[LLVMdev] x86 unwind support

Luke Dalessandro
Thu, 16 Jul 2009 16:52:24 -0000

Kenneth Uildriks wrote:
> 3. Perhaps a pass that lowers unwinds to an EH intrinsic?  Would that
> map well without adding more overhead than the current setjmp/longjmp
> lowering pass?

In the past there have been suggestions that a good approach would be to
target the libunwind (http://www.nongnu.org/libunwind/) library
interface in a lowering pass. This could provide both low
"availability"
overhead and low "use" overhead.

If libunwind had setjmp/longjmp implementations for your platform (I
think they're currently only available in IA64), then it would be
trivial to use a setjmp/longjmp lowering pass and get what you want.

I keep wanting to do this but it always seems to get bumped off of my
critical path.

Luke