Add a nothrow flag to the SIL apply_inst.

If the compiler can prove that a throwing function actually does not throw it can
replace a try_apply with an "apply [nothrow]". Such an apply_inst calls a function
with an error result but does not have the overhead of checking for the error case.

Currently this flag is not set, yet.



Swift SVN r31151

lib/SILGen/SILGenFunction.cpp

@@ -777,7 +777,7 @@ ApplyInst *SILGenBuilder::createApply(SILLocation Loc, SILValue Fn,
                                       ArrayRef<Substitution> Subs,
                                       ArrayRef<SILValue> Args) {
   SGM.useConformancesFromSubstitutions(Subs);
-  return SILBuilder::createApply(Loc, Fn, SubstFnTy, Result, Subs, Args);
+  return SILBuilder::createApply(Loc, Fn, SubstFnTy, Result, Subs, Args, false);
 }
 
 TryApplyInst *SILGenBuilder::createTryApply(SILLocation loc, SILValue Fn,