> %metadata.as.i8ptr = getelementptr inbounds i8, i8* %var.as.i8ptr, > i64 %alloc.plus.metadata.size Sorry, typo here. The offset should obviously just try to get you past the original object rather than the whole allocation: %metadata.as.i8ptr = getelementptr inbounds i8, i8* %var.as.i8ptr, i64 %alloc.size Tim.