But in gcc targeting ultrasparc.

[David Koppelman]

I've found that code compiled by gcc 2.95 encounters a segmentation
fault or bus error when targeting the ultrasparc.  Code to reproduce
the bug and a transcript of commands appears below.

__
      /\                                /\                              /\
      <>                                <>  David M. Koppelman          <>
      <>             koppel@ee.lsu.edu  <>  Electrical & Computer Eng.  <>
      <>             +1 (225) 578-5482  <>  Louisiana State University  <>
      <>  http://www.ee.lsu.edu/koppel  <>  Baton Rouge, La 70803, USA  <>
      ~~                                ~~                              ~~




#if 0

Program encountering bug in gcc targeting the ultrasparc.

Reported by David M. Koppelman, koppel@ee.lsu.edu


[sol] % uname -a
SunOS sol 5.6 Generic_105181-20 sun4u sparc SUNW,Ultra-Enterprise
[sol] % gcc -v
Reading specs from /opt/local/lib/gcc-lib/sparc-sun-solaris2.6/2.95.2/specs
gcc version 2.95.2 19991024 (release)
[sol] % gcc test.c -S -O3 -mcpu=ultrasparc -g
[sol] % gcc test.s -o test -mcpu=ultrasparc -g -lm
[sol] % test
Bus error
[sol] % 

The resulting code uses std instructions with unaligned addresses when writing
values to pass to fprintf.  Here is the offending assembler output:


.LLM22:
	st	%f2, [%fp-16]
	ld	[%fp-16], %g2
	st	%f3, [%sp+92]
	mov	%g2, %o5
	std	%f2, [%fp-16]
	ldd	[%fp-16], %g2
	std	%f2, [%sp+96]
	mov	%g2, %o3
	mov	%g3, %o4
	std	%f2, [%fp-184]
	call	fprintf, 0
	std	%f2, [%sp+108]    <-  Unaligned
.stabn 68,0,33,.LLM23-main
.LLM23:


#endif


#include <stdio.h>
#include <math.h>

int
main(argv, argc)
     int argv;
     char **argc;
{

  double vals[] = { 0.29981156741642356663, 0.06534463297941150939, 
                    0.08700884626263230268, 0.29481898613027235343,
                    0.40327876077409174349, 0.64313111626589508526, 
                    0.87204040650558993179, 0.77195657231840326457, 
                    0.84440588988184180826, 0.23206499454819179893, 0};

  double results[] = { 1.356199986544775, 0.644148072499925, 0.286979564536114, 
                       0.631265700663381, 0.560075902893138, 0.635453970629484, 
                       0.846201478113202, 0.740605699133083, 1.302591557566638 };

  double *rp = &results[0];

  double *vp = &vals[0];

  int err_count1 = 0;
  int err_count2 = 0;
  while ( *++vp != 0 ) 
    {
      double diff = atan2(vp[-1],vp[0]) - *rp++;

      fprintf(stdout," %d %.16f, %f %f %d %f ",
              err_count1,diff,diff,diff,err_count1,diff);
      if( diff > 1e-15 ) err_count1++;
      if( diff < -1e-15 ) err_count2++;
    }
    /*  printf("%.15f, ", atan2(vp[-1],vp[0]) );  */

  if( err_count1 + err_count2 ) printf("\nErrors found %d %d\n",
                                       err_count1,err_count2);
  
  return 0;
}