Make string test resilient against GC stress.

test/cctest/test-strings.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 
 // Check that we can traverse very deep stacks of ConsStrings using
 // StringInputBuffer.  Check that Get(int) works on very deep stacks
 // of ConsStrings.  These operations may not be very fast, but they
 // should be possible without getting errors due to too deep recursion.
 
 #include <stdlib.h>
 
 #include "v8.h"
@@ skipping 653 matching lines @@
 }
 
 
 template<typename BuildString>
 void TestStringCharacterStream(BuildString build, int test_cases) {
   InitializeVM();
   Isolate* isolate = Isolate::Current();
   HandleScope outer_scope(isolate);
   ZoneScope zone(Isolate::Current()->runtime_zone(), DELETE_ON_EXIT);
   ConsStringGenerationData data(true);
-  bool last_test_did_gc = false;
   for (int i = 0; i < test_cases; i++) {
     printf("%d\n", i);
     HandleScope inner_scope(isolate);
+    AlwaysAllocateScope always_allocate;
     // Build flat version of cons string.
     Handle<String> flat_string = build(i, &data);
     ConsStringStats flat_string_stats;
     AccumulateStats(flat_string, &flat_string_stats);
     // Flatten string.
     FlattenString(flat_string);
     // Build unflattened version of cons string to test.
     Handle<String> cons_string = build(i, &data);
     ConsStringStats cons_string_stats;
     AccumulateStats(cons_string, &cons_string_stats);
-    // Check if gc changed our data structure.
-    bool broken_by_gc =
-        cons_string_stats.leaves_ != data.stats_.leaves_ ||
-        cons_string_stats.leaves_ != flat_string_stats.leaves_;
-    // If gc altered the data structure, do a full collection and retry test.
-    if (broken_by_gc) {
-      // Bail if test runs twice.
-      if (last_test_did_gc) CHECK(false);
-      printf("forcing gc\n");
-      isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags, "retry test");
-      // Retry test.
-      last_test_did_gc = true;
-      i--;
-      continue;
-    }
-    last_test_did_gc = false;
     AssertNoAllocation no_alloc;
     PrintStats(data);
     // Full verify of cons string.
     cons_string_stats.VerifyEqual(flat_string_stats);
     cons_string_stats.VerifyEqual(data.stats_);
     VerifyConsString(cons_string, &data);
     String* flat_string_ptr =
         flat_string->IsConsString() ?
         ConsString::cast(*flat_string)->first() :
         *flat_string;
@@ skipping 596 matching lines @@
 
   v8::Local<v8::String> expected = v8_str("ascii\x80only\x80string\x80");
   CHECK(expected->Equals(result));
 }
 
 
 TEST(IsAscii) {
   CHECK(String::IsAscii(static_cast<char*>(NULL), 0));
   CHECK(String::IsAscii(static_cast<uc16*>(NULL), 0));
 }