[regexp] Add UseCounter for invalid regexp with /v, but valid with /u

Some patterns that were valid with /u are invalid with /v.
This CL adds a UseCounter for such usages in /u to get an idea how often
they are used in the wild.
This is important information w.r.t the proposal to use /v instead of /u
for the pattern attribute (http://go/gh/whatwg/html/pull/7908).

Chromium CL: https://crrev.com/c/4221395

Bug: v8:11935
Change-Id: Idc023ceba9ce03eee578d6c387ce8a8f37db292f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4212393
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85639}

include/v8-isolate.h

@@ -538,6 +538,7 @@ class V8_EXPORT Isolate {
     kAsyncStackTaggingCreateTaskCall = 116,
     kDurationFormat = 117,
     kInvalidatedNumberStringPrototypeNoReplaceProtector = 118,
+    kRegExpUnicodeSetIncompatibilitiesWithUnicodeMode = 119,
 
     // If you add new values here, you'll also need to update Chromium's:
     // web_feature.mojom, use_counter_callback.cc, and enums.xml. V8 changes to

src/regexp/regexp-parser.cc

@@ -429,8 +429,8 @@ class RegExpParserState : public ZoneObject {
 template <class CharT>
 class RegExpParserImpl final {
  private:
-  RegExpParserImpl(const CharT* input, int input_length, RegExpFlags flags,
-                   uintptr_t stack_limit, Zone* zone,
+  RegExpParserImpl(Isolate* isolate, const CharT* input, int input_length,
+                   RegExpFlags flags, uintptr_t stack_limit, Zone* zone,
                    const DisallowGarbageCollection& no_gc);
 
   bool Parse(RegExpCompileData* result);
@@ -563,6 +563,7 @@ class RegExpParserImpl final {
   bool HasNamedCaptures(InClassEscapeState in_class_escape_state);
 
   Zone* zone() const { return zone_; }
+  Isolate* isolate() const { return isolate_; }
 
   base::uc32 current() const { return current_; }
   bool has_more() const { return has_more_; }
@@ -603,6 +604,10 @@ class RegExpParserImpl final {
 
   const DisallowGarbageCollection no_gc_;
   Zone* const zone_;
+  // TODO(pthier, v8:11935): Isolate is only used to increment the UseCounter
+  // for unicode set incompabilities in unicode mode. Remove when the counter
+  // is removed.
+  Isolate* const isolate_;
   RegExpError error_ = RegExpError::kNone;
   int error_pos_ = 0;
   ZoneList<RegExpCapture*>* captures_;
@@ -629,9 +634,10 @@ class RegExpParserImpl final {
 
 template <class CharT>
 RegExpParserImpl<CharT>::RegExpParserImpl(
-    const CharT* input, int input_length, RegExpFlags flags,
+    Isolate* isolate, const CharT* input, int input_length, RegExpFlags flags,
     uintptr_t stack_limit, Zone* zone, const DisallowGarbageCollection& no_gc)
     : zone_(zone),
+      isolate_(isolate),
       captures_(nullptr),
       named_captures_(nullptr),
       named_back_references_(nullptr),
@@ -2417,6 +2423,21 @@ void RegExpParserImpl<CharT>::ParseClassEscape(
   if (current() != '\\') {
     // Not a ClassEscape.
     *char_out = current();
+    // Count usages of patterns that would break when replacing /u with /v.
+    // This is only temporarily enabled and should give us an idea if it is
+    // feasible to enable unicode sets for usage in the pattern attribute.
+    // TODO(pthier, v8:11935): Remove for M113.
+    // IsUnicodeMode() is true for both /u and /v, but this method is only
+    // called for /u.
+    if (IsUnicodeMode() && isolate() != nullptr) {
+      const bool unicode_sets_invalid =
+          IsClassSetSyntaxCharacter(*char_out) ||
+          IsClassSetReservedDoublePunctuator(*char_out);
+      if (unicode_sets_invalid) {
+        isolate()->CountUsage(
+            v8::Isolate::kRegExpUnicodeSetIncompatibilitiesWithUnicodeMode);
+      }
+    }
     Advance();
     return;
   }
@@ -3113,13 +3134,13 @@ bool RegExpParser::ParseRegExpFromHeapString(Isolate* isolate, Zone* zone,
   String::FlatContent content = input->GetFlatContent(no_gc);
   if (content.IsOneByte()) {
     base::Vector<const uint8_t> v = content.ToOneByteVector();
-    return RegExpParserImpl<uint8_t>{v.begin(),   v.length(), flags,
+    return RegExpParserImpl<uint8_t>{isolate,     v.begin(), v.length(), flags,
                                      stack_limit, zone,      no_gc}
         .Parse(result);
   } else {
     base::Vector<const base::uc16> v = content.ToUC16Vector();
-    return RegExpParserImpl<base::uc16>{v.begin(),   v.length(), flags,
-                                        stack_limit, zone,       no_gc}
+    return RegExpParserImpl<base::uc16>{
+        isolate, v.begin(), v.length(), flags, stack_limit, zone, no_gc}
         .Parse(result);
   }
 }
@@ -3131,7 +3152,13 @@ bool RegExpParser::VerifyRegExpSyntax(Zone* zone, uintptr_t stack_limit,
                                       RegExpFlags flags,
                                       RegExpCompileData* result,
                                       const DisallowGarbageCollection& no_gc) {
-  return RegExpParserImpl<CharT>{input,       input_length, flags,
+  // TODO(pthier, v8:11935): Isolate is only temporarily used to increment the
+  // UseCounter for unicode set incompabilities in unicode mode.
+  // This method is only used in the parser for early-errors. To avoid passing
+  // the isolate through we simply pass a nullptr. This also has the positive
+  // side-effect of not incrementing the UseCounter multiple times.
+  Isolate* isolate = nullptr;
+  return RegExpParserImpl<CharT>{isolate,     input, input_length, flags,
                                  stack_limit, zone,  no_gc}
       .Parse(result);
 }

