search for: undefinst

...undef. Accept that this is ok because optimizing undefined behavior is not actually interesting. As I said above, we don't really care about folding cases that we've proved to have UB. Moreover, in your scheme, we still won't be able to do optimizations like: %y = ... %undef.0 = undefinst %val = select i1 %cond, %undef.0, %y print(%val) to %y = ... print(%val) since it could have been that %x = INT_MAX at runtime, but unknown at compile time %y = %x +nsw 1 %undef.0 = undefinst %val = select i1 %cond, %undef.0, %y print(%val) == %x s< %val Folding %val to...

...is not actually interesting. >> As I said above, we don't really care about folding cases that we've >> proved to have UB. >> >> Moreover, in your scheme, we still won't be able to do optimizations >> like: >> >> %y = ... >> %undef.0 = undefinst >> %val = select i1 %cond, %undef.0, %y >> print(%val) >> >> to >> >> %y = ... >> print(%val) >> >> since it could have been that >> >> %x = INT_MAX at runtime, but unknown at compile time >> %y = %x +nsw 1 >&g...

> On 11/8/2016 3:32 PM, Sanjoy Das wrote: >> Hi Nuno, Chandler, >> >> Nuno Lopes via llvm-dev wrote: >> > This program stores 8 bits, and leaves the remaining 24 bits >> > uninitialized. It then loads 16 bits, half initialized to %v, half >> > uninitialized. SROA transforms the above function to: >> > >> > define i16 @g(i8 %in) {