[turbofan] Support variable size argument popping in TF-generated functions

src/compiler/mips/code-generator-mips.cc

Index: src/compiler/mips/code-generator-mips.cc
diff --git a/src/compiler/mips/code-generator-mips.cc b/src/compiler/mips/code-generator-mips.cc
index 12d3e75a05e193f874cc01e6babdebd79559d731..1648c5270758ccd02d4c1c5c278323809fe3c3cd 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -713,7 +713,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kArchRet:
-      AssembleReturn();
+      AssembleReturn(instr->InputAt(0));
       break;
     case kArchStackPointer:
       __ mov(i.OutputRegister(), sp);
@@ -1964,8 +1964,7 @@ void CodeGenerator::AssembleConstructFrame() {
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int pop_count = static_cast<int>(descriptor->StackParameterCount());
 
@@ -1993,6 +1992,15 @@ void CodeGenerator::AssembleReturn() {
       AssembleDeconstructFrame();
     }
   }
+  MipsOperandConverter g(this, nullptr);
+  if (pop->IsImmediate()) {
+    DCHECK_EQ(Constant::kInt32, g.ToConstant(pop).type());
+    pop_count += g.ToConstant(pop).ToInt32();
+  } else {
+    Register pop_reg = g.ToRegister(pop);
+    __ sll(pop_reg, pop_reg, Operand(kPointerSizeLog2));
+    __ addu(sp, sp, Operand(pop_reg));
+  }
   if (pop_count != 0) {
     __ DropAndRet(pop_count);
   } else {