test/unittests/regexp/regexp-unittest.cc

@@ -1654,6 +1654,42 @@ void MockUseCounterCallback(v8::Isolate* isolate,
                             v8::Isolate::UseCounterFeature feature) {
   ++global_use_counts[feature];
 }
+
+void CheckRegExpUnicodeSetIncompatibilitiesUseCounter(
+    v8::Isolate* isolate, const char* check_pattern) {
+  int* use_counts = global_use_counts;
+  int old_count = use_counts
+      [v8::Isolate::kRegExpUnicodeSetIncompatibilitiesWithUnicodeMode];
+  Local<v8::Context> context = isolate->GetCurrentContext();
+  {
+    v8_flags.harmony_regexp_unicode_sets = true;
+    std::ostringstream os;
+    os << "/[" << check_pattern << "]/v";
+    Local<v8::String> v8_source =
+        v8::String::NewFromUtf8(isolate, os.str().c_str()).ToLocalChecked();
+    MaybeLocal<v8::Script> script = v8::Script::Compile(context, v8_source);
+    CHECK(script.IsEmpty());
+    CHECK_EQ(
+        old_count,
+        use_counts
+            [v8::Isolate::kRegExpUnicodeSetIncompatibilitiesWithUnicodeMode]);
+  }
+  {
+    std::ostringstream os;
+    os << "/[" << check_pattern << "]/u";
+    Local<v8::String> v8_source =
+        v8::String::NewFromUtf8(isolate, os.str().c_str()).ToLocalChecked();
+    MaybeLocal<v8::Script> script = v8::Script::Compile(context, v8_source);
+    Local<v8::Value> result =
+        script.ToLocalChecked()->Run(context).ToLocalChecked();
+    CHECK(result->IsRegExp());
+    CHECK_EQ(
+        old_count + 1,
+        use_counts
+            [v8::Isolate::kRegExpUnicodeSetIncompatibilitiesWithUnicodeMode]);
+  }
+}
+
 }  // namespace
 
 using RegExpTestWithContext = TestWithContext;
@@ -1720,6 +1756,14 @@ TEST_F(RegExpTestWithContext, UseCountRegExp) {
   CHECK_EQ(2, use_counts[v8::Isolate::kRegExpPrototypeStickyGetter]);
   CHECK_EQ(1, use_counts[v8::Isolate::kRegExpPrototypeToString]);
   CHECK(resultToStringError->IsObject());
+
+  const char* incompatible_patterns[] = {
+      "(",  ")",  "[",  "{",  "}",  "/",  "-",   "|",  "&&",
+      "!!", "##", "$$", "%%", "**", "++", ",,",  "..", "::",
+      ";;", "<<", "==", ">>", "??", "@@", "^^^", "``", "~~"};
+  for (auto pattern : incompatible_patterns) {
+    CheckRegExpUnicodeSetIncompatibilitiesUseCounter(v8_isolate(), pattern);
+  }
 }
 
 class UncachedExternalString