Do more to avoid last-resort stop-the-world GC

test/cctest/test-alloc.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 20 matching lines @@
 #include "src/accessors.h"
 #include "src/api.h"
 
 
 using namespace v8::internal;
 
 
 static AllocationResult AllocateAfterFailures() {
   static int attempts = 0;
 
-  if (++attempts < 3) return AllocationResult::Retry();
+  // The first 4 times we simulate a full heap, by returning retry.
+  if (++attempts < 4) return AllocationResult::Retry();
+
+  // Expose some private stuff on Heap.
   TestHeap* heap = CcTest::test_heap();
 
+  // Now that we have returned 'retry' 4 times, we are in a last-chance
+  // scenario, with always_allocate.  See CALL_AND_RETRY.  Test that all
+  // allocations succeed.
+
   // New space.
   SimulateFullSpace(heap->new_space());
   heap->AllocateByteArray(100).ToObjectChecked();
   heap->AllocateFixedArray(100, NOT_TENURED).ToObjectChecked();
 
   // Make sure we can allocate through optimized allocation functions
   // for specific kinds.
   heap->AllocateFixedArray(100).ToObjectChecked();
   heap->AllocateHeapNumber(0.42).ToObjectChecked();
   Object* object = heap->AllocateJSObject(
@@ skipping 176 matching lines @@
       if (index < blocks.length() - 1) {
         blocks[index] = blocks.RemoveLast();
       } else {
         blocks.RemoveLast();
       }
     }
   }
 
   code_range.TearDown();
 }