> Please note that there is no guarantee that "(set (reg1:QI) > (expression:QI))" will preserve high-order bits. This is guaranteed > only when strict_low_part is used on the destination operand. > > C.f. *addqi_1 pattern, where QImode plus RTX can emit SImode ADDL insn > vs. *addqi_1_slp, where QImode ADDQ insn is always emitted. > > So, the assumption in your last sentece is invalid, as far as x86 is > concerned.
OK, thanks, if that's the consensus, I'll stick to version #1. -- Eric Botcazou
