[turbofan] Use switch in ReduceJSCreateArguments

We can make sure we exhaustively test all CreateArgumentsTypes by using
a switch rather than if-else.

Change-Id: Id00094eeb4cb0af212f5c939314aec72a30a3ee0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2128054Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66919}

src/compiler/js-create-lowering.cc

@@ -256,10 +256,12 @@ Reduction JSCreateLowering::ReduceJSCreateArguments(Node* node) {
       }
     }
     UNREACHABLE();
-  } else if (outer_state->opcode() == IrOpcode::kFrameState) {
-    // Use inline allocation for all mapped arguments objects within inlined
-    // (i.e. non-outermost) frames, independent of the object size.
-    if (type == CreateArgumentsType::kMappedArguments) {
+  }
+  // Use inline allocation for all mapped arguments objects within inlined
+  // (i.e. non-outermost) frames, independent of the object size.
+  DCHECK_EQ(outer_state->opcode(), IrOpcode::kFrameState);
+  switch (type) {
+    case CreateArgumentsType::kMappedArguments: {
       Node* const callee = NodeProperties::GetValueInput(node, 0);
       Node* const context = NodeProperties::GetContextInput(node);
       Node* effect = NodeProperties::GetEffectInput(node);
@@ -300,7 +302,8 @@ Reduction JSCreateLowering::ReduceJSCreateArguments(Node* node) {
       RelaxControls(node);
       a.FinishAndChange(node);
       return Changed(node);
-    } else if (type == CreateArgumentsType::kUnmappedArguments) {
+    }
+    case CreateArgumentsType::kUnmappedArguments: {
       // Use inline allocation for all unmapped arguments objects within inlined
       // (i.e. non-outermost) frames, independent of the object size.
       Node* effect = NodeProperties::GetEffectInput(node);
@@ -335,7 +338,8 @@ Reduction JSCreateLowering::ReduceJSCreateArguments(Node* node) {
       RelaxControls(node);
       a.FinishAndChange(node);
       return Changed(node);
-    } else if (type == CreateArgumentsType::kRestParameter) {
+    }
+    case CreateArgumentsType::kRestParameter: {
       int start_index = shared.internal_formal_parameter_count();
       // Use inline allocation for all unmapped arguments objects within inlined
       // (i.e. non-outermost) frames, independent of the object size.
@@ -378,8 +382,7 @@ Reduction JSCreateLowering::ReduceJSCreateArguments(Node* node) {
       return Changed(node);
     }
   }
-
-  return NoChange();
+  UNREACHABLE();
 }
 
 Reduction JSCreateLowering::ReduceJSCreateGeneratorObject(Node* node) {