Better support for 'polymorphic' JS and external arrays

src/arm/stub-cache-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3066 matching lines @@
 
   GenerateLoadFunctionPrototype(masm(), r1, r2, r3, &miss);
   __ bind(&miss);
   __ DecrementCounter(counters->keyed_load_function_prototype(), 1, r2, r3);
   GenerateLoadMiss(masm(), Code::KEYED_LOAD_IC);
 
   return GetCode(CALLBACKS, name);
 }
 
 
-MaybeObject* KeyedLoadStubCompiler::CompileLoadSpecialized(JSObject* receiver) {
+MaybeObject* KeyedLoadStubCompiler::CompileLoadFastElement(Map* receiver_map) {
+  // ----------- S t a t e -------------
+  //  -- lr    : return address
+  //  -- r0    : key
+  //  -- r1    : receiver
+  // -----------------------------------
+  MaybeObject* maybe_stub = KeyedLoadFastElementStub().TryGetCode();
+  Code* stub;
+  if (!maybe_stub->To(&stub)) return maybe_stub;
+  __ DispatchMap(r1,
+                 r2,
+                 Handle<Map>(receiver_map),
+                 Handle<Code>(stub),
+                 false);
+
+  Handle<Code> ic = isolate()->builtins()->KeyedLoadIC_Miss();
+  __ Jump(ic, RelocInfo::CODE_TARGET);
+
+  // Return the generated code.
+  return GetCode(NORMAL, NULL);
+}
+
+
+MaybeObject* KeyedLoadStubCompiler::CompileLoadMegamorphic(
+    MapList* receiver_maps,
+    CodeList* handler_ics) {
   // ----------- S t a t e -------------
   //  -- lr    : return address
   //  -- r0    : key
   //  -- r1    : receiver
   // -----------------------------------
   Label miss;
+  __ JumpIfSmi(r1, &miss);
 
-  // Check that the receiver isn't a smi.
-  __ tst(r1, Operand(kSmiTagMask));
-  __ b(eq, &miss);
-
-  // Check that the map matches.
-  __ ldr(r2, FieldMemOperand(r1, HeapObject::kMapOffset));
-  __ cmp(r2, Operand(Handle<Map>(receiver->map())));
-  __ b(ne, &miss);
-
-  // Check that the key is a smi.
-  __ tst(r0, Operand(kSmiTagMask));
-  __ b(ne, &miss);
-
-  // Get the elements array.
-  __ ldr(r2, FieldMemOperand(r1, JSObject::kElementsOffset));
-  __ AssertFastElements(r2);
-
-  // Check that the key is within bounds.
-  __ ldr(r3, FieldMemOperand(r2, FixedArray::kLengthOffset));
-  __ cmp(r0, Operand(r3));
-  __ b(hs, &miss);
-
-  // Load the result and make sure it's not the hole.
-  __ add(r3, r2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-  ASSERT(kSmiTag == 0 && kSmiTagSize < kPointerSizeLog2);
-  __ ldr(r4,
-         MemOperand(r3, r0, LSL, kPointerSizeLog2 - kSmiTagSize));
-  __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
-  __ cmp(r4, ip);
-  __ b(eq, &miss);
-  __ mov(r0, r4);
-  __ Ret();
+  int receiver_count = receiver_maps->length();
+  for (int current = 0; current < receiver_count; ++current) {
+    // Check map and tail call if there's a match
+    __ DispatchMap(r1,
+                   r2,
+                   Handle<Map>(receiver_maps->at(current)),
+                   Handle<Code>(handler_ics->at(current)),
+                   true);

[Mads Ager (chromium), 2011/05/12 09:42:47]

I already forgot what this boolean is. Using an enum value would make it easier
to read.

[danno, 2011/06/01 13:16:08]

Done.

