[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..8a055a5f5f420bef5f4f363ff0e10db47e18c854 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -722,7 +722,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kArchRet:
-      AssembleReturn();
+      AssembleReturn(instr->InputAt(0));
       break;
     case kArchStackPointer:
       __ mov(i.OutputRegister(), sp);
@@ -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());
+  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);
+    __ dsll(pop_reg, pop_reg, kPointerSizeLog2);
+    __ Daddu(sp, sp, pop_reg);
+  }
   if (pop_count != 0) {
     __ DropAndRet(pop_count);
   } else {