Date: Thu, 01 Dec 2022 09:48:06 +0800
In-Reply-To: <20221128171950.gn25...@gate.crashing.org> (Segher Boessenkool's
message of "Mon, 28 Nov 2022 11:19:50 -0600")
Message-ID: <7e4jufyjvt....@pike.rch.stglabs.ibm.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux)
Segher Boessenkool <seg...@kernel.crashing.org> writes:
> 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))
I just submit a simple patch for this:
https://gcc.gnu.org/pipermail/gcc-patches/2022-December/607589.html
Thanks for comments!
BR,
Jeff (Jiufu)
>
>
> Segher