+  }
 
   __ bind(&miss);
-  GenerateLoadMiss(masm(), Code::KEYED_LOAD_IC);
+  Handle<Code> miss_ic = isolate()->builtins()->KeyedLoadIC_Miss();
+  __ Jump(miss_ic, RelocInfo::CODE_TARGET, al);
 
   // Return the generated code.
-  return GetCode(NORMAL, NULL);
+  return GetCode(NORMAL, NULL, MEGAMORPHIC);
 }
 
 
 MaybeObject* KeyedStoreStubCompiler::CompileStoreField(JSObject* object,
                                                        int index,
                                                        Map* transition,
                                                        String* name) {
   // ----------- S t a t e -------------
   //  -- r0    : value
   //  -- r1    : name
@@ skipping 21 matching lines @@
 
   __ DecrementCounter(counters->keyed_store_field(), 1, r3, r4);
   Handle<Code> ic = masm()->isolate()->builtins()->KeyedStoreIC_Miss();
   __ Jump(ic, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode(transition == NULL ? FIELD : MAP_TRANSITION, name);
 }
 
 
-MaybeObject* KeyedStoreStubCompiler::CompileStoreSpecialized(
-    JSObject* receiver) {
+MaybeObject* KeyedStoreStubCompiler::CompileStoreFastElement(
+    Map* receiver_map) {
   // ----------- S t a t e -------------
   //  -- r0    : value
   //  -- r1    : key
   //  -- r2    : receiver
   //  -- lr    : return address
   //  -- r3    : scratch
-  //  -- r4    : scratch (elements)
   // -----------------------------------
-  Label miss;
+  bool is_js_array = receiver_map->instance_type() == JS_ARRAY_TYPE;
+  MaybeObject* maybe_stub =
+      KeyedStoreFastElementStub(is_js_array).TryGetCode();
+  Code* stub;
+  if (!maybe_stub->To(&stub)) return maybe_stub;
+  __ DispatchMap(r2,
+                 r3,
+                 Handle<Map>(receiver_map),
+                 Handle<Code>(stub),
+                 false);
 
-  Register value_reg = r0;
-  Register key_reg = r1;
-  Register receiver_reg = r2;
-  Register scratch = r3;
-  Register elements_reg = r4;
-
-  // Check that the receiver isn't a smi.
-  __ tst(receiver_reg, Operand(kSmiTagMask));
-  __ b(eq, &miss);
-
-  // Check that the map matches.
-  __ ldr(scratch, FieldMemOperand(receiver_reg, HeapObject::kMapOffset));
-  __ cmp(scratch, Operand(Handle<Map>(receiver->map())));
-  __ b(ne, &miss);
-
-  // Check that the key is a smi.
-  __ tst(key_reg, Operand(kSmiTagMask));
-  __ b(ne, &miss);
-
-  // Get the elements array and make sure it is a fast element array, not 'cow'.
-  __ ldr(elements_reg,
-         FieldMemOperand(receiver_reg, JSObject::kElementsOffset));
-  __ ldr(scratch, FieldMemOperand(elements_reg, HeapObject::kMapOffset));
-  __ cmp(scratch, Operand(Handle<Map>(factory()->fixed_array_map())));
-  __ b(ne, &miss);
-
-  // Check that the key is within bounds.
-  if (receiver->IsJSArray()) {
-    __ ldr(scratch, FieldMemOperand(receiver_reg, JSArray::kLengthOffset));
-  } else {
-    __ ldr(scratch, FieldMemOperand(elements_reg, FixedArray::kLengthOffset));
-  }
-  // Compare smis.
-  __ cmp(key_reg, scratch);
-  __ b(hs, &miss);
-
-  __ add(scratch,
-         elements_reg, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
-  ASSERT(kSmiTag == 0 && kSmiTagSize < kPointerSizeLog2);
-  __ str(value_reg,
-         MemOperand(scratch, key_reg, LSL, kPointerSizeLog2 - kSmiTagSize));
-  __ RecordWrite(scratch,
-                 Operand(key_reg, LSL, kPointerSizeLog2 - kSmiTagSize),
-                 receiver_reg , elements_reg);
-
-  // value_reg (r0) is preserved.
-  // Done.
-  __ Ret();
-
-  __ bind(&miss);
-  Handle<Code> ic = masm()->isolate()->builtins()->KeyedStoreIC_Miss();
+  Handle<Code> ic = isolate()->builtins()->KeyedStoreIC_Miss();
   __ Jump(ic, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode(NORMAL, NULL);
 }
 
