On 11/23/2016 04:55 PM, Segher Boessenkool wrote:
Combine can turn a conditional trap into an unconditional trap. If it
does that it should make the code after it unreachable (an unconditional
trap should be the last insn in its bb, and that bb has no successors).
This patch seems to work. It is hard to be sure, this is very hard to
trigger. Quite a few other passes look like they need something similar
as well, but I don't see anything else handling it yet either.
How does this look? Any better ideas?
It's probably a reasonable place to start as there's lots of
similarities to converting a conditional branch to an unconditional.
Like you I worry there may be other instances of this issue may be lurking.
The possibility of having a conditional trap in the IL turn into an
unconditional trap has always been there. As you note, it's somewhat
difficult to trigger since the SSA optimizers ought to expose/optimize
this long before we get to RTL.
Jeff
