padding =
+      sizeof(RawArray) + kObjectAlignment - 1;
+  // RDI is a Smi.
+  __ leaq(RDI, Address(RDI, TIMES_4, fixed_size_plus_alignment_padding));
   ASSERT(kSmiTagShift == 1);
   __ andq(RDI, Immediate(-kObjectAlignment));
 
@@ -897,8 +899,9 @@ void StubCode::GenerateAllocateContextStub(Assembler* assembler) {
     Label slow_case;
     // First compute the rounded instance size.
     // R10: number of context variables.
-    intptr_t fixed_size = (sizeof(RawContext) + kObjectAlignment - 1);
-    __ leaq(R13, Address(R10, TIMES_8, fixed_size));
+    intptr_t fixed_size_plus_alignment_padding =
+        (sizeof(RawContext) + kObjectAlignment - 1);
+    __ leaq(R13, Address(R10, TIMES_8, fixed_size_plus_alignment_padding));
     __ andq(R13, Immediate(-kObjectAlignment));
 
     // Check for allocation tracing.
@@ -942,7 +945,7 @@ void StubCode::GenerateAllocateContextStub(Assembler* assembler) {
     // R10: number of context variables.
     {
       Label size_tag_overflow, done;
-      __ leaq(R13, Address(R10, TIMES_8, fixed_size));
+      __ leaq(R13, Address(R10, TIMES_8, fixed_size_plus_alignment_padding));
       __ andq(R13, Immediate(-kObjectAlignment));
       __ cmpq(R13, Immediate(RawObject::SizeTag::kMaxSizeTag));
       __ j(ABOVE, &size_tag_overflow, Assembler::kNearJump);
@@ -2260,8 +2263,8 @@ void StubCode::GenerateUnlinkedCallStub(Assembler* assembler) {
 void StubCode::GenerateSingleTargetCallStub(Assembler* assembler) {
   Label miss;
   __ LoadClassIdMayBeSmi(RAX, RDI);
-  __ movl(R9, FieldAddress(RBX, SingleTargetCache::lower_limit_offset()));
-  __ movl(R10, FieldAddress(RBX, SingleTargetCache::upper_limit_offset()));
+  __ movzxw(R9, FieldAddress(RBX, SingleTargetCache::lower_limit_offset()));
+  __ movzxw(R10, FieldAddress(RBX, SingleTargetCache::upper_limit_offset()));
   __ cmpq(RAX, R9);
   __ j(LESS, &miss, Assembler::kNearJump);
   __ cmpq(RAX, R10);