 
+MaybeObject* KeyedStoreStubCompiler::CompileStoreMegamorphic(
+    MapList* receiver_maps,
+    CodeList* handler_ics) {
+  // ----------- S t a t e -------------
+  //  -- r0    : value
+  //  -- r1    : key
+  //  -- r2    : receiver
+  //  -- lr    : return address
+  //  -- r3    : scratch
+  // -----------------------------------
+  Label miss;
+  __ JumpIfSmi(r2, &miss);
+
+  int receiver_count = receiver_maps->length();
+  for (int current = 0; current < receiver_count; ++current) {
+    // Check map and tail call if there's a match
+    __ DispatchMap(r2,
+                   r3,
+                   Handle<Map>(receiver_maps->at(current)),
+                   Handle<Code>(handler_ics->at(current)),
+                   true);
+  }
+
+  __ bind(&miss);
+  Handle<Code> miss_ic = isolate()->builtins()->KeyedStoreIC_Miss();
+  __ Jump(miss_ic, RelocInfo::CODE_TARGET, al);
+
+  // Return the generated code.
+  return GetCode(NORMAL, NULL, MEGAMORPHIC);
+}
+
+
 MaybeObject* ConstructStubCompiler::CompileConstructStub(JSFunction* function) {
   // ----------- S t a t e -------------
   //  -- r0    : argc
   //  -- r1    : constructor
   //  -- lr    : return address
   //  -- [sp]  : last argument
   // -----------------------------------
   Label generic_stub_call;
 
   // Use r7 for holding undefined which is used in several places below.
@@ skipping 124 matching lines @@
   // construction.
   __ bind(&generic_stub_call);
   Handle<Code> code = masm()->isolate()->builtins()->JSConstructStubGeneric();
   __ Jump(code, RelocInfo::CODE_TARGET);
 
   // Return the generated code.
   return GetCode();
 }
 
 
+MaybeObject* ExternalArrayLoadStubCompiler::CompileLoad(
+    JSObject*receiver, ExternalArrayType array_type) {
+  // ----------- S t a t e -------------
+  //  -- lr    : return address
+  //  -- r0    : key
+  //  -- r1    : receiver
+  // -----------------------------------
+  MaybeObject* maybe_stub =
+      KeyedLoadExternalArrayStub(array_type).TryGetCode();
+  Code* stub;
+  if (!maybe_stub->To(&stub)) return maybe_stub;
+  __ DispatchMap(r1,
+                 r2,
+                 Handle<Map>(receiver->map()),
+                 Handle<Code>(stub),
+                 false);
+
+  Handle<Code> ic = isolate()->builtins()->KeyedLoadIC_Miss();
+  __ Jump(ic, RelocInfo::CODE_TARGET);
+
+  // Return the generated code.
+  return GetCode();
+}
+
+
+MaybeObject* ExternalArrayStoreStubCompiler::CompileStore(
+    JSObject* receiver, ExternalArrayType array_type) {
+  // ----------- S t a t e -------------
+  //  -- r0    : value
+  //  -- r1    : name
+  //  -- r2    : receiver
+  //  -- lr    : return address
+  // -----------------------------------
+  MaybeObject* maybe_stub =
+      KeyedStoreExternalArrayStub(array_type).TryGetCode();
+  Code* stub;
+  if (!maybe_stub->To(&stub)) return maybe_stub;
+  __ DispatchMap(r2,
+                 r3,
+                 Handle<Map>(receiver->map()),
+                 Handle<Code>(stub),
+                 false);
+
+  Handle<Code> ic = isolate()->builtins()->KeyedStoreIC_Miss();
+  __ Jump(ic, RelocInfo::CODE_TARGET);
+
+  return GetCode();
+}
+
+
+#undef __
+#define __ ACCESS_MASM(masm)
+
+
 static bool IsElementTypeSigned(ExternalArrayType array_type) {
   switch (array_type) {
     case kExternalByteArray:
     case kExternalShortArray:
     case kExternalIntArray:
       return true;
 
