[regexp] Allow empty ranges in GetQuickCheckDetails

A follow-up to crrev.com/c/3240782.

Drive-by: extend JSRegExp printing.

Fixed: chromium:1263327
Bug: v8:11069
Change-Id: Iff64ded27ca93641f0f572df2ce0a9f846948f7f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3245110
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77536}

src/diagnostics/objects-printer.cc

@@ -688,9 +688,11 @@ void JSPromise::JSPromisePrint(std::ostream& os) {
 }
 
 void JSRegExp::JSRegExpPrint(std::ostream& os) {
+  Isolate* isolate = GetIsolate();
   JSObjectPrintHeader(os, *this, "JSRegExp");
   os << "\n - data: " << Brief(data());
   os << "\n - source: " << Brief(source());
+  os << "\n - flags: " << Brief(*JSRegExp::StringFromFlags(isolate, flags()));
   JSObjectPrintBody(os, *this);
 }
 

src/regexp/regexp-compiler.cc

@@ -1669,12 +1669,14 @@ void TextNode::GetQuickCheckDetails(QuickCheckDetails* details,
           details->positions(characters_filled_in);
       RegExpCharacterClass* tree = elm.char_class();
       ZoneList<CharacterRange>* ranges = tree->ranges(zone());
-      DCHECK(!ranges->is_empty());
-      if (tree->is_negated()) {
+      if (tree->is_negated() || ranges->is_empty()) {
         // A quick check uses multi-character mask and compare.  There is no
         // useful way to incorporate a negative char class into this scheme
         // so we just conservatively create a mask and value that will always
         // succeed.
+        // Likewise for empty ranges (empty ranges can occur e.g. when
+        // compiling for one-byte subjects and impossible (non-one-byte) ranges
+        // have been removed).
         pos->mask = 0;
         pos->value = 0;
       } else {

test/mjsunit/regress/regress-1263327.js

+// Copyright 2021 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.
+
+assertNull(/.?\ud833{6,}/gsu.exec());