Date: Sat, 27 Mar 93 07:54:31 MST
From: bob AT plk DOT af DOT mil (Bob Conley)
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Runtime error in gcc


I have been using the djgpp MS-DOS port of GNU C for about a month, with
good results.  Recently I have uncovered what appears to be a problem with
the compiler itself.  I am new to the world of GNU C, so I am not sure if
this is the appropriate manner to report a bug, but the following is submitted
in the hope that whomever should review it will ultimately receive it.

This occurs with version 2.22 of gcc;  I have been unable to access the
"barnacle" machine to verify that this is still the current version.

The C procedure below triggers an execution error in gcc itself when compiled
with the following command line (assuming the C procedure is placed in file
"test.c"):

     gcc -O -c test.c

The following error messages are emitted, and gcc aborts execution:

     Segmentation violation in pointer 0x0000006a at 40:5abdb
     Exception 14 (0xe) at eip=5abdb

The error is not generated if the "-O" flag is not used;  if the "-O" is used,
the error is not generated if the list of "if( ... break; }" lines is
shortened by one line.  Nor is the error triggered if the entire structure
recoded in a more conventional "if...then...else if" form.

Here is the code which triggers the error;  copy it to file test.c and
execute the compiler command line shown above:

void Procedure (v)
int v;
{
  int rc;

  while (1)
   {
    if (v <   2) { rc =  0; break; }
    if (v <   3) { rc =  1; break; }
    if (v <   5) { rc =  2; break; }
    if (v <   7) { rc =  3; break; }
    if (v <  11) { rc =  4; break; }
    if (v <  13) { rc =  5; break; }
    if (v <  17) { rc =  6; break; }
    if (v <  19) { rc =  7; break; }
    if (v <  23) { rc =  8; break; }
    if (v <  29) { rc =  9; break; }
    if (v <  31) { rc = 10; break; }
    if (v <  37) { rc = 11; break; }
    if (v <  41) { rc = 12; break; }
    if (v <  43) { rc = 13; break; }
   }

}


  Bob Conley
  (505) 281-3354 (home)
  (505) 846-4844 (work)
  conley AT plk DOT af DOT mil