     case kExternalUnsignedByteArray:
     case kExternalUnsignedShortArray:
     case kExternalUnsignedIntArray:
       return false;
 
     default:
       UNREACHABLE();
       return false;
   }
 }
 
 
-MaybeObject* ExternalArrayStubCompiler::CompileKeyedLoadStub(
-    JSObject* receiver_object,
-    ExternalArrayType array_type,
-    Code::Flags flags) {
+void KeyedLoadStubCompiler::GenerateLoadExternalArray(
+    MacroAssembler* masm,
+    ExternalArrayType array_type) {
   // ---------- S t a t e --------------
   //  -- lr     : return address
   //  -- r0     : key
   //  -- r1     : receiver
   // -----------------------------------
-  Label slow, failed_allocation;
+  Label miss_force_generic, slow, failed_allocation;
 
   Register key = r0;
   Register receiver = r1;
 
-  // Check that the object isn't a smi
-  __ JumpIfSmi(receiver, &slow);
+  // This stub is meant to be tail-jumped to, the receiver must already
+  // have been verified by the caller to not be a smi.
 
   // Check that the key is a smi.
-  __ JumpIfNotSmi(key, &slow);
-
-  // Make sure that we've got the right map.
-  __ ldr(r2, FieldMemOperand(receiver, HeapObject::kMapOffset));
-  __ cmp(r2, Operand(Handle<Map>(receiver_object->map())));
-  __ b(ne, &slow);
+  __ JumpIfNotSmi(key, &miss_force_generic);
 
   __ ldr(r3, FieldMemOperand(receiver, JSObject::kElementsOffset));
   // r3: elements array
 
   // Check that the index is in range.
   __ ldr(ip, FieldMemOperand(r3, ExternalArray::kLengthOffset));
   __ cmp(ip, Operand(key, ASR, kSmiTagSize));
   // Unsigned comparison catches both negative and too-large values.
-  __ b(lo, &slow);
+  __ b(lo, &miss_force_generic);
 
   __ ldr(r3, FieldMemOperand(r3, ExternalArray::kExternalPointerOffset));
   // r3: base pointer of external storage
 
   // We are not untagging smi key and instead work with it
   // as if it was premultiplied by 2.
   ASSERT((kSmiTag == 0) && (kSmiTagSize == 1));
 
   Register value = r2;
   switch (array_type) {
@@ skipping 116 matching lines @@
       __ b(ne, &box_int_1);
       // Tag integer as smi and return it.
       __ mov(r0, Operand(value, LSL, kSmiTagSize));
       __ Ret();
 
       Register hiword = value;  // r2.
       Register loword = r3;
 
       __ bind(&box_int_0);
       // Integer does not have leading zeros.
-      GenerateUInt2Double(masm(), hiword, loword, r4, 0);
+      GenerateUInt2Double(masm, hiword, loword, r4, 0);
       __ b(&done);
 
       __ bind(&box_int_1);
       // Integer has one leading zero.
-      GenerateUInt2Double(masm(), hiword, loword, r4, 1);
+      GenerateUInt2Double(masm, hiword, loword, r4, 1);
 
 
       __ bind(&done);
       // Integer was converted to double in registers hiword:loword.
       // Wrap it into a HeapNumber. Don't use r0 and r1 as AllocateHeapNumber
       // clobbers all registers - also when jumping due to exhausted young
       // space.
       __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
       __ AllocateHeapNumber(r4, r5, r7, r6, &slow);
 
