bytes_in_free_blocks  137 gc/checksums.c     word bytes_in_free_blocks = GC_large_free_bytes;
bytes_in_free_blocks  142 gc/checksums.c     		GC_bytes_in_used_blocks, bytes_in_free_blocks);
bytes_in_free_blocks  144 gc/checksums.c     if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {