Simplify generated code for object allocation with type arguments.

runtime/vm/stub_code_arm.cc

Index: runtime/vm/stub_code_arm.cc
===================================================================
--- runtime/vm/stub_code_arm.cc	(revision 32653)
+++ runtime/vm/stub_code_arm.cc	(working copy)
@@ -1097,8 +1097,7 @@
 // Called for inline allocation of objects.
 // Input parameters:
 //   LR : return address.
-//   SP + 4 : type arguments object (only if class is parameterized).
-//   SP + 0 : type arguments of instantiator (only if class is parameterized).
+//   SP + 0 : type arguments object (only if class is parameterized).
 void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
                                               const Class& cls) {
   // The generated code is different if the class is parameterized.
@@ -1115,42 +1114,12 @@
   if (FLAG_inline_alloc && Heap::IsAllocatableInNewSpace(instance_size)) {
     Label slow_case_reload_type_arguments;
     if (is_cls_parameterized) {
-      // Instantiation of the type arguments vector is only required if an
-      // instantiator is provided (not kNoInstantiator, but may be null).
-      __ ldm(IA, SP, (1 << R0) | (1 << R1));
-      // R1: type arguments, instantiated or not.
-      // R0: instantiator type arguments or kNoInstantiator.
-      Label type_arguments_ready;
-      __ CompareImmediate(R0, Smi::RawValue(StubCode::kNoInstantiator));
-      __ b(&type_arguments_ready, EQ);
-      // Lookup instantiator R0 in instantiations array of type arguments R1
-      // and, if found, use cached instantiated type arguments.
-      __ ldr(R2, FieldAddress(R1, TypeArguments::instantiations_offset()));
-      __ ldr(R3, FieldAddress(R2, Array::length_offset()));
-      __ AddImmediate(R2, Array::data_offset() - kHeapObjectTag);
-      __ add(R3, R2, ShifterOperand(R3, LSL, 1));  // R3 is Smi.
-      Label loop, found;
-      __ Bind(&loop);
-      __ cmp(R2, ShifterOperand(R3));
-      __ b(&slow_case_reload_type_arguments, CS);  // Unsigned higher or equal.
-      __ ldr(R1, Address(R2, 0 * kWordSize));  // Cached instantiator.
-      __ cmp(R1, ShifterOperand(R0));
-      __ b(&found, EQ);
-      __ CompareImmediate(R1, Smi::RawValue(StubCode::kNoInstantiator));
-      __ b(&slow_case_reload_type_arguments, EQ);
-      __ AddImmediate(R2, 2 * kWordSize);
-      __ b(&loop);
-      __ Bind(&found);
-      __ ldr(R1, Address(R2, 1 * kWordSize));  // Cached instantiated args.
-      __ LoadImmediate(R0, Smi::RawValue(StubCode::kNoInstantiator));
-      __ Bind(&type_arguments_ready);
+      __ ldr(R1, Address(SP, 0));
       // R1: instantiated type arguments.
-      // R0: kNoInstantiator.
     }
     // Allocate the object and update top to point to
     // next object start and initialize the allocated object.
     // R1: instantiated type arguments (if is_cls_parameterized).
-    // R0: kNoInstantiator (if is_cls_parameterized).
     Heap* heap = Isolate::Current()->heap();
     __ LoadImmediate(R5, heap->TopAddress());
     __ ldr(R2, Address(R5, 0));
@@ -1228,12 +1197,11 @@
     __ Bind(&slow_case_reload_type_arguments);
   }
   if (is_cls_parameterized) {
-    __ ldm(IA, SP, (1 << R0) | (1 << R1));
+    __ ldr(R1, Address(SP, 0));
   }
   __ Bind(&slow_case_with_type_arguments);
   // If is_cls_parameterized:
-  // R1: new object type arguments (instantiated or not).
-  // R0: instantiator type arguments or kNoInstantiator.
+  // R1: new object type arguments.
   // Create a stub frame as we are pushing some objects on the stack before
   // calling into the runtime.
   __ EnterStubFrame(true);  // Uses pool pointer to pass cls to runtime.
@@ -1241,15 +1209,14 @@
   __ Push(R2);  // Setup space on stack for return value.
   __ PushObject(cls);  // Push class of object to be allocated.
   if (is_cls_parameterized) {
-    // Push type arguments of object to be allocated and of instantiator.
-    __ PushList((1 << R0) | (1 << R1));
+    // Push type arguments.
+    __ Push(R1);
   } else {
-    // Push null type arguments and kNoInstantiator.
-    __ LoadImmediate(R1, Smi::RawValue(StubCode::kNoInstantiator));
-    __ PushList((1 << R1) | (1 << R2));
+    // Push null type arguments.
+    __ Push(R2);
   }
-  __ CallRuntime(kAllocateObjectRuntimeEntry, 3);  // Allocate object.
-  __ Drop(3);  // Pop arguments.
+  __ CallRuntime(kAllocateObjectRuntimeEntry, 2);  // Allocate object.
+  __ Drop(2);  // Pop arguments.
   __ Pop(R0);  // Pop result (newly allocated object).
   // R0: new object
   // Restore the frame pointer.