From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6357 invoked by alias); 9 Sep 2014 10:06:39 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 6346 invoked by uid 89); 9 Sep 2014 10:06:38 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pa0-f42.google.com Received: from mail-pa0-f42.google.com (HELO mail-pa0-f42.google.com) (209.85.220.42) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Tue, 09 Sep 2014 10:06:36 +0000 Received: by mail-pa0-f42.google.com with SMTP id lj1so3887394pab.1 for ; Tue, 09 Sep 2014 03:06:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type; bh=8QxuFNsqrooI6QjubW23wezV503L5q3NFsgjcsM1piE=; b=NVQd27G7Ic/OJ4BFAcHZBqdWnClYCoiySM1mvzu+KqRgtdSJfSXxv41Jx1darAn/Yv ElOItLK9gPSA7Na5iPQQqfAaM49WacMNwabVlFGKfUjPsl2OL9HwliguKDNltU1xLZmP Hk9msjSbAtq8uK2bc45fJTldyotAdd5NhTSKEjjt/4BGKGMnsBRf0oN3hBsYxSKWBofH r5K2X59RBSQQCu/ZDTD3qDfQfmw1Ol2qdwL8YjucnrKc7QxyM96+//GqcVUCIk/Ejkal kpBponuXtVJyywdIXYWOgYTPTJeFLb60xlDTMsBT27kZdiNhsadQTdlzVrAvyR27sEb2 7Nvg== X-Gm-Message-State: ALoCoQnrRdNzBw/QxJIiNN2HuFMjbuQLzuxc2rpJG9wee3cKpOqAvCvwaXc/A21QHD1ib1efySEp X-Received: by 10.66.123.75 with SMTP id ly11mr55252854pab.82.1410257194668; Tue, 09 Sep 2014 03:06:34 -0700 (PDT) Received: from [10.1.1.2] (58-6-183-210.dyn.iinet.net.au. [58.6.183.210]) by mx.google.com with ESMTPSA id fk10sm11890447pab.29.2014.09.09.03.06.31 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Sep 2014 03:06:33 -0700 (PDT) Message-ID: <540ED116.9030907@linaro.org> Date: Tue, 09 Sep 2014 10:06:00 -0000 From: Kugan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Richard Biener CC: Uros Bizjak , "gcc-patches@gcc.gnu.org" , Jakub Jelinek Subject: Re: [PATCH 2/2] Enable elimination of zext/sext References: <53FEDF34.4090605@linaro.org> <5407DF57.2040902@linaro.org> <540912E1.30505@linaro.org> <540C2A7E.7050105@linaro.org> In-Reply-To: Content-Type: multipart/mixed; boundary="------------010903080607020400010407" X-IsSubscribed: yes X-SW-Source: 2014-09/txt/msg00672.txt.bz2 This is a multi-part message in MIME format. --------------010903080607020400010407 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-length: 3667 On 08/09/14 19:48, Richard Biener wrote: > On Sun, Sep 7, 2014 at 11:50 AM, Kugan > wrote: >> On 05/09/14 19:50, Richard Biener wrote: >> >>> Well - the best way would be to expose the target specifics to GIMPLE >>> at some point in the optimization pipeline. My guess would be that it's >>> appropriate after loop optimizations (but maybe before induction variable >>> optimization). >>> >>> That is, have a pass that applies register promotion to all SSA names >>> in the function, inserting appropriate truncations and extensions. That >>> way you'd never see (set (subreg...) on RTL. The VRP and DOM >>> passes running after that pass would then be able to aggressively >>> optimize redundant truncations and extensions. >>> >>> Effects on debug information are to be considered. You can change >>> the type of SSA names in-place but you don't want to do that for >>> user DECLs (and we can't have the SSA name type and its DECL >>> type differ - and not sure if we might want to lift that restriction). >> >> Thanks. I will try to