[fullcode] Switch passing of new.target to register.

src/full-codegen/mips/full-codegen-mips.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.
 
 #if V8_TARGET_ARCH_MIPS
 
 // Note on Mips implementation:
 //
 // The result_register() for mips is the 'v0' register, which is defined
 // by the ABI to contain function return values. However, the first
@@ skipping 83 matching lines @@
 };
 
 
 // Generate code for a JS function.  On entry to the function the receiver
 // and arguments have been pushed on the stack left to right.  The actual
 // argument count matches the formal parameter count expected by the
 // function.
 //
 // The live registers are:
 //   o a1: the JS function object being called (i.e. ourselves)
+//   o a3: the new target value
 //   o cp: our context
 //   o fp: our caller's frame pointer
 //   o sp: stack pointer
 //   o ra: return address
 //
 // The function builds a JS frame.  Please see JavaScriptFrameConstants in
 // frames-mips.h for its layout.
 void FullCodeGenerator::Generate() {
   CompilationInfo* info = info_;
   profiling_counter_ = isolate()->factory()->NewCell(
@@ skipping 71 matching lines @@
   if (info->scope()->num_heap_slots() > 0) {
     Comment cmnt(masm_, "[ Allocate context");
     // Argument to NewContext is the function, which is still in a1.
     bool need_write_barrier = true;
     int slots = info->scope()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
     if (info->scope()->is_script_scope()) {
       __ push(a1);
       __ Push(info->scope()->GetScopeInfo(info->isolate()));
       __ CallRuntime(Runtime::kNewScriptContext, 2);
       PrepareForBailoutForId(BailoutId::ScriptContext(), TOS_REG);
-    } else if (slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(isolate(), slots);
-      __ CallStub(&stub);
-      // Result of FastNewContextStub is always in new space.
-      need_write_barrier = false;
+      // The new target value is not used, clobbering is safe.
+      DCHECK_NULL(info->scope()->new_target_var());
     } else {
-      __ push(a1);
-      __ CallRuntime(Runtime::kNewFunctionContext, 1);
+      if (info->scope()->new_target_var() != nullptr) {
+        __ push(a3);  // Preserve new target.
+      }
+      if (slots <= FastNewContextStub::kMaximumSlots) {
+        FastNewContextStub stub(isolate(), slots);
+        __ CallStub(&stub);
+        // Result of FastNewContextStub is always in new space.
+        need_write_barrier = false;
+      } else {
+        __ push(a1);
+        __ CallRuntime(Runtime::kNewFunctionContext, 1);
+      }
+      if (info->scope()->new_target_var() != nullptr) {
+        __ pop(a3);  // Restore new target.
+      }
     }
     function_in_register_a1 = false;
     // Context is returned in v0. It replaces the context passed to us.
     // It's saved in the stack and kept live in cp.
     __ mov(cp, v0);
     __ sw(v0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
     int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
     for (int i = first_parameter; i < num_parameters; i++) {
       Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
                                  (num_parameters - 1 - i) * kPointerSize;
         // Load parameter from stack.
         __ lw(a0, MemOperand(fp, parameter_offset));
         // Store it in the context.
         MemOperand target = ContextMemOperand(cp, var->index());
         __ sw(a0, target);
 
         // Update the write barrier.
         if (need_write_barrier) {
-          __ RecordWriteContextSlot(
-              cp, target.offset(), a0, a3, kRAHasBeenSaved, kDontSaveFPRegs);
+          __ RecordWriteContextSlot(cp, target.offset(), a0, a2,
+                                    kRAHasBeenSaved, kDontSaveFPRegs);
         } else if (FLAG_debug_code) {
           Label done;
           __ JumpIfInNewSpace(cp, a0, &done);
           __ Abort(kExpectedNewSpaceObject);
           __ bind(&done);
         }
       }
     }
   }
+
+  // Register holding this function and new target are both trashed in case we
+  // bailout here. But since that can happen only when new target is not used
+  // and we allocate a context, the value of |function_in_register| is correct.
   PrepareForBailoutForId(BailoutId::FunctionContext(), NO_REGISTERS);
 
-  // Function register is trashed in case we bailout here. But since that
-  // could happen only when we allocate a context the value of
-  // |function_in_register_a1| is correct.
-
   // Possibly set up a local binding to the this function which is used in
   // derived constructors with super calls.
   Variable* this_function_var = scope()->this_function_var();
   if (this_function_var != nullptr) {
     Comment cmnt(masm_, "[ This function");
     if (!function_in_register_a1) {
       __ lw(a1, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
       // The write barrier clobbers register again, keep it marked as such.
     }
-    SetVar(this_function_var, a1, a2, a3);
+    SetVar(this_function_var, a1, a0, a2);
   }
 
+  // Possibly set up a local binding to the new target value.
   Variable* new_target_var = scope()->new_target_var();
   if (new_target_var != nullptr) {
     Comment cmnt(masm_, "[ new.target");
-
-    // Get the frame pointer for the calling frame.
-    __ lw(a2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
-
-    // Skip the arguments adaptor frame if it exists.
-    Label check_frame_marker;
-    __ lw(a1, MemOperand(a2, StandardFrameConstants::kContextOffset));
-    __ Branch(&check_frame_marker, ne, a1,
-              Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
-    __ lw(a2, MemOperand(a2, StandardFrameConstants::kCallerFPOffset));
-
-    // Check the marker in the calling frame.
-    __ bind(&check_frame_marker);
-    __ lw(a1, MemOperand(a2, StandardFrameConstants::kMarkerOffset));
-    function_in_register_a1 = false;
-
-    Label non_construct_frame, done;
-    __ Branch(&non_construct_frame, ne, a1,
-              Operand(Smi::FromInt(StackFrame::CONSTRUCT)));
-
-    __ lw(v0, MemOperand(a2, ConstructFrameConstants::kNewTargetOffset));
-    __ Branch(&done);
-
-    __ bind(&non_construct_frame);
-    __ LoadRoot(v0, Heap::kUndefinedValueRootIndex);
-    __ bind(&done);
-
-    SetVar(new_target_var, v0, a2, a3);
+    SetVar(new_target_var, a3, a0, a2);
   }
 
   Variable* arguments = scope()->arguments();
   if (arguments != NULL) {
     // Function uses arguments object.
     Comment cmnt(masm_, "[ Allocate arguments object");
     DCHECK(a1.is(ArgumentsAccessNewDescriptor::function()));
     if (!function_in_register_a1) {
       // Load this again, if it's used by the local context below.
       __ lw(a1, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
@@ skipping 4643 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS