[heap] New API for increasing the heap limit for debugging.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 6e5d788bd1d3644b0d0deb13a8f117ab63c91c42..26879c620404ceb6d71c226f879255b9e62795af 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -950,6 +950,23 @@ class Heap {
     return memory_pressure_level_.Value() != MemoryPressureLevel::kNone;
   }
 
+  void IncreaseHeapLimitForDebugging() {
+    const size_t kDebugHeapSizeFactor = 4;
+    size_t max_limit = std::numeric_limits<size_t>::max() / 4;
+    max_old_generation_size_ =
+        Max(max_old_generation_size_,
+            Min(max_limit,
+                initial_max_old_generation_size_ * kDebugHeapSizeFactor));
+  }
+
+  void RestoreOriginalHeapLimit() {
+    // Do not set the limit lower than the live size + some slack.
+    size_t min_limit = SizeOfObjects() + SizeOfObjects() / 4;
+    max_old_generation_size_ =
+        Min(max_old_generation_size_,
+            Max(initial_max_old_generation_size_, min_limit));
+  }
+
   // ===========================================================================
   // Initialization. ===========================================================
   // ===========================================================================
@@ -2131,6 +2148,7 @@ class Heap {
   size_t max_semi_space_size_;
   size_t initial_semispace_size_;
   size_t max_old_generation_size_;
+  size_t initial_max_old_generation_size_;
   size_t initial_old_generation_size_;
   bool old_generation_size_configured_;
   size_t max_executable_size_;