From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-385458-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 12855 invoked by alias); 6 Mar 2012 11:26:13 -0000
Received: (qmail 12822 invoked by uid 22791); 6 Mar 2012 11:26:12 -0000
X-SWARE-Spam-Status: No, hits=-2.8 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 06 Mar 2012 11:25:59 +0000
From: "gjl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/52505] New: [avr]: __memx address space reading unintentionally from RAM
Date: Tue, 06 Mar 2012 11:26:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: gjl at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-52505-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2012-03/txt/msg00511.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52505

             Bug #: 52505
           Summary: [avr]: __memx address space reading unintentionally
                    from RAM
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: gjl@gcc.gnu.org
            Target: avr


The __memx address space reader must determine at runtime from what memory area
to read and what instruction to use. To read one byte, ine sequence might look
like:

    ld   r24,Z
    sbrs r25,7
    lpm  r24,Z

This is not correct because if the read is fram flash memory but the address
taken as RAM address points to the I/O area, the read might have an effect on
I/O register, for example clear a latch or buffer.