Limit code size generated for very large regexps

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index ee476db6cdc4729b1a65a560fe03734a65f2bfdb..5da64174e3e5c5809f68ca43a24afac50711c1ff 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -1602,6 +1602,64 @@ TEST(TestInternalWeakListsTraverseWithGC) {
 }
 
 
+TEST(TestSizeOfRegExpCode) {
+  if (!FLAG_regexp_optimization) return;
+
+  v8::V8::Initialize();
+
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+
+  LocalContext context;
+
+  // Adjust source below and this check to match
+  // RegExpImple::kRegExpTooLargeToOptimize.
+  DCHECK_EQ(i::RegExpImpl::kRegExpTooLargeToOptimize, 10 * KB);
+
+  // Compile a regexp that is much larger if we are using regexp optimizations.
+  CompileRun(
+      "var reg_exp_source = '(?:a|bc|def|ghij|klmno|pqrstu)';"
+      "var half_size_reg_exp;"
+      "while (reg_exp_source.length < 10 * 1024) {"
+      "  half_size_reg_exp = reg_exp_source;"
+      "  reg_exp_source = reg_exp_source + reg_exp_source;"
+      "}"
+      // Flatten string.
+      "reg_exp_source.match(/f/);");
+
+  // Get initial heap size after several full GCs, which will stabilize
+  // the heap size and return with sweeping finished completely.
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  MarkCompactCollector* collector = CcTest::heap()->mark_compact_collector();
+  if (collector->sweeping_in_progress()) {
+    collector->EnsureSweepingCompleted();
+  }
+  int initial_size = static_cast<int>(CcTest::heap()->SizeOfObjects());
+
+  CompileRun("'foo'.match(reg_exp_source);");
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  int size_with_regexp = static_cast<int>(CcTest::heap()->SizeOfObjects());
+
+  CompileRun("'foo'.match(half_size_reg_exp);");
+  CcTest::heap()->CollectAllGarbage(Heap::kNoGCFlags);
+  int size_with_optimized_regexp =
+      static_cast<int>(CcTest::heap()->SizeOfObjects());
+
+  int size_of_regexp_code = size_with_regexp - initial_size;
+
+  CHECK_LE(size_of_regexp_code, 500 * KB);
+
+  // Small regexp is half the size, but compiles to more than twice the code
+  // due to the optimization steps.
+  CHECK_GE(size_with_optimized_regexp,
+           size_with_regexp + size_of_regexp_code * 2);
+}
+
+
 TEST(TestSizeOfObjects) {
   v8::V8::Initialize();