Implement write barrier on ARM.

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/dart_entry.h"
@@ skipping 338 matching lines @@
   __ LeaveStubFrame();
   __ Ret();
 }
 
 
 void StubCode::GenerateAllocateContextStub(Assembler* assembler) {
   __ Unimplemented("AllocateContext stub");
 }
 
 
+DECLARE_LEAF_RUNTIME_ENTRY(void, StoreBufferBlockProcess, Isolate* isolate);
+
+// Helper stub to implement Assembler::StoreIntoObject.
+// Input parameters:
+//   R0: Address (i.e. object) being stored into.
 void StubCode::GenerateUpdateStoreBufferStub(Assembler* assembler) {
-  __ Unimplemented("UpdateStoreBuffer stub");
+  // Save values being destroyed.
+  __ PushList((1 << R1) | (1 << R2) | (1 << R3));
+
+  // Load the isolate out of the context.
+  // Spilled: R1, R2, R3.
+  // R0: Address being stored.
+  __ ldr(R1, FieldAddress(CTX, Context::isolate_offset()));
+
+  // Load top_ out of the StoreBufferBlock and add the address to the pointers_.
+  // R1: Isolate.
+  intptr_t store_buffer_offset = Isolate::store_buffer_block_offset();
+  __ LoadFromOffset(kLoadWord, R2, R1,
+                    store_buffer_offset + StoreBufferBlock::top_offset());
+  __ add(R3, R1, ShifterOperand(R2, LSL, 2));
+  __ StoreToOffset(kStoreWord, R0, R3,
+                   store_buffer_offset + StoreBufferBlock::pointers_offset());
+
+  // Increment top_ and check for overflow.
+  // R2: top_
+  // R1: Isolate
+  Label L;
+  __ add(R2, R2, ShifterOperand(1));
+  __ StoreToOffset(kStoreWord, R2, R1,
+                   store_buffer_offset + StoreBufferBlock::top_offset());
+  __ CompareImmediate(R2, StoreBufferBlock::kSize);
+  // Restore values.
+  __ PopList((1 << R1) | (1 << R2) | (1 << R3));
+  __ b(&L, EQ);
+  __ Ret();
+
+  // Handle overflow: Call the runtime leaf function.
+  __ Bind(&L);
+  // Setup frame, push callee-saved registers.
+
+  __ EnterCallRuntimeFrame(0 * kWordSize);
+  __ ldr(R0, FieldAddress(CTX, Context::isolate_offset()));
+  __ CallRuntime(kStoreBufferBlockProcessRuntimeEntry);
+  // Restore callee-saved registers, tear down frame.
+  __ LeaveCallRuntimeFrame();
+  __ Ret();
 }
 
 
 // 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).
 void StubCode::GenerateAllocationStubForClass(Assembler* assembler,
                                               const Class& cls) {
@@ skipping 668 matching lines @@
   __ Bind(&reference_compare);
   __ cmp(left, ShifterOperand(right));
   __ Bind(&done);
   __ PopList((1 << R0) | (1 << R1) | (1 << R2));
   __ Ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM