[arm] Address TODO in CallConstructStub::Generate.

src/arm/code-stubs-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 2368 matching lines @@
   __ ldr(r9, FieldMemOperand(subject, SlicedString::kOffsetOffset));
   __ SmiUntag(r9);
   __ ldr(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
   __ jmp(&check_underlying);  // Go to (4).
 #endif  // V8_INTERPRETED_REGEXP
 }
 
 
 static void CallStubInRecordCallTarget(MacroAssembler* masm, CodeStub* stub) {
   // r0 : number of arguments to the construct function
-  // r2 : Feedback vector
+  // r1 : the function to call
+  // r2 : feedback vector
   // r3 : slot in feedback vector (Smi)
-  // r1 : the function to call
+  // 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);

[Michael Starzinger, 2015/07/21 13:22:26]

Please don't make me implement the Push() variant with 5 registers. :)

[jbramley, 2015/07/21 13:28:02]

It doesn't matter quite as much for ARM anyway, since it doesn't have the
per-push sp update overhead.

 
   __ CallStub(stub);
 
+  __ Pop(r4);
   __ Pop(r3, r2, r1, r0);
   __ SmiUntag(r0);
 }
 
 
 static void GenerateRecordCallTarget(MacroAssembler* masm) {
   // Cache the called function in a feedback vector slot.  Cache states
   // are uninitialized, monomorphic (indicated by a JSFunction), and
   // 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()),
             masm->isolate()->heap()->megamorphic_symbol());
   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);
 
   // If the weak cell is cleared, we have a new chance to become monomorphic.
   __ JumpIfSmi(weak_value, &initialize);
   __ jmp(&megamorphic);
 
   if (!FLAG_pretenuring_call_new) {
     __ bind(&check_allocation_site);
     // If we came here, we need to see if we are the array function.
     // If we didn't have a matching function, and we didn't find the megamorph
     // sentinel, then we have in the slot either some other function or an
     // AllocationSite.
     __ CompareRoot(feedback_map, Heap::kAllocationSiteMapRootIndex);
     __ 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);
   }
 
   __ bind(&miss);
 
   // 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
   __ bind(&initialize);
 
   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,
     // Create an AllocationSite if we don't already have it, store it in the
     // slot.
     CreateAllocationSiteStub create_stub(masm->isolate());
     CallStubInRecordCallTarget(masm, &create_stub);
     __ b(&done);
 
     __ bind(&not_array_function);
@@ skipping 126 matching lines @@
   // r4 : original constructor (for IsSuperConstructorCall)
   Label slow, non_function_call;
 
   // Check that the function is not a smi.
   __ JumpIfSmi(r1, &non_function_call);
   // Check that the function is a JSFunction.
   __ CompareObjectType(r1, r5, r5, JS_FUNCTION_TYPE);
   __ 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) {
       // Put the AllocationSite from the feedback vector into r2.
       // By adding kPointerSize we encode that we know the AllocationSite
       // entry is at the feedback vector slot given by r3 + 1.
       __ ldr(r2, FieldMemOperand(r5, FixedArray::kHeaderSize + kPointerSize));
     } else {
       Label feedback_register_initialized;
       // Put the AllocationSite from the feedback vector into r2, or undefined.
@@ skipping 2731 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM