Fix worst-case behavior of MergeRemovableSimulates().

test/mjsunit/regress/regress-2612.js

Index: test/mjsunit/regress/regress-2612.js
diff --git a/test/mjsunit/parallel-optimize-disabled.js b/test/mjsunit/regress/regress-2612.js
similarity index 63%
copy from test/mjsunit/parallel-optimize-disabled.js
copy to test/mjsunit/regress/regress-2612.js
index 86b375c53aef0c9118c7dbd57ad25f1dc593dda5..06db07733d393f5327be977c56d2b764fbe1f0b1 100644
--- a/test/mjsunit/parallel-optimize-disabled.js
+++ b/test/mjsunit/regress/regress-2612.js
@@ -25,22 +25,52 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --nodead-code-elimination --parallel-recompilation
-// Flags: --allow-natives-syntax
+// Flags: --allow-natives-syntax --nodead-code-elimination
+// Flags: --nofold-constants --nouse-gvn
 
-function g() {  // g() cannot be optimized.
-  const x = 1;
-  x++;
+// Create a function to get a long series of removable simulates.
+// f() {
+//   var _0 = <random>, _1 = <random>, ... _1000 = <random>,
+//   _1001 = <random var> + <random var>,
+//   _1002 = <random var> + <random var>,
+//   ...
+//   _99999 = <random var> + <random var>,
+//   x = 1;
+//   return _0;
+// }
+
+var seed = 1;
+
+function rand() {
+  seed = seed * 171 % 1337 + 17;
+  return (seed % 1000) / 1000;
 }
 
-function f(x) {
-  g();
+function randi(max) {
+  seed = seed * 131 % 1773 + 13;
+  return seed % max;
 }
 
-f();
+function varname(i) {
+  return "_" + i;
+}
+
+var source = "var ";
+
+for (var i = 0; i < 1000; i++) {
+  source += [varname(i), "=", rand(), ","].join("");
+}
+
+for (var i = 1000; i < 100000; i++) {
+  source += [varname(i), "=",
+             varname(randi(i)), "+",
+             varname(randi(i)), ","].join("");
+}
+
+source += "x=1; return _0;"
+var f = new Function(source);
+
 f();
 %OptimizeFunctionOnNextCall(f);
-%OptimizeFunctionOnNextCall(g, "parallel");
-f(0);  // g() is disabled for optimization on inlining attempt.
-// Attempt to optimize g() should not run into any assertion.
-%WaitUntilOptimized(g);
+f();
+