Define DEBUG for v8_optimized_debug=2

src/deoptimizer.h

Index: src/deoptimizer.h
diff --git a/src/deoptimizer.h b/src/deoptimizer.h
index 706d1f0523eb026b96fc0f0011aaf6bafcdea170..4e9d281ea52f762305a3435b364b88674dd2f55f 100644
--- a/src/deoptimizer.h
+++ b/src/deoptimizer.h
@@ -506,7 +506,15 @@ class FrameDescription {
   void SetCallerFp(unsigned offset, intptr_t value);
 
   intptr_t GetRegister(unsigned n) const {
-    ASSERT(n < ARRAY_SIZE(registers_));
+#if DEBUG
+    // This convoluted ASSERT is needed to work around a gcc problem that
+    // improperly detects an array bounds overflow in optimized debug builds
+    // when using a plain ASSERT.
+    if (n >= ARRAY_SIZE(registers_)) {
+      ASSERT(false);
+      return 0;
+    }
+#endif
     return registers_[n];
   }