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

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

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index e969f02e1f5dfeb727118057fcdbb4162b1e7e22..17fe8cdb0fad4b7affa3976fe6e9ece6dfd327f7 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -759,7 +759,7 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kArchRet:
-      AssembleReturn();
+      AssembleReturn(instr->InputAt(0));
       DCHECK_EQ(LeaveCC, i.OutputSBit());
       break;
     case kArchStackPointer:
@@ -1752,8 +1752,7 @@ void CodeGenerator::AssembleConstructFrame() {
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int pop_count = static_cast<int>(descriptor->StackParameterCount());
 
@@ -1789,7 +1788,16 @@ void CodeGenerator::AssembleReturn() {
       AssembleDeconstructFrame();
     }
   }
-  __ Ret(pop_count);
+
+  ArmOperandConverter g(this, nullptr);
+  if (pop->IsImmediate()) {
+    DCHECK_EQ(Constant::kInt32, g.ToConstant(pop).type());
+    pop_count += g.ToConstant(pop).ToInt32();
+  } else {
+    __ Drop(g.ToRegister(pop));
+  }
+  __ Drop(pop_count);
+  __ Ret();
 }