PPC: Do not add extra argument for new.target

Port 8196c28a

Original commit message:
JSConstructStub for subclass constructors instead locates new.target in
a known location on the stack.

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

Review URL: https://codereview.chromium.org/1208443002

Cr-Commit-Position: refs/heads/master@{#29254}

src/ppc/builtins-ppc.cc

@@ -788,8 +788,6 @@ void Builtins::Generate_JSConstructStubForDerived(MacroAssembler* masm) {
     __ bdnz(&loop);
     __ bind(&no_args);
 
-    __ addi(r3, r3, Operand(1));
-
     // Handle step in.
     Label skip_step_in;
     ExternalReference debug_step_in_fp =
@@ -815,7 +813,8 @@ void Builtins::Generate_JSConstructStubForDerived(MacroAssembler* masm) {
     // r3: result
     // sp[0]: number of arguments (smi-tagged)
     __ LoadP(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
-    __ LoadP(r4, MemOperand(sp, 0));
+    // Get arguments count, skipping over new.target.
+    __ LoadP(r4, MemOperand(sp, kPointerSize));
 
     // Leave construct frame.
   }

src/ppc/code-stubs-ppc.cc

@@ -1628,7 +1628,6 @@ void LoadIndexedStringStub::Generate(MacroAssembler* masm) {
 
 
 void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
-  CHECK(!has_new_target());
   // The displacement is the offset of the last parameter (if any)
   // relative to the frame pointer.
   const int kDisplacement =
@@ -1689,8 +1688,6 @@ void ArgumentsAccessStub::GenerateNewSloppySlow(MacroAssembler* masm) {
   // sp[1] : receiver displacement
   // sp[2] : function
 
-  CHECK(!has_new_target());
-
   // Check if the calling frame is an arguments adaptor frame.
   Label runtime;
   __ LoadP(r6, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
@@ -1721,8 +1718,6 @@ void ArgumentsAccessStub::GenerateNewSloppyFast(MacroAssembler* masm) {
   //  r9 : allocated object (tagged)
   //  r11 : mapped parameter count (tagged)
 
-  CHECK(!has_new_target());
-
   __ LoadP(r4, MemOperand(sp, 0 * kPointerSize));
   // r4 = parameter count (tagged)
 
@@ -2005,14 +2000,6 @@ void ArgumentsAccessStub::GenerateNewStrict(MacroAssembler* masm) {
   // Patch the arguments.length and the parameters pointer.
   __ bind(&adaptor_frame);
   __ LoadP(r4, MemOperand(r5, ArgumentsAdaptorFrameConstants::kLengthOffset));
-  if (has_new_target()) {
-    __ CmpSmiLiteral(r4, Smi::FromInt(0), r0);
-    Label skip_decrement;
-    __ beq(&skip_decrement);
-    // Subtract 1 from smi-tagged arguments count.
-    __ SubSmiLiteral(r4, r4, Smi::FromInt(1), r0);
-    __ bind(&skip_decrement);
-  }
   __ StoreP(r4, MemOperand(sp, 0));
   __ SmiToPtrArrayOffset(r6, r4);
   __ add(r6, r5, r6);

src/ppc/full-codegen-ppc.cc

@@ -254,18 +254,35 @@ void FullCodeGenerator::Generate() {
   Variable* new_target_var = scope()->new_target_var();
   if (new_target_var != nullptr) {
     Comment cmnt(masm_, "[ new.target");
-    // new.target is parameter -2.
-    int offset = 2 * kPointerSize +
-                 (info_->scope()->num_parameters() + 1) * kPointerSize;
-    __ LoadP(r3, MemOperand(fp, offset));
+
+    // Get the frame pointer for the calling frame.
+    __ LoadP(r5, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
+
+    // Skip the arguments adaptor frame if it exists.
+    __ LoadP(r4, MemOperand(r5, StandardFrameConstants::kContextOffset));
+    __ CmpSmiLiteral(r4, Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR), r0);
+    Label skip;
+    __ bne(&skip);
+    __ LoadP(r5, MemOperand(r5, StandardFrameConstants::kCallerFPOffset));
+    __ bind(&skip);
+
+    // Check the marker in the calling frame.
+    __ LoadP(r4, MemOperand(r5, StandardFrameConstants::kMarkerOffset));
+    __ CmpSmiLiteral(r4, Smi::FromInt(StackFrame::CONSTRUCT), r0);
+    Label non_construct_frame, done;
+
+    __ bne(&non_construct_frame);
+    __ LoadP(r3, MemOperand(r5, StandardFrameConstants::kExpressionsOffset -
+                                    2 * kPointerSize));
+    __ b(&done);
+
+    __ bind(&non_construct_frame);
+    __ LoadRoot(r3, Heap::kUndefinedValueRootIndex);
+    __ bind(&done);
+
     SetVar(new_target_var, r3, r5, r6);
   }
 
-  ArgumentsAccessStub::HasNewTarget has_new_target =
-      IsSubclassConstructor(info->function()->kind())
-          ? ArgumentsAccessStub::HAS_NEW_TARGET
-          : ArgumentsAccessStub::NO_NEW_TARGET;
-
   // Possibly allocate RestParameters
   int rest_index;
   Variable* rest_param = scope()->rest_parameter(&rest_index);
@@ -274,10 +291,6 @@ void FullCodeGenerator::Generate() {
 
     int num_parameters = info->scope()->num_parameters();
     int offset = num_parameters * kPointerSize;
-    if (has_new_target == ArgumentsAccessStub::HAS_NEW_TARGET) {
-      --num_parameters;
-      ++rest_index;
-    }
 
     __ addi(r6, fp, Operand(StandardFrameConstants::kCallerSPOffset + offset));
     __ LoadSmiLiteral(r5, Smi::FromInt(num_parameters));
@@ -320,7 +333,7 @@ void FullCodeGenerator::Generate() {
     } else {
       type = ArgumentsAccessStub::NEW_SLOPPY_FAST;
     }
-    ArgumentsAccessStub stub(isolate(), type, has_new_target);
+    ArgumentsAccessStub stub(isolate(), type);
     __ CallStub(&stub);
 
     SetVar(arguments, r3, r4, r5);
@@ -484,9 +497,6 @@ void FullCodeGenerator::EmitReturnSequence() {
     {
       Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm_);
       int32_t arg_count = info_->scope()->num_parameters() + 1;
-      if (IsSubclassConstructor(info_->function()->kind())) {
-        arg_count++;
-      }
       int32_t sp_delta = arg_count * kPointerSize;
       CodeGenerator::RecordPositions(masm_, function()->end_position() - 1);
       __ RecordJSReturn();
@@ -4286,9 +4296,6 @@ void FullCodeGenerator::EmitDefaultConstructorCallSuper(CallRuntime* expr) {
     __ LoadP(r3, MemOperand(r5, ArgumentsAdaptorFrameConstants::kLengthOffset));
     __ SmiUntag(r3);
 
-    // Subtract 1 from arguments count, for new.target.
-    __ subi(r3, r3, Operand(1));
-
     // Get arguments pointer in r5.
     __ ShiftLeftImm(r0, r3, Operand(kPointerSizeLog2));
     __ add(r5, r5, r0);