[arm] Address TODO in CallConstructStub::Generate.

R=jacob.bramley@arm.com

Review URL: https://codereview.chromium.org/1244023002

Cr-Commit-Position: refs/heads/master@{#29774}

src/arm/code-stubs-arm.cc

@@ -2386,17 +2386,20 @@ void RegExpExecStub::Generate(MacroAssembler* masm) {
 
 static void CallStubInRecordCallTarget(MacroAssembler* masm, CodeStub* stub) {
   // r0 : number of arguments to the construct function
-  // r2 : Feedback vector
-  // r3 : slot in feedback vector (Smi)
   // r1 : the function to call
+  // r2 : feedback vector
+  // r3 : slot in feedback vector (Smi)
+  // r4 : original constructor
   FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
 
   // Number-of-arguments register must be smi-tagged to call out.
   __ SmiTag(r0);
   __ Push(r3, r2, r1, r0);
+  __ Push(r4);
 
   __ CallStub(stub);
 
+  __ Pop(r4);
   __ Pop(r3, r2, r1, r0);
   __ SmiUntag(r0);
 }
@@ -2408,8 +2411,9 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
   // megamorphic.
   // r0 : number of arguments to the construct function
   // r1 : the function to call
-  // r2 : Feedback vector
+  // r2 : feedback vector
   // r3 : slot in feedback vector (Smi)
+  // r4 : original constructor
   Label initialize, done, miss, megamorphic, not_array_function;
 
   DCHECK_EQ(*TypeFeedbackVector::MegamorphicSentinel(masm->isolate()),
@@ -2417,23 +2421,23 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
   DCHECK_EQ(*TypeFeedbackVector::UninitializedSentinel(masm->isolate()),
             masm->isolate()->heap()->uninitialized_symbol());
 
-  // Load the cache state into r4.
-  __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
-  __ ldr(r4, FieldMemOperand(r4, FixedArray::kHeaderSize));
+  // Load the cache state into r5.
+  __ add(r5, r2, Operand::PointerOffsetFromSmiKey(r3));
+  __ ldr(r5, FieldMemOperand(r5, FixedArray::kHeaderSize));
 
   // A monomorphic cache hit or an already megamorphic state: invoke the
   // function without changing the state.
-  // We don't know if r4 is a WeakCell or a Symbol, but it's harmless to read at
+  // We don't know if r5 is a WeakCell or a Symbol, but it's harmless to read at
   // this position in a symbol (see static asserts in type-feedback-vector.h).
   Label check_allocation_site;
-  Register feedback_map = r5;
-  Register weak_value = r6;
-  __ ldr(weak_value, FieldMemOperand(r4, WeakCell::kValueOffset));
+  Register feedback_map = r6;
+  Register weak_value = r9;
+  __ ldr(weak_value, FieldMemOperand(r5, WeakCell::kValueOffset));
   __ cmp(r1, weak_value);
   __ b(eq, &done);
-  __ CompareRoot(r4, Heap::kmegamorphic_symbolRootIndex);
+  __ CompareRoot(r5, Heap::kmegamorphic_symbolRootIndex);
   __ b(eq, &done);
-  __ ldr(feedback_map, FieldMemOperand(r4, HeapObject::kMapOffset));
+  __ ldr(feedback_map, FieldMemOperand(r5, HeapObject::kMapOffset));
   __ CompareRoot(feedback_map, Heap::kWeakCellMapRootIndex);
   __ b(ne, FLAG_pretenuring_call_new ? &miss : &check_allocation_site);
 
@@ -2451,8 +2455,8 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
     __ b(ne, &miss);
 
     // Make sure the function is the Array() function
-    __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r4);
-    __ cmp(r1, r4);
+    __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r5);
+    __ cmp(r1, r5);
     __ b(ne, &megamorphic);
     __ jmp(&done);
   }
@@ -2461,14 +2465,14 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
 
   // A monomorphic miss (i.e, here the cache is not uninitialized) goes
   // megamorphic.
-  __ CompareRoot(r4, Heap::kuninitialized_symbolRootIndex);
+  __ CompareRoot(r5, Heap::kuninitialized_symbolRootIndex);
   __ b(eq, &initialize);
   // MegamorphicSentinel is an immortal immovable object (undefined) so no
   // write-barrier is needed.
   __ bind(&megamorphic);
-  __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
+  __ add(r5, r2, Operand::PointerOffsetFromSmiKey(r3));
   __ LoadRoot(ip, Heap::kmegamorphic_symbolRootIndex);
-  __ str(ip, FieldMemOperand(r4, FixedArray::kHeaderSize));
+  __ str(ip, FieldMemOperand(r5, FixedArray::kHeaderSize));
   __ jmp(&done);
 
   // An uninitialized cache is patched with the function
@@ -2476,8 +2480,8 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
 
   if (!FLAG_pretenuring_call_new) {
     // Make sure the function is the Array() function
-    __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r4);
-    __ cmp(r1, r4);
+    __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r5);
+    __ cmp(r1, r5);
     __ b(ne, &not_array_function);
 
     // The target function is the Array constructor,
@@ -2624,14 +2628,7 @@ void CallConstructStub::Generate(MacroAssembler* masm) {
   __ b(ne, &slow);
 
   if (RecordCallTarget()) {
-    if (IsSuperConstructorCall()) {
-      __ push(r4);
-    }
-    // TODO(mstarzinger): Consider tweaking target recording to avoid push/pop.
     GenerateRecordCallTarget(masm);
-    if (IsSuperConstructorCall()) {
-      __ pop(r4);
-    }
 
     __ add(r5, r2, Operand::PointerOffsetFromSmiKey(r3));
     if (FLAG_pretenuring_call_new) {