From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <richard.guenther@gmail.com>
Received: from mail-ej1-x62a.google.com (mail-ej1-x62a.google.com
 [IPv6:2a00:1450:4864:20::62a])
 by sourceware.org (Postfix) with ESMTPS id 191E63858C20;
 Wed,  9 Mar 2022 08:36:53 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 191E63858C20
Received: by mail-ej1-x62a.google.com with SMTP id kt27so3399396ejb.0;
 Wed, 09 Mar 2022 00:36:53 -0800 (PST)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20210112;
 h=x-gm-message-state:mime-version:references:in-reply-to:from:date
 :message-id:subject:to:cc;
 bh=J6atcKh7IsKRVuEVOQF43qbjT/2XkWNWYsuLYm5uBF4=;
 b=hqYZdmlDmRVxLKsLZ89wLjSAOO0ckpk98usIeU8Tw0BN6rNDOoJaKaoGDVsYoCKtVX
 ePM1ratu8GiqLNreV7HkSi070ekETXyI+ruZR7xm2JoTwwTkzNtJrvfRCYGrHLl2TyP/
 133hcKL5FZ6KACgoECLiPrL3E9wPD8qgTG7wgWofTAPBbOBqwFMbjhIg5hJjwLhh9jfT
 nbLQPbPWa7X+fXR2KiU5me7fAm50WXvHrp/xTnaBo2jBD/J7OvAMd5GXi91NCq1JWwZU
 s8ja8YUcYjzzoEg2khhwyhkcHiUWWxLJATt9H8LRcki5tg3aSJTzJPHbhq/dRF4YSkqV
 y8gg==
X-Gm-Message-State: AOAM531kCTT55wkGFVE/RWJFwnrbIOuIAghWl5garfCYjhdiUElGg3Pg
 sYrVQsQBjHOfxbosVQ399Ip+8xpryUEgX+gs4wl3y0d2
X-Google-Smtp-Source: ABdhPJyUJyr0DAyVsD+ZEcNBkL0lU4MRX7kH2aqJX6TmkZdOmNrbmUOHJ99TruaqqHy4ngyEM9zXjaeduMYdfHOp2xI=
X-Received: by 2002:a17:906:9b94:b0:6db:472:db87 with SMTP id
 dd20-20020a1709069b9400b006db0472db87mr15761806ejc.624.1646815011838; Wed, 09
 Mar 2022 00:36:51 -0800 (PST)
MIME-Version: 1.0
References: <CAJ_nqzgjpf_s97TUAMp84jpGJsZuxJiydC_hY2-55yWi1wZB6A@mail.gmail.com>
 <ri65yoopkeh.fsf@suse.cz>
 <CAJ_nqzhyib_Qu1JpPa0MgKvx_pTsyhwacAbbJSPZ8fqV99Rs4w@mail.gmail.com>
In-Reply-To: <CAJ_nqzhyib_Qu1JpPa0MgKvx_pTsyhwacAbbJSPZ8fqV99Rs4w@mail.gmail.com>
From: Richard Biener <richard.guenther@gmail.com>
Date: Wed, 9 Mar 2022 09:36:41 +0100
Message-ID: <CAFiYyc3FF6vGah7qx-enLk7UX920NY6Fx+9+5SUE494VRAx2Sg@mail.gmail.com>
Subject: Re: Question on updating function body on specialized functions
To: Erick Ochoa <eochoa@gcc.gnu.org>
Cc: Martin Jambor <mjambor@suse.cz>, GCC Development <gcc@gcc.gnu.org>
Content-Type: text/plain; charset="UTF-8"
X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,
 SPF_HELO_NONE, SPF_PASS, TXREP,
 T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on
 server2.sourceware.org
X-BeenThere: gcc@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc mailing list <gcc.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc>,
 <mailto:gcc-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <mailto:gcc-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc>,
 <mailto:gcc-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Wed, 09 Mar 2022 08:36:55 -0000

On Tue, Mar 8, 2022 at 4:31 PM Erick Ochoa via Gcc <gcc@gcc.gnu.org> wrote:
>
> Hi Martin!
>
> Thanks for replying, turns out that while I was trying to reply to you I
> was able to get the answer. Turns out there is indeed one tree node which
> is shared across the two functions. And that is
>
> TREE_OPERAND (MEM_REF, 1).
>
> When I was assigning to
>
> TREE_TYPE ( TREE_OPERAND (MEM_REF, 1) ) in one function, I was modifying
> the other. The solution was to create a new tree and assign it directly to
> TREE_OPERAND (MEM_REF, 1) in both functions.

Yes, that's because TREE_OPERAND (MEM_REF, 1) is an INTEGER_CST and
we share those.  See tree_node_can_be_shared in the sharing verifier.  Note
sharing also includes trees like &a.b.c[1].d for example.  The general rule of
thumb is to never directly modify trees but call unshare_expr () on them when
you do.

Richard.

>
> Thanks!