From mboxrd@z Thu Jan  1 00:00:00 1970
From: sebor@roguewave.com
To: gcc-gnats@gcc.gnu.org
Subject: optimization/4371: gcc 3.0.1 optimization introduces an infinite loop
Date: Thu, 20 Sep 2001 15:06:00 -0000
Message-id: <20010920220024.13036.qmail@sourceware.cygnus.com>
X-SW-Source: 2001-09/msg00429.html
List-Id: <gcc-prs.sourceware.org>

>Number:         4371
>Category:       optimization
>Synopsis:       gcc 3.0.1 optimization introduces an infinite loop
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 20 15:06:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     sebor@roguewave.com
>Release:        gcc 3.0.1
>Organization:
>Environment:

>Description:
The 3.0.1 optimizer incorrectly assumes that (i - 1 < i)
will always hold for all i's of type int (or any signed
type for that matter). The code is derived from a test
that computes the values of integral limits. The problem
exists in prior versions of gcc as well.

Regards
Martin
>How-To-Repeat:
$ cat t.c ; gcc -O -S t.c && cat t.s
int main ()
{
    int i = -2147483647;

    for (; i - 1 < i; i -= 1);
}
        .file   "t.c"
        .version        "01.01"
        .text
        .align 4
.globl main
        .type   main,@function
main:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $8, %esp
        andl    $-16, %esp
        .align 4
.L4:
        jmp     .L4
.Lfe1:
        .size   main,.Lfe1-main
        .ident  "GCC: (GNU) 3.0.1"
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: