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 53f153e2c25d4d1d337309569f7377f94a1654c1..8c7150bd263f32fc7cc5116cf120c174fa02f8d3 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -646,8 +646,10 @@ 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));
 
@@ -888,8 +890,9 @@ 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.
@@ -933,7 +936,7 @@ 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);
@@ -2242,8 +2245,8 @@ 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);