other/6613: Problem with RTX_UNCHANGING_P (again)

other/6613: Problem with RTX_UNCHANGING_P (again)

[jching]

>Number:         6613
>Category:       other
>Synopsis:       Problem with RTX_UNCHANGING_P (again)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu May 09 13:46:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     jching@flex.com
>Release:        Verified on 3.1, 3.0.4, 3.0.2 20011002 by Jakub Jelinek
>Organization:
>Environment:
Debian/GNU-Linux IA-32, gcc 3.1
>Description:
The code below produces garbage.

But compiling without -O2 or with -DREMOVE_CTOR or -DUSE_INT
will work-around the problem.

--jc
----------------------------
#include <iostream>

struct logic
        {
        enum state_value { LO, HI, DC, Z, NVL };

        logic(state_value l = NVL)
                : state(l) { }
#ifndef REMOVE_CTOR
        logic(const logic &l)
                : state(l.state) { }
#endif

#ifdef USE_INT
        int state;
#else
        char state;
#endif
        };

const logic  LO(logic::LO);
const logic  HI(logic::HI);

void func(void);

int
main()
        {
        func();
        return 0;
        }

struct addtab
        {
        logic sum;
        logic carry;
        };
const struct addtab ADDTABLE[] =
        {
        {LO,LO},
        {HI,LO},
        {HI,LO},
        {LO,HI},
        {HI,LO},
        {LO,HI},
        {LO,HI},
        {HI,HI}
        };

void
func(void)
        {
        for (int tmp = 0; tmp < 8; ++tmp)
                {
                std::cout << (int)ADDTABLE[tmp].sum.state
                          << ","
                          << (int)ADDTABLE[tmp].carry.state
                          << std::endl;
                }
        }

>How-To-Repeat:
g++ -O2 file.cc
>Fix:

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

Re: other/6613: Problem with RTX_UNCHANGING_P (again)

[mmitchel]

Synopsis: Problem with RTX_UNCHANGING_P (again)

State-Changed-From-To: analyzed->closed
State-Changed-By: mmitchel
State-Changed-When: Thu Oct 17 13:57:18 2002
State-Changed-Why:
    Already fixed in GCC 3.2.1.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6613

Re: other/6613: Problem with RTX_UNCHANGING_P (again)

[jakub]

Synopsis: Problem with RTX_UNCHANGING_P (again)

State-Changed-From-To: open->analyzed
State-Changed-By: jakub
State-Changed-When: Mon May 13 00:03:20 2002
State-Changed-Why:
    Simplified testcase is
    struct L
    {
      enum S { A, B, C };
      L (S x = C) : l (x) {}
      L (const L &x) : l (x.l) {}
      char l;
    };
    
    const L A (L::A);
    const L B (L::B);
    
    struct T
    {
      L u, v;
    };
    
    const struct T x [] =
    {
      {A, A}, {B, A}, {B, A}, {A, B}, {B, A}, {A, B}, {A, B}, {B, B}
    };
    
    extern "C" void abort (void);
    extern "C" void exit (int);
    
    int
    main()
    {
      for (int i = 0; i < 8; i++)
        {
          if (x[i].u.l * 2 != ((((i & 3) ^ (i >> 2)) + 1) & 2))
            abort ();
          if (x[i].v.l != ((((i + 1) ^ 1) - 1) >= 4))
            abort ();
        }
      exit (0);
    }
    
    Regression from 2.95.x.
    
    For some details, see http://gcc.gnu.org/ml/gcc/2002-05/msg00642.html

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6613