Implement KeyedStoreICs to grow arrays on out-of-bound stores.

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index ce35b97c1841ae74d946919449882139b82ed927..506f9b2d5dcdca0ba2de06d5cabf4ac429747fb9 100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -90,11 +90,16 @@ void ElementsTransitionGenerator::GenerateSmiOnlyToDouble(
   //  -- r3    : target map, scratch for subsequent call
   //  -- r4    : scratch (elements)
   // -----------------------------------
-  Label loop, entry, convert_hole, gc_required;
+  Label loop, entry, convert_hole, gc_required, only_change_map, done;
   bool vfp3_supported = CpuFeatures::IsSupported(VFP3);
-  __ push(lr);
 
+  // Check for empty arrays, which only require a map transition and no changes
+  // to the backing store.
   __ ldr(r4, FieldMemOperand(r2, JSObject::kElementsOffset));
+  __ CompareRoot(r4, Heap::kEmptyFixedArrayRootIndex);
+  __ b(eq, &only_change_map);
+
+  __ push(lr);
   __ ldr(r5, FieldMemOperand(r4, FixedArray::kLengthOffset));
   // r4: source FixedArray
   // r5: number of elements (smi-tagged)
@@ -117,7 +122,7 @@ void ElementsTransitionGenerator::GenerateSmiOnlyToDouble(
                       r9,
                       kLRHasBeenSaved,
                       kDontSaveFPRegs,
-                      EMIT_REMEMBERED_SET,
+                      OMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
   // Replace receiver's backing store with newly created FixedDoubleArray.
   __ add(r3, r6, Operand(kHeapObjectTag));
@@ -146,6 +151,18 @@ void ElementsTransitionGenerator::GenerateSmiOnlyToDouble(
 
   __ b(&entry);
 
+  __ bind(&only_change_map);
+  __ str(r3, FieldMemOperand(r2, HeapObject::kMapOffset));
+  __ RecordWriteField(r2,
+                      HeapObject::kMapOffset,
+                      r3,
+                      r9,
+                      kLRHasBeenSaved,
+                      kDontSaveFPRegs,
+                      OMIT_REMEMBERED_SET,
+                      OMIT_SMI_CHECK);
+  __ b(&done);
+
   // Call into runtime if GC is required.
   __ bind(&gc_required);
   __ pop(lr);
@@ -194,6 +211,7 @@ void ElementsTransitionGenerator::GenerateSmiOnlyToDouble(
 
   if (!vfp3_supported) __ Pop(r1, r0);
   __ pop(lr);
+  __ bind(&done);
 }
 
 
@@ -207,10 +225,15 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   //  -- r3    : target map, scratch for subsequent call
   //  -- r4    : scratch (elements)
   // -----------------------------------
-  Label entry, loop, convert_hole, gc_required;
+  Label entry, loop, convert_hole, gc_required, only_change_map;
 
-  __ push(lr);
+  // Check for empty arrays, which only require a map transition and no changes
+  // to the backing store.
   __ ldr(r4, FieldMemOperand(r2, JSObject::kElementsOffset));
+  __ CompareRoot(r4, Heap::kEmptyFixedArrayRootIndex);
+  __ b(eq, &only_change_map);
+
+  __ push(lr);
   __ Push(r3, r2, r1, r0);
   __ ldr(r5, FieldMemOperand(r4, FixedArray::kLengthOffset));
   // r4: source FixedDoubleArray
@@ -280,16 +303,6 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   __ b(lt, &loop);
 
   __ Pop(r3, r2, r1, r0);
-  // Update receiver's map.
-  __ str(r3, FieldMemOperand(r2, HeapObject::kMapOffset));
-  __ RecordWriteField(r2,
-                      HeapObject::kMapOffset,
-                      r3,
-                      r9,
-                      kLRHasBeenSaved,
-                      kDontSaveFPRegs,
-                      EMIT_REMEMBERED_SET,
-                      OMIT_SMI_CHECK);
   // Replace receiver's backing store with newly created and filled FixedArray.
   __ str(r6, FieldMemOperand(r2, JSObject::kElementsOffset));
   __ RecordWriteField(r2,
@@ -301,6 +314,18 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
                       EMIT_REMEMBERED_SET,
                       OMIT_SMI_CHECK);
   __ pop(lr);
+
+  __ bind(&only_change_map);
+  // Update receiver's map.
+  __ str(r3, FieldMemOperand(r2, HeapObject::kMapOffset));
+  __ RecordWriteField(r2,
+                      HeapObject::kMapOffset,
+                      r3,
+                      r9,
+                      kLRHasNotBeenSaved,
+                      kDontSaveFPRegs,
+                      OMIT_REMEMBERED_SET,
+                      OMIT_SMI_CHECK);
 }