Allow invalidation and recompilation of instance allocation stubs. Requested in order to implement…

runtime/vm/stub_code_arm.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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/cpu.h"
@@ skipping 375 matching lines @@
   __ PopList((1 << R0) | (1 << R4));
   // Remove the stub frame.
   __ LeaveStubFrame();
   // Jump to the dart function.
   __ ldr(R0, FieldAddress(R0, Code::instructions_offset()));
   __ AddImmediate(R0, R0, Instructions::HeaderSize() - kHeapObjectTag);
   __ bx(R0);
 }
 
 
+// Called from object allocate instruction when the allocation stub has been
+// disabled.
+void StubCode::GenerateFixAllocationStubTargetStub(Assembler* assembler) {
+  __ EnterStubFrame();
+  // Setup space on stack for return value.
+  __ LoadImmediate(R0, reinterpret_cast<intptr_t>(Object::null()));
+  __ Push(R0);
+  __ CallRuntime(kFixAllocationStubTargetRuntimeEntry, 0);
+  // Get Code object result.
+  __ Pop(R0);
+  // Remove the stub frame.
+  __ LeaveStubFrame();
+  // Jump to the dart function.
+  __ ldr(R0, FieldAddress(R0, Code::instructions_offset()));
+  __ AddImmediate(R0, R0, Instructions::HeaderSize() - kHeapObjectTag);
+  __ bx(R0);
+}
+
+
 // Input parameters:
 //   R2: smi-tagged argument count, may be zero.
 //   FP[kParamEndSlotFromFp + 1]: last argument.
 static void PushArgumentsArray(Assembler* assembler) {
   StubCode* stub_code = Isolate::Current()->stub_code();
   // Allocate array to store arguments of caller.
   __ LoadImmediate(R1, reinterpret_cast<intptr_t>(Object::null()));
   // R1: null element type for raw Array.
   // R2: smi-tagged argument count, may be zero.
   __ BranchLink(&stub_code->AllocateArrayLabel());
@@ skipping 614 matching lines @@
   // Restore callee-saved registers, tear down frame.
   __ LeaveCallRuntimeFrame();
   __ Ret();
 }
 
 
 // Called for inline allocation of objects.
 // Input parameters:
 //   LR : return address.
 //   SP + 0 : type arguments object (only if class is parameterized).
-void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
-                                              const Class& cls) {
+// Returns patch_code_pc offset where patching code for disabling the stub
+// has been generated (similar to regularly generated Dart code).
+uword StubCode::GenerateAllocationStubForClass(Assembler* assembler,
+                                               const Class& cls) {
   // The generated code is different if the class is parameterized.
   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;
   const intptr_t instance_size = cls.instance_size();
   ASSERT(instance_size > 0);
@@ skipping 97 matching lines @@
     // Push null type arguments.
     __ Push(R2);
   }
   __ CallRuntime(kAllocateObjectRuntimeEntry, 2);  // Allocate object.
   __ Drop(2);  // Pop arguments.
   __ Pop(R0);  // Pop result (newly allocated object).
   // R0: new object
   // Restore the frame pointer.
   __ LeaveStubFrame();
   __ Ret();
+  uword patch_code_pc_offset = assembler->CodeSize();
+  StubCode* stub_code = Isolate::Current()->stub_code();
+  __ BranchPatchable(&stub_code->FixAllocationStubTargetLabel());
+  return patch_code_pc_offset;
 }
 
 
 // Called for invoking "dynamic noSuchMethod(Invocation invocation)" function
 // from the entry code of a dart function after an error in passed argument
 // name or number is detected.
 // Input parameters:
 //  LR : return address.
 //  SP : address of last argument.
 //  R4: arguments descriptor array.
@@ skipping 787 matching lines @@
   const Register right = R0;
   __ ldr(left, Address(SP, 1 * kWordSize));
   __ ldr(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM