Q61621: Internal Compiler Error ‘@(#)newcode.c:1.87’ Line 551

Article: Q61621
Product(s): See article
Version(s): 6.00   | 6.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 | mspl13_c
Last Modified: 25-JUL-1990

The following sample code produces an internal compiler error when
compiled with /Oct (Default Optimization) option under large and
compact memory models:

   prog.c(18) : fatal error C1001: Internal Compiler Error
                (compiler file '@(#)newcode.c:1.87', line 551)
                Contact Microsoft Product Support Services

Sample Code
-----------

struct AREASTR
{
   int *getnum;
   int **ypos, **xpos, **varnum;
};

struct AREASTR *z;

// #pragma optimize("ct",off) Disabling optimizations for this function
//                            will work around problem.

// #pragma optimize("gct",on) Adding global optimization will also work
//                            around problem.
sample_func()
{
   int i,k,no;
   int count, tx, ty, tnum;

   if (k<= z->getnum[no] && z->varnum[no][k] == 1)
   {
      tnum = z->varnum[no][count];
      //compiler crashes here
      tx = z->xpos[no][count];
      ty = z->ypos[no][count];

      z->varnum[no][count] = z->varnum[no][k];
      z->xpos[no][count] = z->xpos[no][k];
      z->ypos[no][count] = z->ypos[no][k];

      z->varnum[no][k] = tnum;
      z->xpos[no][k] = tx;
      z->ypos[no][k] = ty;
   }
}

/* #pragma optimize("ct",on)  enable time optimizations  */

Placing the #pragma optimize("ct",off) in the code causes the compiler
to disable default optimizations, thus working around the problem.

If optimizations are really needed then they may be turned back on
with the #pragma optimize("ct",on).

Also, instead of turning off optimizations for the function you may
add global optimizations (/Og) to the default optimizations to work
around the problem.

Microsoft has confirmed this to be a problem with C version 6.00. We
are researching this problem and will post new information here as it
becomes available.