Fuse comparisons that are used by branches together.

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
diff --git a/runtime/vm/flow_graph_compiler_x64.cc b/runtime/vm/flow_graph_compiler_x64.cc
index eb4a278059377335990acd5144363e4f78760297..a36b040d81fee2800e0561e5dac4b6e51f9243a2 100644
--- a/runtime/vm/flow_graph_compiler_x64.cc
+++ b/runtime/vm/flow_graph_compiler_x64.cc
@@ -59,8 +59,7 @@ void FlowGraphCompiler::GenerateBoolToJump(Register bool_register,
   Label fall_through;
   __ cmpq(bool_register, raw_null);
   __ j(EQUAL, &fall_through, Assembler::kNearJump);
-  const Bool& bool_true = Bool::ZoneHandle(Bool::True());
-  __ CompareObject(bool_register, bool_true);
+  __ CompareObject(bool_register, bool_true());
   __ j(EQUAL, is_true);
   __ jmp(is_false);
   __ Bind(&fall_through);
@@ -566,8 +565,6 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t cid,
                                            const AbstractType& type,
                                            bool negate_result) {
   ASSERT(type.IsFinalized() && !type.IsMalformed());
-  const Bool& bool_true = Bool::ZoneHandle(Bool::True());
-  const Bool& bool_false = Bool::ZoneHandle(Bool::False());
 
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
@@ -612,21 +609,21 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t cid,
   Label done;
   if (negate_result) {
     __ popq(RDX);
-    __ LoadObject(RAX, bool_true);
+    __ LoadObject(RAX, bool_true());
     __ cmpq(RDX, RAX);
     __ j(NOT_EQUAL, &done, Assembler::kNearJump);
-    __ LoadObject(RAX, bool_false);
+    __ LoadObject(RAX, bool_false());
   } else {
     __ popq(RAX);
   }
   __ jmp(&done, Assembler::kNearJump);
 
   __ Bind(&is_not_instance);
-  __ LoadObject(RAX, negate_result ? bool_true : bool_false);
+  __ LoadObject(RAX, negate_result ? bool_true() : bool_false());
   __ jmp(&done, Assembler::kNearJump);
 
   __ Bind(&is_instance);
-  __ LoadObject(RAX, negate_result ? bool_false : bool_true);
+  __ LoadObject(RAX, negate_result ? bool_false() : bool_true());
   __ Bind(&done);
   __ popq(RDX);  // Remove pushed instantiator type arguments.
   __ popq(RCX);  // Remove pushed instantiator.