egcs 1.1.2 (egcs-2.91.66) bug report (core dump with -O, -O2 option)

[Aki Niimura]

Hi,

This is the same as I sent. However, previously I sent this in HTML format
which might be inconvenient to some people. This time I'm sending this
in plain text.
Aki-

//

g++ bug report

Reporter : Aki Niimura  neko@my-dejanews.com
Date : 03/30/99 

g++ version : egcs 1.1.2 (egcs-2.91.66)
Environment :
% uname -a
SunOS Evelyn 5.7 Generic sun4m sparc SUNW,SPARCstation-4 

Bug description :
The attached program runs correctly *if* compiled with no
optimization. But it will core dump if compiled with
optimization option (-O, -O2).
Although I haven't confirmed, this bug seems also in the
previous releases.
I have tried to de-mystify this, but I couldn't figure out
what exactly the problem is. 

// a session log

% g++ test.cc
% aout
a.out
a @0
b @10
c @20
a @21
% g++ -O test.cc
% a.out
a @0
b @10
Segmentation Fault (core dumped)   <<===
% g++ -O2 test.cc
% a.out
a @0
b @10
Segmentation Fault (core dumped)   <<===
% 

// gdb log
%gdb a.out  (compiled with -O) 
..... 
(gdb) run
Starting program: /export/home/neko/tmp/a.out
a @0
b @10 

Program received signal SIGSEGV, Segmentation fault.
0x1a470 in T::test (this=20, _f=false) at test.cc:35
35  if($time < $till) return;
(gdb)  

// A test program which can reproduce this bug

      1 #include <iostream.h>
      2 #include <setjmp.h>
      3
      4
      5 int $time;
      6
      7 class T {
      8 public:
      9     T() { };           
     10
     11     void test(bool _f);
     12 };
     13
     14 void
     15 T::test(bool _f)
     16 {
     17     static bool _f2 = false;
     18     static jmp_buf $env;
     19     static int $till;
     20
     21     if(_f) { _f2 = false; return; }
     22
     23     if(_f2) longjmp($env, 1);
     24     else _f2 = true;
     25
     26     cout << "a @" << $time << endl;
     27
     28     $till = $time+10;
     29     if(setjmp($env) == 0) return;
     30     if($time < $till) return;
     31     cout << "b @" << $time << endl;
     32
     33     $till = $time+10;
     34     if(setjmp($env) == 0) return;
     35     if($time < $till) return;
     36     cout << "c @" << $time << endl;
     37
     38     _f2 = false;
     39 }
     40
     41 main()
     42 {
     43     T test;
     44
     45     $time = 0;
     46     test.test(true);
     47     for(int i = 0; i < 25; ++i, ++$time)    test.test(false);
     48 }
     49