From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-393218-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 8991 invoked by alias); 30 May 2012 10:35:05 -0000
Received: (qmail 8897 invoked by uid 22791); 30 May 2012 10:35:04 -0000
X-SWARE-Spam-Status: No, hits=-4.3 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED
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; Wed, 30 May 2012 10:34:51 +0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/53501] [4.5/4.6/4.7/4.8 Regression] scev introduces signed overflow
Date: Wed, 30 May 2012 10:55:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.5.4
X-Bugzilla-Changed-Fields:
Message-ID: <bug-53501-4-Ec6uWX5UY2@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-53501-4@http.gcc.gnu.org/bugzilla/>
References: <bug-53501-4@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: 2012-05/txt/msg02836.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53501

--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-05-30 10:34:50 UTC ---
It's my very best friend extract_muldiv that transforms
(int)((unsigned int) n.0_26 + 4294967295) * 2
to (int)(((unsigned int) n.0_26 + 2147483647) * 2) 

It is the folding of (int) (((unsigned int) n.0_26 + 2147483647) * 2) + 2
which is wrong and done by fold_plusminus_mult_expr.  Patch:

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 188004)
+++ gcc/fold-const.c    (working copy)
@@ -10045,12 +10045,12 @@ fold_binary_loc (location_t loc,
       /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
         same or one.  Make sure type is not saturating.
         fold_plusminus_mult_expr will re-associate.  */
-      if ((TREE_CODE (arg0) == MULT_EXPR
-          || TREE_CODE (arg1) == MULT_EXPR)
+      if ((TREE_CODE (op0) == MULT_EXPR
+          || TREE_CODE (op1) == MULT_EXPR)
          && !TYPE_SATURATING (type)
          && (!FLOAT_TYPE_P (type) || flag_associative_math))
         {
-         tree tem = fold_plusminus_mult_expr (loc, code, type, arg0, arg1);
+         tree tem = fold_plusminus_mult_expr (loc, code, type, op0, op1);
          if (tem)
            return tem;
        }

that will leave the expression unsimplified.