PPC/S390: Fix to skip processing args if count zero

This issue was exposed with this CL
https://chromium-review.googlesource.com/c/v8/v8/+/654257

R=joransiu@ca.ibm.com, jyan@ca.ibm.com
BUG=
LOG=N

Change-Id: I216bfc8079bf62a58f8e6c20d4ac9d22bc445b51
Reviewed-on: https://chromium-review.googlesource.com/656306Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Jaideep Bajwa <bjaideep@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#47907}

src/builtins/ppc/builtins-ppc.cc

@@ -1360,13 +1360,16 @@ static void Generate_StackOverflowCheck(MacroAssembler* masm, Register num_args,
 static void Generate_InterpreterPushArgs(MacroAssembler* masm,
                                          Register num_args, Register index,
                                          Register count, Register scratch) {
-  Label loop;
+  Label loop, skip;
+  __ cmpi(count, Operand::Zero());
+  __ beq(&skip);
   __ addi(index, index, Operand(kPointerSize));  // Bias up for LoadPU
   __ mtctr(count);
   __ bind(&loop);
   __ LoadPU(scratch, MemOperand(index, -kPointerSize));
   __ push(scratch);
   __ bdnz(&loop);
+  __ bind(&skip);
 }
 
 // static

src/builtins/s390/builtins-s390.cc

@@ -1356,7 +1356,9 @@ static void Generate_StackOverflowCheck(MacroAssembler* masm, Register num_args,
 static void Generate_InterpreterPushArgs(MacroAssembler* masm,
                                          Register num_args, Register index,
                                          Register count, Register scratch) {
-  Label loop;
+  Label loop, skip;
+  __ CmpP(count, Operand::Zero());
+  __ beq(&skip);
   __ AddP(index, index, Operand(kPointerSize));  // Bias up for LoadPU
   __ LoadRR(r0, count);
   __ bind(&loop);
@@ -1365,6 +1367,7 @@ static void Generate_InterpreterPushArgs(MacroAssembler* masm,
   __ push(scratch);
   __ SubP(r0, Operand(1));
   __ bne(&loop);
+  __ bind(&skip);
 }
 
 // static