Revert "[regexp] Eagerly tier-up for very long strings"

This reverts commit cfb60d43.

Reason for revert: Several bots timing out, e.g.
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20gc%20stress/24717

Original change's description:
> [regexp] Eagerly tier-up for very long strings
>
> For very long subject strings, the regexp interpreter is currently much slower
> than the native machine code execution. This CL implements eager tier-up to the
> compiler to avoid the performance penalty for subject strings of length greater
> than 1000.
>
> Change-Id: I244ccbd60255e0f3bedc493b1cc3d25cdd42133e
> Bug: v8:9566
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1829273
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Commit-Queue: Ana Pesko <anapesko@google.com>
> Cr-Commit-Position: refs/heads/master@{#64046}

TBR=yangguo@chromium.org,petermarshall@chromium.org,anapesko@google.com

TBR=yangguo@chromium.org

Change-Id: Id8dd362617988c8c5efa87ae157ee91c96cb1fdf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9566
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1832163Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Ana Pesko <anapesko@google.com>
Cr-Commit-Position: refs/heads/master@{#64047}

src/objects/js-regexp.h

@@ -200,10 +200,6 @@ class JSRegExp : public TorqueGeneratedJSRegExp<JSRegExp, JSObject> {
   // The uninitialized value for a regexp code object.
   static const int kUninitializedValue = -1;
 
-  // The heuristic value for the length of the subject string for which we
-  // tier-up to the compiler immediately, instead of using the interpreter.
-  static constexpr int kTierUpForSubjectLengthValue = 1000;
-
   TQ_OBJECT_CONSTRUCTORS(JSRegExp)
 };
 

src/regexp/regexp.cc

@@ -600,20 +600,6 @@ MaybeHandle<Object> RegExpImpl::IrregexpExec(
   }
 #endif
 
-  // For very long subject strings, the regexp interpreter is currently much
-  // slower than the jitted code execution. If the tier-up strategy is turned
-  // on, we want to avoid this performance penalty so we eagerly tier-up if the
-  // subject string length is equal or greater than the given heuristic value.
-  if (FLAG_regexp_tier_up &&
-      subject->length() >= JSRegExp::kTierUpForSubjectLengthValue) {
-    regexp->MarkTierUpForNextExec();
-    if (FLAG_trace_regexp_tier_up) {
-      PrintF(
-          "Forcing tier-up for very long strings in "
-          "RegExpImpl::IrregexpExec\n");
-    }
-  }
-
   // Prepare space for the return values.
   int required_registers = RegExp::IrregexpPrepare(isolate, regexp, subject);
   if (required_registers < 0) {

test/mjsunit/regexp-tier-up.js

@@ -91,15 +91,3 @@ assertTrue(!%RegexpHasBytecode(re_g, kLatin1) &&
             %RegexpHasNativeCode(re_g, kLatin1));
 assertTrue(!%RegexpHasBytecode(re_g, kUnicode) &&
             !%RegexpHasNativeCode(re_g, kUnicode));
-
-// Testing eager tier-up for very long strings.
-let dna = "ATCG".repeat(251);
-
-re_g = />.*\n|\n/;
-CheckRegexpNotYetCompiled(re_g);
-
-dna = dna.replace(re_g,"");
-assertTrue(!%RegexpHasBytecode(re_g, kLatin1) &&
-            %RegexpHasNativeCode(re_g, kLatin1));
-assertTrue(!%RegexpHasBytecode(re_g, kUnicode) &&
-            !%RegexpHasNativeCode(re_g, kUnicode));