On Sat, 2005-05-07 at 04:14, Richard Henderson wrote: > On Fri, May 06, 2005 at 01:59:06PM -0700, Steve Ellcey wrote: > > I was wondering if anyone could tell me how to write an (empty) > > instruction pattern that does a truncate/extend conversion on a register > > 'in place'. > > > > All the conversions I see are like this one in ia64/ia64.md: > > > > (define_insn "extendsfdf2" > > [(set (match_operand:DF 0 "fr_register_operand" "=f") > > (float_extend:DF (match_operand:SF 1 "fr_register_operand" "f")))] > > "" > > "fnorm.d %0 = %1" > > [(set_attr "itanium_class" "fmac")]) > > > > Where the source and the destination may or may not be the same > > register. > > The best way is to have a post-reload splitter that splits the insn > into nothing at all.
Is that really valid? I would have thought it would break the data flow. R.
