Hi, On Thu, Dec 11, 2014 at 07:16:43PM +0100, Jan Hubicka wrote: > > On Thu, Dec 11, 2014 at 06:06:55PM +0100, Jan Hubicka wrote: > > > Hi, > > > in firefox .optimized dumps one can see few places where > > > __builtin_unreachable > > > is called (as a result of devirtualization code proving the code path to > > > be > > > undefined). There is usually some argument setup for the parameters of > > > __builtin_unreachable that are dead. This patch makes it somewhat better > > > so now we get: > > > <bb 30>: > > > > > > # prephitmp_222 = PHI <_52(27), pretmp_245(29)> > > > > > > _57 = prephitmp_222 + 2; > > > > > > pool_40(D)->ptr = _57; > > > > > > __builtin_unreachable (); > > > > > > > > > Why DSE does not eliminate the stores prior noreturn const function? > > > > > > Bootstrapped/regtested x86_64-linux, OK? > > > > > > Honza > > > * tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Remove dead > > > parameters > > > of BUILT_IN_UNREACHABLE > > > > Shouldn't this be done when you actually change the call to > > __builtin_unreachable ()? I mean, __builtin_unreachable () has no > > arguments, so leaving any arguments there is broken IL, even if you clean it > > up during the next DCE. > > Hmm, I tought there was some reason to not do so becuase of inplace folding > and memory-SSA. > I can give a try to update all the places we can put builtin_unreachable into > IL. > (I wonder if that also include standard constant propagation)
I think that's what we ought to do, see also PR 61591. Martin
