Re: Test results for m4-1.4.9b

[Gary V. Vaughan]

Hi Bruno,

On 4 Jun 2007, at 12:42, Bruno Haible wrote:
> Gary V. Vaughan wrote:
> > Run till exit from #0 my_ldexp  
> > (x=1.0121050218045312617883299999606451e-292, d=969) at test- 
> > printf- frexpl.c:56
>
> This value x has the mantissa 0x2.051EB851EB8520000000000000. Which
> means, the hardware truncates the precision when converting a  
> number from
> normalized to denormalized range.
>
> Can you try this patch, please? (Not yet committed in CVS.)
>
>
> *** tests/test-printf-frexpl.c  29 Apr 2007 09:15:13 -0000      1.4
> --- tests/test-printf-frexpl.c  4 Jun 2007 11:41:57 -0000
> ***************
> *** 39,49 ****
>     while (0)
>
>   /* On MIPS IRIX machines, LDBL_MIN_EXP is -1021, but the smallest  
> reliable
> !    exponent for 'long double' is -964.  For exponents below that,  
> the
> !    precision may be truncated to the precision used for  
> 'double'.  */
>   #ifdef __sgi
>   # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 57)
>   # define MIN_SUBNORMAL_EXP MIN_NORMAL_EXP
>   #else
>   # define MIN_NORMAL_EXP LDBL_MIN_EXP
>   # define MIN_SUBNORMAL_EXP (LDBL_MIN_EXP - 100)
> --- 39,54 ----
>     while (0)
>
>   /* On MIPS IRIX machines, LDBL_MIN_EXP is -1021, but the smallest  
> reliable
> !    exponent for 'long double' is -964.  Similarly, on PowerPC  
> machines,
> !    LDBL_MIN_EXP is -1021, but the smallest reliable exponent for  
> 'long double'
> !    is -968.  For exponents below that, the precision may be  
> truncated to the
> !    precision used for 'double'.  */
>   #ifdef __sgi
>   # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 57)
>   # define MIN_SUBNORMAL_EXP MIN_NORMAL_EXP
> + #elif defined __ppc || defined __ppc__ || defined __powerpc ||  
> defined __powerpc__
> + # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 53)
> + # define MIN_SUBNORMAL_EXP MIN_NORMAL_EXP
>   #else
>   # define MIN_NORMAL_EXP LDBL_MIN_EXP
>   # define MIN_SUBNORMAL_EXP (LDBL_MIN_EXP - 100)

That fixes test-frexpl.c on my ppc machine.

> *** tests/test-frexpl.c 29 Apr 2007 09:15:13 -0000      1.6
> --- tests/test-frexpl.c 4 Jun 2007 11:41:57 -0000
> ***************
> *** 40,49 ****
>     while (0)
>
>   /* On MIPS IRIX machines, LDBL_MIN_EXP is -1021, but the smallest  
> reliable
> !    exponent for 'long double' is -964.  For exponents below that,  
> the
> !    precision may be truncated to the precision used for  
> 'double'.  */
>   #ifdef __sgi
>   # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 57)
>   #else
>   # define MIN_NORMAL_EXP LDBL_MIN_EXP
>   #endif
> --- 40,53 ----
>     while (0)
>
>   /* On MIPS IRIX machines, LDBL_MIN_EXP is -1021, but the smallest  
> reliable
> !    exponent for 'long double' is -964.  Similarly, on PowerPC  
> machines,
> !    LDBL_MIN_EXP is -1021, but the smallest reliable exponent for  
> 'long double'
> !    is -968.  For exponents below that, the precision may be  
> truncated to the
> !    precision used for 'double'.  */
>   #ifdef __sgi
>   # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 57)
> + #elif defined __ppc || defined __ppc__ || defined __powerpc ||  
> defined __powerpc__
> + # define MIN_NORMAL_EXP (LDBL_MIN_EXP + 53)
>   #else
>   # define MIN_NORMAL_EXP LDBL_MIN_EXP
>   #endif

This doesn't have chance to come into play, as the loop aborts in an  
assertion
failure on the first iteration:

(gdb) run
Starting program: /Users/gary/m4-1.4.9b/tests/test-frexpl

Breakpoint 1, main () at test-frexpl.c:160
160       for (i = 1, x = 1.01L; i <= LDBL_MAX_EXP; i++, x *= 2.0L)
(gdb) n
162           int exp = -9999;
(gdb)
163           long double mantissa = frexpl (x, &exp);
(gdb)
164           ASSERT (exp == i);
(gdb)
165           ASSERT (mantissa == 0.505L);
(gdb) p mantissa
$1 = 0.50499999999999989341858963598497212
(gdb) p exp
$2 = 1
(gdb) p i
$3 = 1
(gdb) p x
$4 = 1.0100000000000000088817841970012523
(gdb) n
test-frexpl.c:165: assertion failed

Program received signal SIGABRT, Aborted.
0x9004822c in kill ()

Cheers,
        Gary
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