[regexp] Add use counters for slow exec and replace calls

These counters track how often the slow path of these two builtins is
hit. Exec is very permissive, its fast-path check doesn't look at the
regexp prototype at all. Replace is strict; any change on the
prototype will trigger the slow path.

Chromium CL: https://crrev.com/c/1875250

Bug: v8:5577
Change-Id: I9807f43829981445b75b5c5d29800cbdac9bc26a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1873698Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64496}

include/v8.h

@@ -8141,6 +8141,8 @@ class V8_EXPORT Isolate {
     kCallSiteAPIGetFunctionSloppyCall = 76,
     kCallSiteAPIGetThisSloppyCall = 77,
     kRegExpMatchAllWithNonGlobalRegExp = 78,
+    kRegExpExecCalledOnSlowRegExp = 79,
+    kRegExpReplaceCalledOnSlowRegExp = 80,
 
     // 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/builtins/builtins-regexp-gen.cc

@@ -701,6 +701,8 @@ RegExpBuiltinsAssembler::RegExpPrototypeExecBodyWithoutResult(
     TNode<Context> context, TNode<JSReceiver> maybe_regexp,
     TNode<String> string, const bool is_fastpath, Label* if_didnotmatch) {
   if (!is_fastpath) {
+    CallRuntime(Runtime::kIncrementUseCounter, context,
+                SmiConstant(v8::Isolate::kRegExpExecCalledOnSlowRegExp));
     ThrowIfNotInstanceType(context, maybe_regexp, JS_REG_EXP_TYPE,
                            "RegExp.prototype.exec");
   }

src/builtins/regexp-replace.tq

@@ -211,6 +211,9 @@ namespace regexp {
     }
   }
 
+  const kRegExpReplaceCalledOnSlowRegExp: constexpr int31
+  generates 'v8::Isolate::kRegExpReplaceCalledOnSlowRegExp';
+
   transitioning javascript builtin RegExpPrototypeReplace(
       js-implicit context: Context, receiver: JSAny)(...arguments): JSAny {
     const methodName: constexpr string = 'RegExp.prototype.@@replace';
@@ -250,6 +253,8 @@ namespace regexp {
       return RegExpReplace(fastRx, s, replaceValue);
     }
     label Runtime deferred {
+      IncrementUseCounter(
+          context, SmiConstant(kRegExpReplaceCalledOnSlowRegExp));
       return RegExpReplaceRT(context, rx, s, replaceValue);
     }
   }