From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-199902-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 77981 invoked by alias); 12 Aug 2019 17:55:00 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 77973 invoked by uid 89); 12 Aug 2019 17:54:59 -0000
Authentication-Results: sourceware.org; auth=none
X-Spam-SWARE-Status: No, score=-1.5 required=5.0 tests=AWL,BAYES_05,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 spammy=fwa, optab, $a$b, add_truncba3
X-HELO: gate.crashing.org
Received: from gate.crashing.org (HELO gate.crashing.org) (63.228.1.57) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 12 Aug 2019 17:54:57 +0000
Received: from gate.crashing.org (localhost.localdomain [127.0.0.1])	by gate.crashing.org (8.14.1/8.14.1) with ESMTP id x7CHspcO001967;	Mon, 12 Aug 2019 12:54:52 -0500
Received: (from segher@localhost)	by gate.crashing.org (8.14.1/8.14.1/Submit) id x7CHsoTB001964;	Mon, 12 Aug 2019 12:54:50 -0500
Date: Mon, 12 Aug 2019 17:55:00 -0000
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Tejas Joshi <tejasjoshi9673@gmail.com>
Cc: gcc@gcc.gnu.org, Martin Jambor <mjambor@suse.cz>, hubicka@ucw.cz,        joseph@codesourcery.com
Subject: Re: Expansion of narrowing math built-ins into power instructions
Message-ID: <20190812175450.GB31406@gate.crashing.org>
References: <87sgqnx4i6.fsf@oldenburg2.str.redhat.com> <alpine.DEB.2.21.1907301947090.10734@digraph.polyomino.org.uk> <CACMrGjBiEMp7jj=b30MQ-8SMYoPA_4BFTdQRQSbV7WkYmv+Opg@mail.gmail.com> <20190731144722.GS31406@gate.crashing.org> <CACMrGjC5T-BNowawG9WiKi-C6FRMrtNKnkUSsn1TVT3iFN-Zdg@mail.gmail.com> <20190808200514.GL31406@gate.crashing.org> <alpine.DEB.2.21.1908082304570.5719@digraph.polyomino.org.uk> <CACMrGjB1UmfKuTCwGLi5oTapr4EM-JxbfVGr_GvwucWwfg0oYg@mail.gmail.com> <20190811165916.GX31406@gate.crashing.org> <CACMrGjAPa21OJ_ry+1HPyEQQbZhGOkQTVXwe=CvHsufc_ms_CQ@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CACMrGjAPa21OJ_ry+1HPyEQQbZhGOkQTVXwe=CvHsufc_ms_CQ@mail.gmail.com>
User-Agent: Mutt/1.4.2.3i
X-IsSubscribed: yes
X-SW-Source: 2019-08/txt/msg00096.txt.bz2

On Mon, Aug 12, 2019 at 11:01:11PM +0530, Tejas Joshi wrote:
> I have the following code in my rs6000.md (I haven't used new TARGET_* yet) :
> 
> (define_expand "add_truncdfsf3"
>   [(set (match_operand:SF 0 "gpc_reg_operand")
>        (float_truncate:SF
>        (plus:DF (match_operand:DF 1 "gpc_reg_operand")
>                 (match_operand:DF 2 "gpc_reg_operand"))))]
>   "TARGET_HARD_FLOAT"
>   "")
> 
> (define_insn "*add_truncdfsf3_fpr"
>   [(set (match_operand:SF 0 "gpc_reg_operand" "=f,wa")
>        (float_truncate:SF
>        (plus:DF (match_operand:DF 1 "gpc_reg_operand" "%d,wa")
>                 (match_operand:DF 2 "gpc_reg_operand" "d,wa"))))]
>   "TARGET_HARD_FLOAT"
>   "@
>    fadds %0,%1,%2
>    xsaddsp %x0,%x1,%x2"
>   [(set_attr "type" "fp")])

Those look fine.  You can also merge them into one:

(define_insn "add_truncdfsf3"
  [(set (match_operand:SF 0 "gpc_reg_operand" "=f,wa")
	(float_truncate:SF
	  (plus:DF (match_operand:DF 1 "gpc_reg_operand" "%d,wa")
		   (match_operand:DF 2 "gpc_reg_operand" "d,wa"))))]
  "TARGET_HARD_FLOAT"
  "@
   fadds %0,%1,%2
   xsaddsp %x0,%x1,%x2"
  [(set_attr "type" "fp")])

> with following optab in optabs.def :
> 
> OPTAB_CD(fadd_optab, "add_trunc$b$a3")             (what is the
> difference between $b$a and $a$b?)

Which of the two modes becomes $a and which becomes $b?  It depends on
the definition of fadd_optab what order is expected, I think.


Segher