search for: 283d630a

I need to read up on how nsw would make this different, but I see your point about the shift: %bf.result.shl = shl i8 %bf.value, 5 %bf.result.ashr = ashr i8 %bf.result.shl, 5 This should have splatted the sign bit across the upper 5 bits of the char, so the subsequent compare: %cmp = icmp slt i32 %bf.cast, 1 Can't be transformed to a check for 'equal to 0'. Thanks! On Fri,

I actually think it is a problem with the optimizer like Kay first thought. -instcombine seems turning "((x and 6) shl 5) slt 32" into "(x and 6) slt 1". If the comparison were unsigned or the shl had a nsw flag, I think this would be okay. Since none of these is true, I don't think this transformation is correct. H. On Sat, Nov 16, 2013 at 1:41 AM, Mark Lacey