implement this. >> >> I still would like to keep the VRP based approach as there are some >> cases that I think can only be done with range info. For example: >> >> short foo(unsigned char c) >> { >> c = c & (unsigned char)0x0F; >> if( c > 7 ) >> return((short)(c - 5)); >> else >> return(( short )c); >> } >> >> >> So, how about adding and setting the overflow/wrap around flag to >> range_info. We now set static_flag for VR_RANG/VR_ANTI_RANGE. If we go >> back to the max + 1, min - 1 for VR_ANTI_RANGE, we can use this >> static_flag to encode overflow/wrap around. Will that be something >> acceptable? > > You mean tracking in the VRP lattice whether a value wrapped around > (or was assumed not to due to undefined behavior)? I'm not sure this > is easy to do correctly (VRP is large). > > Note that I don't think we'll lose the testcase you quoted if the promotion > pass runs before VRP2. We'd have as input to VRP2 sth like (assuming > promote mode would promote to SImode) > > SImode tem_2 = (unsigned int)c_1(D); > tem_3 = tem_3 & 0xF; > if (tem_3 > 7) > { > tem_4 = tem_3 - 5; > short _5 = (short)_4; > tem_5 = (unsigned int)_5; > return tem_5; > } > else > { > short _6 = (short)_3; > return _6; > } > > VRP should be able to remove the (unsigned int)(short) sign-extension > of tem_4. > > note that both incoming registers and return registers are "interesting". > For simplicity I suggest to not promote them on GIMPLE. > > What you'd lose in VRP2 is the smaller value-ranges you'd get from > (undefined) wrapping. You could recover the undefinedness by > looking at SSA names recorded value-range and transfering that > in the promotion pass (but I'm not sure if you want to open the > can of latent signed overflow bugs in programs even more for > PROMOTE_MODE targets...) > Thanks. In the meantime I would like to revert the patch which is enabling zero/sign extension. I have bootstrapped it in x86_64 and regression testing is ongoing. Is this OK ? Thanks, Kugan gcc/ChangeLog: 2014-09-09 Kugan Vivekanandarajah Revert r213751: * calls.c (precompute_arguments): Check promoted_for_signed_and_unsigned_p and set the promoted mode. (promoted_for_signed_and_unsigned_p): New function. (expand_expr_real_1): Check promoted_for_signed_and_unsigned_p and set the promoted mode. * expr.h (promoted_for_signed_and_unsigned_p): New function definition. * cfgexpand.c (expand_gimple_stmt_1): Call emit_move_insn if SUBREG is promoted with SRP_SIGNED_AND_UNSIGNED. --------------010903080607020400010407 Content-Type: text/plain; charset=UTF-8; name="p.txt" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="p.txt" Content-length: 5271 ZGlmZiAtLWdpdCBhL2djYy9jYWxscy5jIGIvZ2NjL2NhbGxzLmMKaW5kZXgg MDNlZDljOC4uMzQ1MzMxZiAxMDA2NDQKLS0tIGEvZ2NjL2NhbGxzLmMKKysr IGIvZ2NjL2NhbGxzLmMKQEAgLTE0ODYsMTAgKzE0ODYsNyBAQCBwcmVjb21w dXRlX2FyZ3VtZW50cyAoaW50IG51bV9hY3R1YWxzLCBzdHJ1Y3QgYXJnX2Rh dGEgKmFyZ3MpCiAJICAgICAgYXJnc1tpXS5pbml0aWFsX3ZhbHVlCiAJCT0g Z2VuX2xvd3BhcnRfU1VCUkVHIChtb2RlLCBhcmdzW2ldLnZhbHVlKTsKIAkg ICAgICBTVUJSRUdfUFJPTU9URURfVkFSX1AgKGFyZ3NbaV0uaW5pdGlhbF92 YWx1ZSkgPSAxOwotCSAgICAgIGlmIChwcm9tb3RlZF9mb3Jfc2lnbmVkX2Fu 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