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Date: Wed, 04 Dec 2002 14:31:00 -0000
Message-ID: <20021204223158.25767.qmail@sources.redhat.com>
To: duchier@ps.uni-sb.de, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
  nobody@gcc.gnu.org
From: bangerth@dealii.org
Reply-To: bangerth@dealii.org, duchier@ps.uni-sb.de, gcc-bugs@gcc.gnu.org,
  gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Subject: Re: optimization/8634: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2
X-SW-Source: 2002-12/txt/msg00251.txt.bz2
List-Id: <gcc-prs.sourceware.org>

Old Synopsis: incorrect inlining of memcpy under -O2
New Synopsis: [3.2/3.3 regression] incorrect code for inlining of memcpy under -O2

State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Wed Dec  4 14:31:57 2002
State-Changed-Why:
    Confirmed. This program
    ----------------------------
    #include <stdio.h>
    #include <string.h>
    
    int main()
    {
      char* buffer = new char[8];
      const char head[8] = {
        'A', 'B', 'C', 'D',
        'E', 'F', 'G', 'H'
      };
      memcpy(buffer,head,8);
      for(int i=0;i<8;i++)
        printf ("[%u] = %c, %c\n", i, head[i], buffer[i]);
      return 0;
    }
    --------------------------------
    yields with 3.2.2pre, 3.3pre, and 2.95 respectively:
    
    tmp/g> /home/bangerth/bin/gcc-3.2.2-pre/bin/c++ -O2 bug.cc  &&  ./a.out
    [0] = A, A
    [1] = B,
    [2] = C,
    [3] = D,
    [4] = E, E
    [5] = F, F
    [6] = G, G
    [7] = H, H
    
    
    tmp/g> /home/bangerth/bin/gcc-3.3-pre/bin/c++ -O2 bug.cc  &&  ./a.out
    [0] = A, A
    [1] = B,
    [2] = C,
    [3] = D,
    [4] = E, E
    [5] = F, F
    [6] = G, G
    [7] = H, H
    
    
    tmp/g> c++ -O2 bug.cc  &&  ./a.out
    [0] = A, A
    [1] = B, B
    [2] = C, C
    [3] = D, D
    [4] = E, E
    [5] = F, F
    [6] = G, G
    [7] = H, H
    
    
    That seems like a regression.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8634