Re: optimization/10185: [3.3/3.4 regression] Wrong code with 3-int-structs & optimization

[bangerth@dealii.org]

Old Synopsis: Wrong code with 3-int-structs & optimization
New Synopsis: [3.3/3.4 regression] Wrong code with 3-int-structs & optimization

State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Fri Mar 21 15:40:24 2003
State-Changed-Why:
    Confirmed, a regression on 3.3 and mainline w.r.t. 3.2.2.
    Here's a slightly simpler code:
    --------------------
    typedef struct {
      int x1, dummy1, dummy2;
    } X;
    
    void barrier (int *dummy) {}
    
    main ()
    {
      static X x[] = {{1}, {2}, {5}};
      int i=3, flag=0;
    
      barrier(&i);
      
      while (i--)
        if (x[i].x1 == 2)  // should trigger for i==1
          flag = 1;
      
      if (flag != 1)
        abort ();
    }
    -------------------------------
    The abort() shouldn't be triggered, but is if compiled 
    with -O2 in 3.3 and mainline:
    
    g/x> /home/bangerth/bin/gcc-3.2.2-pre/bin/gcc -O2 x.c ; ./a.out
    g/x> /home/bangerth/bin/gcc-3.3-pre/bin/gcc -O2 x.c ; ./a.out
    Aborted
    g/x> /home/bangerth/bin/gcc-3.4-pre/bin/gcc -O2 x.c ; ./a.out
    Aborted
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10185