undefined | Better HN

0 pointshinkley1y ago0 comments

memcpy gets weird with pointer aliasing as well. There's a slower path if the pointers can end up overlapping, and you either have to prove it programatically like Java does, do the defensive copy, or YOLO it and hope.

0 comments

nyanpasu641y ago

memcpy is only defined for non-overlapping memory regions (otherwise you should use memmove), but many platforms use memmove for memcpy anyway to avoid breaking user programs in unpredictable ways. Apparently this has also led to some arguments and glibc version incompatibilities (https://www.win.tue.nl/~aeb/linux/misc/gcc-semibug.html).

hinkleyOP1y ago

I don’t know why I said “path”, I meant instruction.

j / k navigate · click thread line to collapse

0 comments

nyanpasu641y ago

hinkleyOP1y ago

I don’t know why I said “path”, I meant instruction.

j / k navigate · click thread line to collapse