x86_64: floating-point environment (i.e. fenv.h). BUG.

[Houder]

On 2018-08-01 13:00, Corinna Vinschen wrote:
> On Aug  1 12:22, Houder wrote:
>> Hi Corinna,
>> 
>> Short version of my report (as there is more to say about the 
>> implementation
>> of
>> "fenv") in Cygwin; this time I restrict myself to a bug in fegetenv() 
>> ).
>> 
>> (Note to myself: attach STC)
>> 
>> I am reporting a bug in fegetenv() in winsup/cygwin/fenv.cc. There is 
>> no
>> hurry
>> in repairing this bug, as "fenv" is hardly ever (never?) used by 
>> anyone.
>> 
>> fegetenv() should be modified as follows:
>> 
>> from:
>>   __asm__ volatile ("fnstenv %0" : "=m" (envp->_fpu) : );
>>   if (use_sse)
>>     __asm__ volatile ("stmxcsr %0" : "=m" (envp->_sse_mxcsr) : );
>>   return 0
>> 
>> to:
>> // Henri: copying glibc ...
>>   __asm__ volatile ("fnstenv %0\n"
>>                     "fldenv %0" : "=m" (envp->_fpu) : );
>>   if (use_sse)
>>     __asm__ volatile ("stmxcsr %0" : "=m" (envp->_sse_mxcsr) : );
>>   return 0;
> 
> Since you know how to fix things, please just send patches to
> the cygwin-patches ML.

Ah ... Agreed. However, as I am not set up for building (anymore), this
will take some time ... (not even git is installed).

(yes, I did verify the above modification (and more), however I did that
  "locally" (basically, I included winsup/cygwin/fenv.cc in my  STC) ).

Regards,

Henri

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