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

src/compiler/mips64/code-generator-mips64.cc

Index: src/compiler/mips64/code-generator-mips64.cc
diff --git a/src/compiler/mips64/code-generator-mips64.cc b/src/compiler/mips64/code-generator-mips64.cc
index 01d7f5d8d9fa5d593aedd5a664478d4d60c9f899..aeee70af04f94a369a2a83e6de1d9fed4028db02 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -2281,8 +2281,7 @@ void CodeGenerator::AssembleConstructFrame() {
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
 
   // Restore GP registers.
@@ -2310,6 +2309,15 @@ void CodeGenerator::AssembleReturn() {
     }
   }
   int pop_count = static_cast<int>(descriptor->StackParameterCount());
+  Mips64OperandConverter 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 {