PPC: Cleanup Generate_JSConstructStubHelper a bit.

Port 6ddcd327

R=mstarzinger@chromium.org, dstence@us.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1234953002

Cr-Commit-Position: refs/heads/master@{#29623}

src/ppc/builtins-ppc.cc

@@ -307,34 +307,6 @@ void Builtins::Generate_InOptimizationQueue(MacroAssembler* masm) {
 }
 
 
-static void Generate_Runtime_NewObject(MacroAssembler* masm,
-                                       bool create_memento,
-                                       Register original_constructor,
-                                       Label* count_incremented,
-                                       Label* allocated) {
-  // ----------- S t a t e -------------
-  //  -- r4: argument for Runtime_NewObject
-  // -----------------------------------
-  Register result = r7;
-
-  if (create_memento) {
-    // Get the cell or allocation site.
-    __ LoadP(r5, MemOperand(sp, 3 * kPointerSize));
-    __ Push(r5, r4, original_constructor);
-    __ CallRuntime(Runtime::kNewObjectWithAllocationSite, 3);
-    __ mr(result, r3);
-    // Runtime_NewObjectWithAllocationSite increments allocation count.
-    // Skip the increment.
-    __ b(count_incremented);
-  } else {
-    __ Push(r4, original_constructor);
-    __ CallRuntime(Runtime::kNewObject, 2);
-    __ mr(result, r3);
-    __ b(allocated);
-  }
-}
-
-
 static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                            bool is_api_function,
                                            bool create_memento) {
@@ -365,17 +337,9 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
     __ SmiTag(r3);
     __ Push(r3, r4, r6);
 
-    Label rt_call, allocated, normal_new, count_incremented;
-    __ cmp(r4, r6);
-    __ beq(&normal_new);
-
-    // Original constructor and function are different.
-    Generate_Runtime_NewObject(masm, create_memento, r6, &count_incremented,
-                               &allocated);
-    __ bind(&normal_new);
-
     // Try to allocate the object without transitioning into C code. If any of
     // the preconditions is not met, the code bails out to the runtime call.
+    Label rt_call, allocated;
     if (FLAG_inline_new) {
       ExternalReference debug_step_in_fp =
           ExternalReference::debug_step_in_fp_address(isolate);
@@ -384,12 +348,16 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
       __ cmpi(r5, Operand::Zero());
       __ bne(&rt_call);
 
+      // Fall back to runtime if the original constructor and function differ.
+      __ cmp(r4, r6);
+      __ bne(&rt_call);
+
       // Load the initial map and verify that it is in fact a map.
       // r4: constructor function
       __ LoadP(r5,
                FieldMemOperand(r4, JSFunction::kPrototypeOrInitialMapOffset));
       __ JumpIfSmi(r5, &rt_call);
-      __ CompareObjectType(r5, r6, r7, MAP_TYPE);
+      __ CompareObjectType(r5, r8, r7, MAP_TYPE);
       __ bne(&rt_call);
 
       // Check that the constructor is not constructing a JSFunction (see
@@ -397,7 +365,7 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
       // initial map's instance type would be JS_FUNCTION_TYPE.
       // r4: constructor function
       // r5: initial map
-      __ CompareInstanceType(r5, r6, JS_FUNCTION_TYPE);
+      __ CompareInstanceType(r5, r8, JS_FUNCTION_TYPE);
       __ beq(&rt_call);
 
       if (!is_api_function) {
@@ -427,12 +395,13 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
       // Now allocate the JSObject on the heap.
       // r4: constructor function
       // r5: initial map
+      Label rt_call_reload_new_target;
       __ lbz(r6, FieldMemOperand(r5, Map::kInstanceSizeOffset));
       if (create_memento) {
         __ addi(r6, r6, Operand(AllocationMemento::kSize / kPointerSize));
       }
 
-      __ Allocate(r6, r7, r8, r9, &rt_call, SIZE_IN_WORDS);
+      __ Allocate(r6, r7, r8, r9, &rt_call_reload_new_target, SIZE_IN_WORDS);
 
       // Allocated the JSObject, now initialize the fields. Map is set to
       // initial map and properties and elements are set to empty fixed array.
@@ -517,13 +486,33 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
       // Continue with JSObject being successfully allocated
       // r7: JSObject
       __ b(&allocated);
+
+      // Reload the original constructor and fall-through.
+      __ bind(&rt_call_reload_new_target);
+      __ LoadP(r6, MemOperand(sp, 0 * kPointerSize));
     }
 
     // Allocate the new receiver object using the runtime call.
     // r4: constructor function
+    // r6: original constructor
     __ bind(&rt_call);
-    Generate_Runtime_NewObject(masm, create_memento, r4, &count_incremented,
-                               &allocated);
+    if (create_memento) {
+      // Get the cell or allocation site.
+      __ LoadP(r5, MemOperand(sp, 3 * kPointerSize));
+      __ Push(r5, r4, r6);
+      __ CallRuntime(Runtime::kNewObjectWithAllocationSite, 3);
+    } else {
+      __ Push(r4, r6);
+      __ CallRuntime(Runtime::kNewObject, 2);
+    }
+    __ mr(r7, r3);
+
+    // Runtime_NewObjectWithAllocationSite increments allocation count.
+    // Skip the increment.
+    Label count_incremented;
+    if (create_memento) {
+      __ b(&count_incremented);
+    }
 
     // Receiver for constructor call allocated.
     // r7: JSObject
@@ -610,7 +599,7 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
 
     // If the result is a smi, it is *not* an object in the ECMA sense.
     // r3: result
-    // sp[0]: receiver (newly allocated object)
+    // sp[0]: receiver
     // sp[1]: new.target
     // sp[2]: number of arguments (smi-tagged)
     __ JumpIfSmi(r3, &use_receiver);