[compiler] Fallback to slow path for any unexpected opcode in TryGetScopeInfo

The bug is due to an unexpected opcode. To avoid similar issues in the future, we fallback to CheckContextExtensionSlowPath. This was the default behaviour before the CL (https://chromium-review.googlesource.com/c/v8/v8/+/1876051).

Bug: chromium:1020983
Change-Id: Ia7f0f2986ec0008d1128ad3856efbb5d9e52dfc6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1899989
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64794}

src/compiler/bytecode-graph-builder.cc

@@ -1616,14 +1616,8 @@ base::Optional<ScopeInfoRef> BytecodeGraphBuilder::TryGetScopeInfo() {
       }
       return scope_info;
     }
-    case IrOpcode::kJSGeneratorRestoreContext:
-    case IrOpcode::kOsrValue:
-    case IrOpcode::kPhi:
-    // For a large context, the runtime call is still used.
-    case IrOpcode::kJSCallRuntime:
-      return base::nullopt;
     default:
-      UNREACHABLE();
+      return base::nullopt;
   }
 }
 

test/mjsunit/regress/regress-crbug-1020983.js

+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --always-osr
+
+function opt() {
+    for (let i = 0; i < 5000; i++) {
+        try {
+                    try {
+                        throw 1
+                    } finally {
+                        E
+                    }
+        } catch {}
+    }
+eval()
+}
+    opt()