[fullcodegen] Avoid arguments juggling when calling a JS runtime function.

src/full-codegen/s390/full-codegen-s390.cc

 // Copyright 2015 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_S390
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3239 matching lines @@
   __ b(&done);
 
   __ bind(&runtime);
   CallRuntimeWithOperands(Runtime::kCreateIterResultObject);
 
   __ bind(&done);
   context()->Plug(r2);
 }
 
 void FullCodeGenerator::EmitLoadJSRuntimeFunction(CallRuntime* expr) {
+  // Push function.
+  __ LoadNativeContextSlot(expr->context_index(), r2);
+  PushOperand(r2);
+
   // Push undefined as the receiver.
   __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
   PushOperand(r2);
-
-  __ LoadNativeContextSlot(expr->context_index(), r2);
 }
 
 void FullCodeGenerator::EmitCallJSRuntimeFunction(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
 
   SetCallPosition(expr);
   __ LoadP(r3, MemOperand(sp, (arg_count + 1) * kPointerSize), r0);
   __ mov(r2, Operand(arg_count));
   __ Call(isolate()->builtins()->Call(ConvertReceiverMode::kNullOrUndefined),
           RelocInfo::CODE_TARGET);
   OperandStackDepthDecrement(arg_count + 1);
 }
 
 void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
 
   if (expr->is_jsruntime()) {
     Comment cmnt(masm_, "[ CallRuntime");
     EmitLoadJSRuntimeFunction(expr);
 
-    // Push the target function under the receiver.
-    __ LoadP(ip, MemOperand(sp, 0));
-    PushOperand(ip);
-    __ StoreP(r2, MemOperand(sp, kPointerSize));
-
     // Push the arguments ("left-to-right").
     for (int i = 0; i < arg_count; i++) {
       VisitForStackValue(args->at(i));
     }
 
     PrepareForBailoutForId(expr->CallId(), NO_REGISTERS);
     EmitCallJSRuntimeFunction(expr);
 
     // Restore context register.
     __ LoadP(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
@@ skipping 730 matching lines @@
   DCHECK(kOSRBranchInstruction == br_instr);
 
   DCHECK(interrupt_address ==
          isolate->builtins()->OnStackReplacement()->entry());
   return ON_STACK_REPLACEMENT;
 }
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_TARGET_ARCH_S390