From: Segher Boessenkool <segher@kernel.crashing.org>
To: Jiufu Guo <guojiufu@linux.ibm.com>
Cc: gcc-patches@gcc.gnu.org, dje.gcc@gmail.com, linkw@gcc.gnu.org
Subject: Re: [PATCH] rs6000: Enable generate const through pli+pli+rldimi
Date: Thu, 11 Aug 2022 08:48:28 -0500 [thread overview]
Message-ID: <20220811134828.GE25951@gate.crashing.org> (raw)
In-Reply-To: <7ev8qzkkm6.fsf@pike.rch.stglabs.ibm.com>
Hi!
On Thu, Aug 11, 2022 at 08:52:49PM +0800, Jiufu Guo wrote:
> Segher Boessenkool <segher@kernel.crashing.org> writes:
> > On Wed, Aug 10, 2022 at 03:11:23PM +0800, Jiufu Guo wrote:
> >> @@ -9659,7 +9659,7 @@ (define_split
> >> ;; When non-easy constants can go in the TOC, this should use
> >> ;; easy_fp_constant predicate.
> >> (define_split
> >> - [(set (match_operand:DI 0 "int_reg_operand_not_pseudo")
> >> + [(set (match_operand:DI 0 "gpc_reg_operand")
> >> (match_operand:DI 1 "const_int_operand"))]
> >> "TARGET_POWERPC64 && num_insns_constant (operands[1], DImode) > 1"
> >> [(set (match_dup 0) (match_dup 2))
> >
> > This is a huge change. Do you have some indication that it helps /
> > hurts / is neutral? Some reasoning why it is a good idea?
> Thanks for this concern! I would do more check/test for this.
>
> The 'int_reg_operand_not_pseudo' cause this splitter only work after RA.
> Using 'int_reg_operand_not_pseudo', the code sequence "pli+sldi+paddi"
> can be used.
Yes. Splitting early and to allowing pseudos is all good -- but this
was disallowed for a reason, supposedly.
Changing this now and then changing it back in a few weeks or months
isn't progress :-/
Segher
prev parent reply other threads:[~2022-08-11 13:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-10 7:11 Jiufu Guo
2022-08-10 16:43 ` Segher Boessenkool
2022-08-11 12:52 ` Jiufu Guo
2022-08-11 13:48 ` Segher Boessenkool [this message]
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