From: <ams AT ludd DOT luth DOT se>
Message-Id: <200304301100.h3UB0RBW010425@speedy.ludd.luth.se>
Subject: Re: Yet another try on nan in strto{f,d,ld}
In-Reply-To: <9743-Mon28Apr2003063327+0300-eliz@elta.co.il> "from Eli Zaretskii
 at Apr 28, 2003 06:33:28 am"
To: djgpp-workers AT delorie DOT com
Date: Wed, 30 Apr 2003 13:00:27 +0200 (CEST)
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According to Eli Zaretskii:
> > From: <ams AT ludd DOT luth DOT se>
> > Date: Sun, 27 Apr 2003 19:03:09 +0200 (CEST)
> > 
> > Uhoh! That was run in WINDOZE 98. In plain DOZE I get SIGFPE. Is that
> > bad?
> 
> It's not good.  I think we should replace the FP assignment with an
> assignment of a long long, or with a memcpy, then.

From what I can see the problem is in printf(), not in any assignments
strtof() does.

I add

  /* Fault on FPU exception. */
  _control87(0, 0x3f);
  printf("FPU CW: 0x%08x.\n", _control87(0, 0));

to the start of main in t-strtof.c (renamed to tstrtof2.c) and when
run I get a crash

A:\>tstrtof2
FPU CW: 0x00000340.
float tests:
Exiting due to signal SIGFPE
Floating Point exception at eip=0000b9b1, x87 status=b1a0
eax=000917ac ebx=00092c2b ecx=0000000c edx=00090f40 esi=000918ad edi=00000006
ebp=0009171c esp=00091718 program=A:\TSTRTOF2.EXE
cs: sel=00bf  base=00116000  limit=0009ffff
ds: sel=00c7  base=00116000  limit=0009ffff
es: sel=00c7  base=00116000  limit=0009ffff
fs: sel=009f  base=000051d0  limit=0000ffff
gs: sel=00d7  base=00000000  limit=0010ffff
ss: sel=00c7  base=00116000  limit=0009ffff
App stack: [00092dc4..00012dc4]  Exceptn stack: [00012d44..00010e04]
 
Call frame traceback EIPs:
  0x0000b9b1 __modfl+33
  0x000090ed cvtl+417
  0x00008632 _doprnt+1774
  0x0000379e sprintf+46
  0x00001d49 main+189, file tstrtof2.c, line 141
  0x0000368c __crt1_startup+204
 
A:\>symify -o tstrtof2.sym tstrtof2.exe


A less complex example, nan_ass2.c:

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

int
main(void)
{
  double d;
  long double ld;

  /* Fault on FPU exception. */
  _control87(0, 0x3f);
  printf("FPU CW: 0x%08x.\n", _control87(0, 0));

  d = NAN;
  printf("d = %.20g.\n", d);
  ld = NAN;
  printf("ld = %.20Lg.\n", ld);

  return(EXIT_SUCCESS);
}

generates

A:\>nan_ass2
FPU CW: 0x00000340.
Exiting due to signal SIGFPE
Floating Point exception at eip=00007738, x87 status=c581
eax=00094581 ebx=00000014 ecx=00000000 edx=00001629 esi=00000014 edi=00011d94
ebp=00091cdc esp=000908b4 program=A:\NAN_ASS2.EXE
cs: sel=00bf  base=00116000  limit=0009ffff
ds: sel=00c7  base=00116000  limit=0009ffff
es: sel=00c7  base=00116000  limit=0009ffff
fs: sel=009f  base=000051d0  limit=0000ffff
gs: sel=00d7  base=00000000  limit=0010ffff
ss: sel=00c7  base=00116000  limit=0009ffff
App stack: [00091d94..00011d94]  Exceptn stack: [00011d14..0000fdd4]
 
Call frame traceback EIPs:
  0x00007738 _doprnt+1652
  0x00002c2c printf+28
  0x00001684 main+72, file nan_ass2.c, line 18
  0x00002bbc __crt1_startup+204
 
A:\>symify -o nan_ass2.sym nan_ass2.exe

One weird thing, line 18 is "ld = NAN;", but the crash was in
printf/_doprnt?


Right,

						MartinS