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Re: Failure of default_format_1.f90
- From: FX Coudert <fxcoudert at gmail dot com>
- To: Steve Kargl <sgk at troutmask dot apl dot washington dot edu>
- Cc: fortran at gcc dot gnu dot org
- Date: Wed, 3 Oct 2007 21:36:40 +0100
- Subject: Re: Failure of default_format_1.f90
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- References: <20071003194221.GA11216@troutmask.apl.washington.edu>
It appears that either your testcase is bogus or (as I feared)
you broke gfortran cratering to the darwin platform.
I have not committed any patch addressing a darwin issue (except
xfailing two testcases after having shown that darwin system
libraries were broken; see below). Please refrain from
unsubstantiated claims, as it's really counterproductive (and, on
this occasion, doesn't give me ). I have already said I do understand
your concerns that maintainability is a key element in evaluating
bugs and patches, and I'll stick to it. You can review the patch that
caused this, and tell me how it burdens maintainance:
2007年10月02日 Francois-Xavier Coudert <fxcoudert@gcc.gnu.org>
PR fortran/33469
* io/write.c (write_real): Widen the default formats.
--- trunk/libgfortran/io/write.c 2007年10月02日 20:56:47 128966
+++ trunk/libgfortran/io/write.c 2007年10月02日 23:27:51 128967
@@ -698,18 +698,18 @@
switch (length)
{
case 4:
- f.u.real.w = 14;
- f.u.real.d = 7;
+ f.u.real.w = 15;
+ f.u.real.d = 8;
f.u.real.e = 2;
break;
case 8:
- f.u.real.w = 23;
- f.u.real.d = 15;
+ f.u.real.w = 25;
+ f.u.real.d = 17;
f.u.real.e = 3;
break;
case 10:
- f.u.real.w = 28;
- f.u.real.d = 19;
+ f.u.real.w = 29;
+ f.u.real.d = 20;
f.u.real.e = 4;
break;
case 16:
As for the failure, you don't say which target you're talking about,
but I take it to be x86_64-freebsd. That means that writing denormals
and reading them back doesn't yield the same value. Now, this could
be because the field is not large enough, but then it'd be a generic
x86 failure, no freebsd specific (testcase works fine on x86_64-
linux). So, it's probably a problem with freebsd's printf().
$ cat u.f90
program p
real(kind=8) :: x, y
character(len=100) :: s
print '(I0,1X,I0)', digits(1.d0), precision(1.d0)
x = tiny(x)
write (s,*) x
read (s,*) y
print *, x
print *, y
x = 2.22507385850710603d-308
write (s,*) x
read (s,*) y
print *, x
print *, y
end program p
$ gfortran u.f90 && ./a.out
53 15
2.22507385850720138E-308
2.22507385850720138E-308
2.22507385850710603E-308
2.22507385850710603E-308
I've already seen such failures on Darwin (both ppc and x86) and have
thus xfail'ed this testcase there, I can add freebsd to that xfail
target list. Or, I could just tweak the testcase not to test
denormals (patch provided below), but I think there's no reason to
treat them separately.
Index: default_format_1.f90
===================================================================
--- default_format_1.f90 (revision 128992)
+++ default_format_1.f90 (working copy)
@@ -86,15 +86,15 @@ program main
if (test (1.0_4, 0) /= 0) call abort
if (test (0.0_4, 0) /= 0) call abort
- if (test (tiny(0.0_4), 0) /= 0) call abort
- if (test (-tiny(0.0_4), 0) /= 0) call abort
+ if (test (tiny(0.0_4), 1) /= 0) call abort
+ if (test (-tiny(0.0_4), -1) /= 0) call abort
if (test (huge(0.0_4), -1) /= 0) call abort
if (test (-huge(0.0_4), 1) /= 0) call abort
if (test (1.0_8, 0) /= 0) call abort
if (test (0.0_8, 0) /= 0) call abort
- if (test (tiny(0.0_8), 0) /= 0) call abort
- if (test (-tiny(0.0_8), 0) /= 0) call abort
+ if (test (tiny(0.0_8), 1) /= 0) call abort
+ if (test (-tiny(0.0_8), -1) /= 0) call abort
if (test (huge(0.0_8), -1) /= 0) call abort
if (test (-huge(0.0_8), 1) /= 0) call abort
Index: default_format_2.f90
===================================================================
--- default_format_2.f90 (revision 128992)
+++ default_format_2.f90 (working copy)
@@ -56,8 +56,8 @@ program main
if (test (1.0_kl, 0) /= 0) call abort
if (test (0.0_kl, 0) /= 0) call abort
- if (test (tiny(0.0_kl), 0) /= 0) call abort
- if (test (-tiny(0.0_kl), 0) /= 0) call abort
+ if (test (tiny(0.0_kl), 1) /= 0) call abort
+ if (test (-tiny(0.0_kl), -1) /= 0) call abort
if (test (huge(0.0_kl), -1) /= 0) call abort
if (test (-huge(0.0_kl), 1) /= 0) call abort
x = 2.22507385850710603E-308
trim(s) = 2.22507385850710603E-308
y = 2.22507385850710652E-308
program p
print '(I0,1X,I0)', digits(1.d0), precision(1.d0)
end program p
troutmask:sgk[243] gfc4x -o z p.f90
troutmask:sgk[244] ./z
53 15
1 23456789012345
2.22507385850710652E-308
^^^
There are garbage.
One can either check /usr/include/float.h of the expected
number of decimal digits or use real_info->precision to
determine a desirable value.
A desirable value for what? That paragraph leaves me quite puzzled.
Regards,
FX