From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 842 invoked by alias); 29 Dec 2014 03:07:10 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 825 invoked by uid 89); 29 Dec 2014 03:07:07 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.3.2 X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Mon, 29 Dec 2014 03:07:06 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 19685116203; Sun, 28 Dec 2014 22:07:05 -0500 (EST) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id SjxvLSNvlFzI; Sun, 28 Dec 2014 22:07:05 -0500 (EST) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id A37C0116204; Sun, 28 Dec 2014 22:07:04 -0500 (EST) Received: by joel.gnat.com (Postfix, from userid 1000) id E34794100E; Mon, 29 Dec 2014 07:06:59 +0400 (RET) Date: Mon, 29 Dec 2014 03:07:00 -0000 From: Joel Brobecker To: Yao Qi Cc: gdb-patches@sourceware.org Subject: Re: [PATCH] Clear upper bits during sign extension Message-ID: <20141229030659.GB2123@adacore.com> References: <1419815569-21854-1-git-send-email-yao@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1419815569-21854-1-git-send-email-yao@codesourcery.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SW-Source: 2014-12/txt/msg00651.txt.bz2 > 2014-12-29 Yao Qi > > * utils.c (gdb_sign_extend): Clear bits from BIT in VALUE. > --- > gdb/utils.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/gdb/utils.c b/gdb/utils.c > index 47adb67..e029863 100644 > --- a/gdb/utils.c > +++ b/gdb/utils.c > @@ -3031,6 +3031,15 @@ gdb_sign_extend (LONGEST value, int bit) > if (((value >> (bit - 1)) & 1) != 0) > { > LONGEST signbit = ((LONGEST) 1) << (bit - 1); > + LONGEST mask = 1; > + int i; > + > + /* Generate a mask in which bits [0, BIT - 1] are one. */ > + for (i = 0; i < bit; i++) > + mask = mask << 1; > + mask--; > + /* Clear bits from bit BIT. */ > + value &= mask; I think you can simplify the above with just: value &= ((LONGEST) 1 << bit) - 1; ? I don't know if the cast to LONGEST is really necessary, but we use it for signbit, so I did the same for the mask... -- Joel