Fix allocation stats bug on ARM; add unit test.

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 672 matching lines @@
                               R1);
 
   // Set the length field.
   __ StoreIntoObjectNoBarrier(R0,
                               FieldAddress(R0, Array::length_offset()),
                               R2);
 
   // Initialize all array elements to raw_null.
   // R0: new object start as a tagged pointer.
   // R3: allocation stats address.
+  // R4, R5: null
+  // R6: iterator which initially points to the start of the variable
+  // data area to be initialized.
   // R7: new object end address.
-  // R8: iterator which initially points to the start of the variable
-  // data area to be initialized.
-  // R4, R5: null
+  // R8: allocation size.
+
   __ LoadImmediate(R4, reinterpret_cast<intptr_t>(Object::null()));
   __ mov(R5, Operand(R4));
-  __ AddImmediate(R8, R0, sizeof(RawArray) - kHeapObjectTag);
+  __ AddImmediate(R6, R0, sizeof(RawArray) - kHeapObjectTag);
 
   Label init_loop;
   __ Bind(&init_loop);
-  __ AddImmediate(R8, 2 * kWordSize);
-  __ cmp(R8, Operand(R7));
-  __ strd(R4, Address(R8, -2 * kWordSize), LS);
+  __ AddImmediate(R6, 2 * kWordSize);
+  __ cmp(R6, Operand(R7));
+  __ strd(R4, Address(R6, -2 * kWordSize), LS);
   __ b(&init_loop, CC);
-  __ str(R4, Address(R8, -2 * kWordSize), HI);
+  __ str(R4, Address(R6, -2 * kWordSize), HI);
 
   __ IncrementAllocationStatsWithSize(R3, R8, cid, space);
   __ Ret();  // Returns the newly allocated object in R0.
   // Unable to allocate the array using the fast inline code, just call
   // into the runtime.
   __ Bind(&slow_case);
 
   // Create a stub frame as we are pushing some objects on the stack before
   // calling into the runtime.
   __ EnterStubFrame();
@@ skipping 1269 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