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Date: Tue, 26 Mar 2002 10:18:00 -0000
Message-ID: <20020326181850.15297.qmail@sources.redhat.com>
To: djohnson@osc.edu, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
  nobody@gcc.gnu.org
From: jakub@gcc.gnu.org
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  gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Subject: Re: c++/6056: ICE on legal code with when optimizations higher that -O (ia64 only)
X-SW-Source: 2002-03/txt/msg00994.txt.bz2
List-Id: <gcc-prs.sourceware.org>

Synopsis: ICE on legal code with when optimizations higher that -O (ia64 only)

State-Changed-From-To: open->analyzed
State-Changed-By: jakub
State-Changed-When: Tue Mar 26 10:18:49 2002
State-Changed-Why:
    It is actually code with undefined behaviour (because
    it does invalid type punning), but no matter what
    gcc probably shouldn't ICE on it.
    Simplified into:
    extern unsigned long d[];
    unsigned long foo (unsigned char *x, int y)
    {
      unsigned long a = 0, c = 0;
      unsigned short *e = (unsigned short *) &a;
      int i, b;
    
      for (i = 0; i < y; i++)
        c = (c << 1) ^ d[i & 3];
      if (i & 3) a ^= c;
    
      a *= 1879048201;
      e[0] += e[1];
      return a;
    }
    at -O2.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6056