On Mon, Nov 28, 2022 at 03:51:59PM +0800, Jiufu Guo wrote:
> Jiufu Guo via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> > Segher Boessenkool <seg...@kernel.crashing.org> writes:
> >>> > + else
> >>> > + {
> >>> > + emit_move_insn (temp,
> >>> > + GEN_INT (((ud2 << 16) ^ 0x80000000) -
> >>> > 0x80000000));
> >>> > + if (ud1 != 0)
> >>> > + emit_move_insn (temp, gen_rtx_IOR (DImode, temp, GEN_INT
> >>> > (ud1)));
> >>> > + emit_move_insn (dest,
> >>> > + gen_rtx_ZERO_EXTEND (DImode,
> >>> > + gen_lowpart (SImode,
> >>> > temp)));
> >>> > + }
> >>
> >> Why this? Please just write it in DImode, do not go via SImode?
> > Thanks for catch this. Yes, gen_lowpart with DImode would be ok.
> Oh, Sorry. DImode can not be used here. The genreated pattern with
> DImode can not be recognized. Using SImode is to match 'rlwxx'.
There are patterns that accept DImode for rlwinm just fine. Please use
(and:DI (const_int 0xffffffff) (x:DI))
not the obfuscated
(zero_extend:DI (subreg:SI (x:DI) LOWBYTE))
Segher
