src/share/vm/gc_implementation/parallelScavenge/objectStartArray.hpp

@@ -118,11 +118,13 @@
   void reset();
 
   MemRegion covered_region() { return _covered_region; }
 
   void allocate_block(HeapWord* p) {
-    assert(_covered_region.contains(p), "Must be in covered region");
+    assert(_covered_region.contains(p), 
+          err_msg("p (" PTR_FORMAT ") is not in covered region [" PTR_FORMAT ", " PTR_FORMAT ")",
+                 p2i(p), p2i(_covered_region.start()), p2i(_covered_region.end())));
     jbyte* block = block_for_addr(p);
     HeapWord* block_base = addr_for_block(block);
     size_t offset = pointer_delta(p, block_base, sizeof(HeapWord*));
     assert(offset < 128, "Sanity");
     // When doing MT offsets, we can't assert this.

@@ -133,11 +135,13 @@
   // Optimized for finding the first object that crosses into
   // a given block. The blocks contain the offset of the last
   // object in that block. Scroll backwards by one, and the first
   // object hit should be at the beginning of the block
   HeapWord* object_start(HeapWord* addr) const {
-    assert(_covered_region.contains(addr), "Must be in covered region");
+    assert(_covered_region.contains(addr), 
+          err_msg("addr (" PTR_FORMAT ") is not in covered region [" PTR_FORMAT ", " PTR_FORMAT ")",
+                 p2i(addr), p2i(_covered_region.start()), p2i(_covered_region.end())));
     jbyte* block = block_for_addr(addr);
     HeapWord* scroll_forward = offset_addr_for_block(block--);
     while (scroll_forward > addr) {
       scroll_forward = offset_addr_for_block(block--);
     }

@@ -151,11 +155,13 @@
     assert(addr <= next, "wrong order for arg and next");
     return scroll_forward;
   }
 
   bool is_block_allocated(HeapWord* addr) {
-    assert(_covered_region.contains(addr), "Must be in covered region");
+    assert(_covered_region.contains(addr), 
+          err_msg("addr (" PTR_FORMAT ") is not in covered region [" PTR_FORMAT ", " PTR_FORMAT ")",
+                 p2i(addr), p2i(_covered_region.start()), p2i(_covered_region.end())));
     jbyte* block = block_for_addr(addr);
     if (*block == clean_block)
       return false;
 
     return true;