Limit code size generated for very large regexps

test/cctest/test-heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
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@@ skipping 1584 matching lines @@
   CHECK_EQ(opt ? 4 : 0, CountOptimizedUserFunctions(ctx[0]));
   CHECK_EQ(opt ? 4 : 0, CountOptimizedUserFunctionsWithGC(ctx[0], 2));
   CompileRun("f5()");
   CHECK_EQ(opt ? 5 : 0, CountOptimizedUserFunctions(ctx[0]));
   CHECK_EQ(opt ? 5 : 0, CountOptimizedUserFunctionsWithGC(ctx[0], 4));
 
   ctx[0]->Exit();
 }
 
 
+TEST(TestSizeOfRegExpCode) {
+  if (!FLAG_regexp_optimization) return;
+
+  v8::V8::Initialize();
+
+  Isolate* isolate = CcTest::i_isolate();
+  HandleScope scope(isolate);
+
+  LocalContext context;
+
+  // 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 < 10000) {"

[Jakob Kummerow, 2014/12/15 20:00:29]

The limit here mirrors kRegExpTooLargeToOptimize, right? Maybe add a
STATIC_ASSERT here with a comment that the test needs to be updated if the limit
is changed.

[Erik Corry, 2014/12/16 12:05:33]

Done.

+      "  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();
 
   // 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);
@@ skipping 2890 matching lines @@
 #ifdef DEBUG
 TEST(PathTracer) {
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
 
   v8::Local<v8::Value> result = CompileRun("'abc'");
   Handle<Object> o = v8::Utils::OpenHandle(*result);
   CcTest::i_isolate()->heap()->TracePathToObject(*o);
 }
 #endif  // DEBUG