Re: Test results for m4-1.4.9b

[Gary V. Vaughan]

Hi Bruno,

On 5 Jun 2007, at 00:06, Bruno Haible wrote:
> > That fixes test-frexpl.c on my ppc machine.
>
> OK, I've committed the fix.

My bad, I meant test-printf-frexpl is fixed by the patch.  I'm  
talking about
the Mac OS X ppc test-frexpl failure below.  Committing the whole fix  
was
still the right thing to do though.  Sorry for the confusion.

> > the loop aborts in an assertion failure on the first iteration:
>
> Hmm, both mantissa and x appear rounded to 'double' precision but  
> in different
> rounding directions. This is still not conclusive. Maybe gdb cannot  
> print
> the 'long double's correctly?
>
> Can you insert printf %LA statements for mantissa and x, as well as  
> for
> 1.01L and 0.505L, instead of relying on gdb? (You see, I don't  
> trust gdb,
> and I don't even trust the constant numbers.) Also, is the frexpl()  
> function
> from MacOS X or is it gnulib's? What we need in the end is a small  
> testcase
> program for the autoconf test.

(This is using test-frexpl.c from gnulib HEAD after your patch commit)

    1.01L = 0X2.051EB851EB851EB851EB851EB8P-1
   0.505L = 0X2.051EB851EB851EB851EB851EB8P-2

 mantissa = 0X2.051EB851EB851EB851EB851EB8P-2
        x = 0X2.051EB851EB851EB851EB851EB8P-1
 mantissa == 0.505L? no
 test-frexpl.c:171: assertion failed
 FAIL: test-frexpl

Hrmm, the bit patterns look identical to me.  I'm lost!

 $ ls -l lib/fre*
  4 -rw-r--r-- 1 gary gary  1744 May 30 02:37 lib/freading.c
  4 -rw-r--r-- 1 gary gary  1869 May 30 02:37 lib/freading.h
 12 -rw-r--r-- 1 gary gary 12184 Jun  4 16:05 lib/freading.o
  4 -rw-r--r-- 1 gary gary   973 Mar 23 12:50 lib/free.c
  4 -rw-r--r-- 1 gary gary  3920 May 30 02:37 lib/frexp.c
  4 -rw-r--r-- 1 gary gary   854 May 30 02:37 lib/frexpl.c

Gnulib's frexp* have not been compiled, so it seems that autoconf has  
decided
that the MacOS ppc implementation is good enough... for completeness'  
sake:

 $ ./configure --enable-changeword gl_cv_func_frexpl_works=no
 ...
 checking whether frexpl() can be used without linking with libm... yes
 checking whether frexpl works... (cached) no
 ...
 $ ls -l lib/fre*
 4 -rw-r--r-- 1 gary gary 1744 May 30 02:37 lib/freading.c
 4 -rw-r--r-- 1 gary gary 1869 May 30 02:37 lib/freading.h
 4 -rw-r--r-- 1 gary gary 2044 Jun  5 11:40 lib/freading.o
 4 -rw-r--r-- 1 gary gary  973 Mar 23 12:50 lib/free.c
 4 -rw-r--r-- 1 gary gary 3920 May 30 02:37 lib/frexp.c
 4 -rw-r--r-- 1 gary gary  854 May 30 02:37 lib/frexpl.c
 8 -rw-r--r-- 1 gary gary 4668 Jun  5 11:40 lib/frexpl.o
 $ make all check
 ...
    1.01L = 0X2.051EB851EB851EB851EB851EB8P-1
   0.505L = 0X2.051EB851EB851EB851EB851EB8P-2

 mantissa = 0X2.051EB851EB851EB851EB851EB8P-2
        x = 0X2.051EB851EB851EB851EB851EB8P-1
 mantissa == 0.505L? yes
 ...
 mantissa = 0X2.051EB851EB851EB851EB851EB8P-2
        x = 0X2.051EB851EB851EB851EB851EB8P+1021
 mantissa == 0.505L? yes

 mantissa = 0X2.051EB851EB851EB851EB851EB8P-2
        x = 0X2.051EB851EB851EB851EB851EB8P+1022
 mantissa == 0.505L? yes
 PASS: test-frexpl
 ...
 All checks successful

Cheers,
        Gary
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