Re: target/10194: [3.2 regression] [arm] gcc optimization error with -O2, affecting bison - Testcase found

["Stan Katz" <Stan dot Katz at ctc-control dot com>]

I have also recently run into this error, however it was not in one of the GNU packages and I managed to develop a small testcase that does cause the error (included within the email below), I am sending this, even though the bug is marked as closed, since it does provide a simple testcase for the problem.

the command line with compiler flags is

arm-elf-gcc -c -gdwarf-23 -O2 -mcpu=arm7tdmi -Wall  -c -o testarm.o ../src/testarm.c

If you set the ARMFAIL macro to zero then there is no error, a non zero value generates the error

../src/testarm.c: In function `filename':
../src/testarm.c:46: Internal compiler error in arm_rtx_costs, at config/arm/arm.c:2810
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

The problem seems to be the test
	if ((entry % 100) / 10)

Which, although ugly, is valid C.  There is a simple work around for my problem, so I will not have to upgrade to a later compiler (and redo all my system regression testing). Not surprisingly, considering the error message and the file referenced, this doesn't happen with the sh-elf build of this version of the compiler.


Error 10194 Testcase:
// Test file for ARM compiler error

#define ARMFAIL 1  // generated compiler failure below when set to 1
/*
../src/testarm.c: In function `filename':
../src/testarm.c:46: Internal compiler error in arm_rtx_costs, at config/arm/arm.c:2810
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.
*/

void filename(unsigned char *shortname, unsigned int entry, int i)
{
  /* Name suffice is between 000 and 999, calculate this short file 
     name's numeric component.  */
  entry = entry % 1000; 

  if (entry / 100)
  {

      /* Build short name of the format xxxx~NNN.ext.  */            
      if (i>4) i = 4;
      shortname[i++] = '~';
      shortname[i++] = '0' + (entry / 100);
      shortname[i++] = '0' + ((entry % 100) / 10);
      shortname[i++] = '0'+ (entry % 10);
  }
#if ARMFAIL
  else if ((entry % 100) / 10)
#else // ARMFAIL = 0
  else if (entry > 10)
#endif // ARMFAIL
  {

      /* Build short name of the format xxxxx~NN.ext.  */            
      if (i>5) i = 5;
      shortname[i++] = '~';
      shortname[i++] = '0' + ((entry % 100) / 10);
      shortname[i++] = '0'+ (entry % 10);
  }
  else
  {

      /* Build short name of the format xxxxxx~N.ext.  */
      if (i>6) i = 6;
      shortname[i++] = '~';
      if ((entry % 10) == 0) entry++;
      shortname[i++] = '0'+ (entry % 10);
  }

  /* Set end of short string to NULL.   */
  shortname[11] = 0;
}