From b034a909a624036f7da1bd16136aa41b8fadcf4b Mon Sep 17 00:00:00 2001
From: Mayank Patke <fishythefish@google.com>
Date: Mon, 30 Oct 2023 22:08:47 +0000
Subject: [PATCH] [dart2js] Avoid discarding type tests during SSA with
 --experiment-null-safety-checks

Change-Id: If3e2465103494d4772b1f8b71e7c57ae83b3e036
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/332371
Commit-Queue: Mayank Patke <fishythefish@google.com>
Reviewed-by: Nate Biggs <natebiggs@google.com>
---
 pkg/compiler/lib/src/ssa/nodes.dart | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkg/compiler/lib/src/ssa/nodes.dart b/pkg/compiler/lib/src/ssa/nodes.dart
index 302b22c54f2..21488aa6fc2 100644
--- a/pkg/compiler/lib/src/ssa/nodes.dart
+++ b/pkg/compiler/lib/src/ssa/nodes.dart
@@ -4343,6 +4343,10 @@ AbstractBool _typeTest(
     JClosedWorld closedWorld,
     CompilerOptions options,
     {required bool isCast}) {
+  // The null safety mode may affect the result of a type test, so defer to
+  // runtime.
+  if (options.experimentNullSafetyChecks) return AbstractBool.Maybe;
+
   JCommonElements commonElements = closedWorld.commonElements;
   DartTypes dartTypes = closedWorld.dartTypes;
   AbstractValueDomain abstractValueDomain = closedWorld.abstractValueDomain;