Simplify type argument instantiation cache lookup by introducing an array

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1095 matching lines @@
   const bool is_cls_parameterized = cls.NumTypeArguments() > 0;
   ASSERT(!is_cls_parameterized ||
          (cls.type_arguments_field_offset() != Class::kNoTypeArguments));
   // kInlineInstanceSize is a constant used as a threshold for determining
   // when the object initialization should be done as a loop or as
   // straight line code.
   const int kInlineInstanceSize = 12;  // In words.
   const intptr_t instance_size = cls.instance_size();
   ASSERT(instance_size > 0);
   __ LoadObject(R12, Object::null_object(), PP);
-  Label slow_case_with_type_arguments;
+  if (is_cls_parameterized) {
+    __ movq(RDX, Address(RSP, kObjectTypeArgumentsOffset));
+    // RDX: instantiated type arguments.
+  }
   if (FLAG_inline_alloc && Heap::IsAllocatableInNewSpace(instance_size)) {
-    Label slow_case_reload_type_arguments;
-    if (is_cls_parameterized) {
-      __ movq(RDX, Address(RSP, kObjectTypeArgumentsOffset));
-      // RDX: instantiated type arguments.
-    }
+    Label slow_case;
     // Allocate the object and update top to point to
     // next object start and initialize the allocated object.
     // RDX: instantiated type arguments (if is_cls_parameterized).
     Heap* heap = Isolate::Current()->heap();
     __ movq(RCX, Immediate(heap->TopAddress()));
     __ movq(RAX, Address(RCX, 0));
     __ leaq(RBX, Address(RAX, instance_size));
     // Check if the allocation fits into the remaining space.
     // RAX: potential new object start.
     // RBX: potential next object start.
     // RCX: heap top address.
     __ movq(R13, Immediate(heap->EndAddress()));
     __ cmpq(RBX, Address(R13, 0));
     if (FLAG_use_slow_path) {
-      __ jmp(&slow_case_with_type_arguments);
+      __ jmp(&slow_case);
     } else {
-      __ j(ABOVE_EQUAL, &slow_case_with_type_arguments);
+      __ j(ABOVE_EQUAL, &slow_case);
     }
     __ movq(Address(RCX, 0), RBX);
     __ UpdateAllocationStats(cls.id());
 
     // RAX: new object start.
     // RBX: next object start.
     // RDX: new object type arguments (if is_cls_parameterized).
     // Set the tags.
     uword tags = 0;
     tags = RawObject::SizeTag::update(instance_size, tags);
@@ skipping 35 matching lines @@
     if (is_cls_parameterized) {
       // RDX: new object type arguments.
       // Set the type arguments in the new object.
       __ movq(Address(RAX, cls.type_arguments_field_offset()), RDX);
     }
     // Done allocating and initializing the instance.
     // RAX: new object.
     __ addq(RAX, Immediate(kHeapObjectTag));
     __ ret();
 
-    __ Bind(&slow_case_reload_type_arguments);
+    __ Bind(&slow_case);
   }
-  if (is_cls_parameterized) {
-    __ movq(RDX, Address(RSP, kObjectTypeArgumentsOffset));
-  }
-  __ Bind(&slow_case_with_type_arguments);
   // If is_cls_parameterized:
   // RDX: new object type arguments.
   // Create a stub frame.
   __ EnterStubFrame(true);  // Uses PP to access class object.
   __ pushq(R12);  // Setup space on stack for return value.
   __ PushObject(cls, PP);  // Push class of object to be allocated.
   if (is_cls_parameterized) {
     __ pushq(RDX);  // Push type arguments of object to be allocated.
   } else {
     __ pushq(R12);  // Push null type arguments.
@@ skipping 889 matching lines @@
 
   __ movq(left, Address(RSP, 2 * kWordSize));
   __ movq(right, Address(RSP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64