@@ skipping 101 matching lines @@
 
   } else {
     // Tag integer as smi and return it.
     __ mov(r0, Operand(value, LSL, kSmiTagSize));
     __ Ret();
   }
 
   // Slow case, key and receiver still in r0 and r1.
   __ bind(&slow);
   __ IncrementCounter(
-      masm()->isolate()->counters()->keyed_load_external_array_slow(),
+      masm->isolate()->counters()->keyed_load_external_array_slow(),
       1, r2, r3);
 
   // ---------- S t a t e --------------
   //  -- lr     : return address
   //  -- r0     : key
   //  -- r1     : receiver
   // -----------------------------------
 
   __ Push(r1, r0);
 
   __ TailCallRuntime(Runtime::kKeyedGetProperty, 2, 1);
 
-  return GetCode(flags);
+  __ bind(&miss_force_generic);
+  Code* stub = masm->isolate()->builtins()->builtin(
+      Builtins::kKeyedLoadIC_MissForceGeneric);
+  __ Jump(Handle<Code>(stub), RelocInfo::CODE_TARGET);
 }
 
 
-MaybeObject* ExternalArrayStubCompiler::CompileKeyedStoreStub(
-    JSObject* receiver_object,
-    ExternalArrayType array_type,
-    Code::Flags flags) {
+void KeyedStoreStubCompiler::GenerateStoreExternalArray(
+    MacroAssembler* masm,
+    ExternalArrayType array_type) {
   // ---------- S t a t e --------------
   //  -- r0     : value
   //  -- r1     : key
   //  -- r2     : receiver
   //  -- lr     : return address
   // -----------------------------------
-  Label slow, check_heap_number;
+  Label slow, check_heap_number, miss_force_generic;
 
   // Register usage.
   Register value = r0;
   Register key = r1;
   Register receiver = r2;
   // r3 mostly holds the elements array or the destination external array.
 
-  // Check that the object isn't a smi.
-  __ JumpIfSmi(receiver, &slow);
-
-  // Make sure that we've got the right map.
-  __ ldr(r3, FieldMemOperand(receiver, HeapObject::kMapOffset));
-  __ cmp(r3, Operand(Handle<Map>(receiver_object->map())));
-  __ b(ne, &slow);
+  // This stub is meant to be tail-jumped to, the receiver must already
+  // have been verified by the caller to not be a smi.
 
   __ ldr(r3, FieldMemOperand(receiver, JSObject::kElementsOffset));
 
   // Check that the key is a smi.
-  __ JumpIfNotSmi(key, &slow);
+  __ JumpIfNotSmi(key, &miss_force_generic);
 
   // Check that the index is in range
   __ SmiUntag(r4, key);
   __ ldr(ip, FieldMemOperand(r3, ExternalArray::kLengthOffset));
   __ cmp(r4, ip);
   // Unsigned comparison catches both negative and too-large values.
-  __ b(hs, &slow);
+  __ b(hs, &miss_force_generic);
 
