On Mon, 2016-11-28 at 15:02 -0700, Jeff Law wrote: > On 11/28/2016 03:00 PM, David Malcolm wrote: > > On Mon, 2016-11-28 at 14:44 -0700, Jeff Law wrote: > > > 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. > > > > Could the RTL frontend be of use here? > Maybe -- but only on targets where we have the right insns in the > target > machine description.
Segher: it looks like the "PR78432" in the Subject line is a typo; that bug number appears to relate to go-dump.c and is marked as RESOLVED FIXED.
