Cherry-pick "Refactor Regexp.prototype"
Original change: https://chromium-review.googlesource.com/c/v8/v8/+/1547660

Bug: 147664838
Test: pacrunner32 test.pac
Test: gts-tradefed run gts-dev --module GtsGmscoreHostTestCases --test com.google.android.gts.devicepolicy.DeviceOwnerTest#testProxyPacProxyTest

Change-Id: Iac9370d48ca0ed84d5903ab0469c0ae01d62a621
Merged-In: Iac9370d48ca0ed84d5903ab0469c0ae01d62a621
(cherry picked from commit df2d4b58f6fa0d0f0c563eac34d0bea2768d9bec)
diff --git a/src/regexp/regexp-utils.cc b/src/regexp/regexp-utils.cc
index c787a50..8d4b160 100644
--- a/src/regexp/regexp-utils.cc
+++ b/src/regexp/regexp-utils.cc
@@ -36,7 +36,7 @@
 
 namespace {
 
-V8_INLINE bool HasInitialRegExpMap(Isolate* isolate, Handle<JSReceiver> recv) {
+V8_INLINE bool HasInitialRegExpMap(Isolate* isolate, JSReceiver* recv) {
   return recv->map() == isolate->regexp_function()->initial_map();
 }
 
@@ -47,7 +47,7 @@
                                               uint64_t value) {
   Handle<Object> value_as_object =
       isolate->factory()->NewNumberFromInt64(value);
-  if (HasInitialRegExpMap(isolate, recv)) {
+  if (HasInitialRegExpMap(isolate, *recv)) {
     JSRegExp::cast(*recv)->set_last_index(*value_as_object, SKIP_WRITE_BARRIER);
     return recv;
   } else {
@@ -59,7 +59,7 @@
 
 MaybeHandle<Object> RegExpUtils::GetLastIndex(Isolate* isolate,
                                               Handle<JSReceiver> recv) {
-  if (HasInitialRegExpMap(isolate, recv)) {
+  if (HasInitialRegExpMap(isolate, *recv)) {
     return handle(JSRegExp::cast(*recv)->last_index(), isolate);
   } else {
     return Object::GetProperty(isolate, recv,
@@ -147,9 +147,7 @@
 
   JSReceiver* recv = JSReceiver::cast(*obj);
 
-  // Check the receiver's map.
-  Handle<JSFunction> regexp_function = isolate->regexp_function();
-  if (recv->map() != regexp_function->initial_map()) return false;
+  if (!HasInitialRegExpMap(isolate, recv)) return false;
 
   // Check the receiver's prototype's map.
   Object* proto = recv->map()->prototype();
diff --git a/src/runtime/runtime-regexp.cc b/src/runtime/runtime-regexp.cc
index 3e77bf1..6c2f6d2 100644
--- a/src/runtime/runtime-regexp.cc
+++ b/src/runtime/runtime-regexp.cc
@@ -1295,10 +1295,9 @@
 // doesn't properly call the underlying exec method.
 V8_WARN_UNUSED_RESULT MaybeHandle<String> RegExpReplace(
     Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> string,
-    Handle<Object> replace_obj) {
+    Handle<String> replace) {
   // Functional fast-paths are dispatched directly by replace builtin.
   DCHECK(RegExpUtils::IsUnmodifiedRegExp(isolate, regexp));
-  DCHECK(!replace_obj->IsCallable());
 
   Factory* factory = isolate->factory();
 
@@ -1306,9 +1305,6 @@
   const bool global = (flags & JSRegExp::kGlobal) != 0;
   const bool sticky = (flags & JSRegExp::kSticky) != 0;
 
-  Handle<String> replace;
-  ASSIGN_RETURN_ON_EXCEPTION(isolate, replace,
-                             Object::ToString(isolate, replace_obj), String);
   replace = String::Flatten(isolate, replace);
 
   Handle<RegExpMatchInfo> last_match_info = isolate->regexp_last_match_info();
@@ -1408,18 +1404,23 @@
   CONVERT_ARG_HANDLE_CHECKED(String, subject, 1);
   CONVERT_ARG_HANDLE_CHECKED(RegExpMatchInfo, last_match_info, 2);
   CONVERT_ARG_HANDLE_CHECKED(JSArray, result_array, 3);
+
+  DCHECK(RegExpUtils::IsUnmodifiedRegExp(isolate, regexp));
   CHECK(result_array->HasObjectElements());
 
   subject = String::Flatten(isolate, subject);
   CHECK(regexp->GetFlags() & JSRegExp::kGlobal);
 
+  Object* result;
   if (regexp->CaptureCount() == 0) {
-    return SearchRegExpMultiple<false>(isolate, subject, regexp,
-                                       last_match_info, result_array);
+    result = SearchRegExpMultiple<false>(isolate, subject, regexp,
+                                         last_match_info, result_array);
   } else {
-    return SearchRegExpMultiple<true>(isolate, subject, regexp, last_match_info,
-                                      result_array);
+    result = SearchRegExpMultiple<true>(isolate, subject, regexp,
+                                        last_match_info, result_array);
   }
+  DCHECK(RegExpUtils::IsUnmodifiedRegExp(isolate, regexp));
+  return result;
 }
 
 RUNTIME_FUNCTION(Runtime_StringReplaceNonGlobalRegExpWithFunction) {
@@ -1736,14 +1737,6 @@
 
   string = String::Flatten(isolate, string);
 
-  // Fast-path for unmodified JSRegExps.
-  if (RegExpUtils::IsUnmodifiedRegExp(isolate, recv)) {
-    RETURN_RESULT_OR_FAILURE(
-        isolate, RegExpReplace(isolate, Handle<JSRegExp>::cast(recv), string,
-                               replace_obj));
-  }
-
-  const uint32_t length = string->length();
   const bool functional_replace = replace_obj->IsCallable();
 
   Handle<String> replace;
@@ -1752,6 +1745,21 @@
                                        Object::ToString(isolate, replace_obj));
   }
 
+  // Fast-path for unmodified JSRegExps (and non-functional replace).
+  if (RegExpUtils::IsUnmodifiedRegExp(isolate, recv)) {
+    // We should never get here with functional replace because unmodified
+    // regexp and functional replace should be fully handled in CSA code.
+    CHECK(!functional_replace);
+    Handle<Object> result;
+    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+        isolate, result,
+        RegExpReplace(isolate, Handle<JSRegExp>::cast(recv), string, replace));
+    DCHECK(RegExpUtils::IsUnmodifiedRegExp(isolate, recv));
+    return *result;
+  }
+
+  const uint32_t length = string->length();
+
   Handle<Object> global_obj;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, global_obj,