   // Handle both smis and HeapNumbers in the fast path. Go to the
   // runtime for all other kinds of values.
   // r3: external array.
   // r4: key (integer).
   if (array_type == kExternalPixelArray) {
     // Double to pixel conversion is only implemented in the runtime for now.
     __ JumpIfNotSmi(value, &slow);
   } else {
     __ JumpIfNotSmi(value, &check_heap_number);
@@ skipping 17 matching lines @@
     case kExternalShortArray:
     case kExternalUnsignedShortArray:
       __ strh(r5, MemOperand(r3, r4, LSL, 1));
       break;
     case kExternalIntArray:
     case kExternalUnsignedIntArray:
       __ str(r5, MemOperand(r3, r4, LSL, 2));
       break;
     case kExternalFloatArray:
       // Perform int-to-float conversion and store to memory.
-      StoreIntAsFloat(masm(), r3, r4, r5, r6, r7, r9);
+      StoreIntAsFloat(masm, r3, r4, r5, r6, r7, r9);
       break;
     case kExternalDoubleArray:
       __ add(r3, r3, Operand(r4, LSL, 3));
       // r3: effective address of the double element
       FloatingPointHelper::Destination destination;
       if (CpuFeatures::IsSupported(VFP3)) {
         destination = FloatingPointHelper::kVFPRegisters;
       } else {
         destination = FloatingPointHelper::kCoreRegisters;
       }
       FloatingPointHelper::ConvertIntToDouble(
-          masm(), r5, destination,
+          masm, r5, destination,
           d0, r6, r7,  // These are: double_dst, dst1, dst2.
           r4, s2);  // These are: scratch2, single_scratch.
       if (destination == FloatingPointHelper::kVFPRegisters) {
         CpuFeatures::Scope scope(VFP3);
         __ vstr(d0, r3, 0);
       } else {
         __ str(r6, MemOperand(r3, 0));
         __ str(r7, MemOperand(r3, Register::kSizeInBytes));
       }
       break;
@@ skipping 206 matching lines @@
             __ str(r5, MemOperand(r3, r4, LSL, 2));
             break;
           default:
             UNREACHABLE();
             break;
         }
       }
     }
   }
 
-  // Slow case: call runtime.
+  // Slow case, key and receiver still in r0 and r1.
   __ bind(&slow);
+  __ IncrementCounter(
+      masm->isolate()->counters()->keyed_load_external_array_slow(),
+      1, r2, r3);
 
-  // Entry registers are intact.
   // ---------- S t a t e --------------
-  //  -- r0     : value
-  //  -- r1     : key
-  //  -- r2     : receiver
   //  -- lr     : return address
+  //  -- r0     : key
+  //  -- r1     : receiver
+  // -----------------------------------
+  Handle<Code> slow_ic =
+      masm->isolate()->builtins()->KeyedStoreIC_Slow();
+  __ Jump(slow_ic, RelocInfo::CODE_TARGET);
+
+  // Miss case, call the runtime.
+  __ bind(&miss_force_generic);
+
+  // ---------- S t a t e --------------
+  //  -- lr     : return address
+  //  -- r0     : key
+  //  -- r1     : receiver
   // -----------------------------------
 
-  // Push receiver, key and value for runtime call.
-  __ Push(r2, r1, r0);
-
-  __ mov(r1, Operand(Smi::FromInt(NONE)));  // PropertyAttributes
-  __ mov(r0, Operand(Smi::FromInt(
-      Code::ExtractExtraICStateFromFlags(flags) & kStrictMode)));
-  __ Push(r1, r0);
-
-  __ TailCallRuntime(Runtime::kSetProperty, 5, 1);
-
-  return GetCode(flags);
+  Handle<Code> miss_ic =
+      masm->isolate()->builtins()->KeyedStoreIC_MissForceGeneric();
+  __ Jump(miss_ic, RelocInfo::CODE_TARGET);
 }
 
 
+void KeyedLoadStubCompiler::GenerateLoadFastElement(MacroAssembler* masm) {
+  // ----------- S t a t e -------------
+  //  -- lr    : return address
+  //  -- r0    : key
+  //  -- r1    : receiver
+  // -----------------------------------
+  Label miss_force_generic;
+
+  // This stub is meant to be tail-jumped to, the receiver must already
+  // have been verified by the caller to not be a smi.
+
+  // Check that the key is a smi.
+  __ tst(r0, Operand(kSmiTagMask));

[Mads Ager (chromium), 2011/05/12 09:42:47]

Use JumpIfNotSmi?

[danno, 2011/06/01 13:16:08]

Done.

+  __ b(ne, &miss_force_generic);
+
+  // Get the elements array.
+  __ ldr(r2, FieldMemOperand(r1, JSObject::kElementsOffset));
+  __ AssertFastElements(r2);
+
+  // Check that the key is within bounds.
+  __ ldr(r3, FieldMemOperand(r2, FixedArray::kLengthOffset));
+  __ cmp(r0, Operand(r3));
+  __ b(hs, &miss_force_generic);
+
+  // Load the result and make sure it's not the hole.
+  __ add(r3, r2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  ASSERT(kSmiTag == 0 && kSmiTagSize < kPointerSizeLog2);
+  __ ldr(r4,
+         MemOperand(r3, r0, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
+  __ cmp(r4, ip);
+  __ b(eq, &miss_force_generic);
+  __ mov(r0, r4);
+  __ Ret();
+
+  __ bind(&miss_force_generic);
+  Code* stub = masm->isolate()->builtins()->builtin(
+      Builtins::kKeyedLoadIC_MissForceGeneric);
+  __ Jump(Handle<Code>(stub), RelocInfo::CODE_TARGET);
+}
+
+
+void KeyedStoreStubCompiler::GenerateStoreFastElement(MacroAssembler* masm,
+                                                      bool is_js_array) {
+  // ----------- S t a t e -------------
+  //  -- r0    : value
+  //  -- r1    : key
+  //  -- r2    : receiver
+  //  -- lr    : return address
+  //  -- r3    : scratch
+  //  -- r4    : scratch (elements)
+  // -----------------------------------
+  Label miss_force_generic;
+
+  Register value_reg = r0;
+  Register key_reg = r1;
+  Register receiver_reg = r2;
+  Register scratch = r3;
+  Register elements_reg = r4;
+
+  // This stub is meant to be tail-jumped to, the receiver must already
+  // have been verified by the caller to not be a smi.
+
+  // Check that the key is a smi.
+  __ tst(key_reg, Operand(kSmiTagMask));

[Mads Ager (chromium), 2011/05/12 09:42:47]

JumpIfNotSmi?

[danno, 2011/06/01 13:16:08]

Done.

+  __ b(ne, &miss_force_generic);
+
+  // Get the elements array and make sure it is a fast element array, not 'cow'.
+  __ ldr(elements_reg,
+         FieldMemOperand(receiver_reg, JSObject::kElementsOffset));
+  __ ldr(scratch, FieldMemOperand(elements_reg, HeapObject::kMapOffset));

[Mads Ager (chromium), 2011/05/12 09:42:47]

Can you use CheckMap with kFixedArrayMapRootIndex here?

[danno, 2011/06/01 13:16:08]

Done.

+  Handle<Map> map =
+      Handle<Map>(masm->isolate()->factory()->fixed_array_map());
+  __ cmp(scratch, Operand(map));
+  __ b(ne, &miss_force_generic);
+
+  // Check that the key is within bounds.
+  if (is_js_array) {
+    __ ldr(scratch, FieldMemOperand(receiver_reg, JSArray::kLengthOffset));
+  } else {
+    __ ldr(scratch, FieldMemOperand(elements_reg, FixedArray::kLengthOffset));
+  }
+  // Compare smis.
+  __ cmp(key_reg, scratch);
+  __ b(hs, &miss_force_generic);
+
+  __ add(scratch,
+         elements_reg, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  ASSERT(kSmiTag == 0 && kSmiTagSize < kPointerSizeLog2);
+  __ str(value_reg,
+         MemOperand(scratch, key_reg, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ RecordWrite(scratch,
+                 Operand(key_reg, LSL, kPointerSizeLog2 - kSmiTagSize),
+                 receiver_reg , elements_reg);
+
+  // value_reg (r0) is preserved.
+  // Done.
+  __ Ret();
+
+  __ bind(&miss_force_generic);
+  Handle<Code> ic =
+      masm->isolate()->builtins()->KeyedStoreIC_MissForceGeneric();
+  __ Jump(ic, RelocInfo::CODE_TARGET);
+}
+
+
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM