Re: ffs problem in windows64

2014-09-23 Thread Eliot Moss 

On 9/23/2014 8:47 AM, Paulo César Pereira de Andrade wrote:

   Hi,

   I am almost done porting https://savannah.gnu.org/projects/lightning
to cygwin and windows64 abi. But I found a problem with the ffs function.

   The test case is simple:

$ cat x.c
extern int ffs(int);
int main(void) {
long l = 0x8000;
int i = ffs((int)l);
return 0;
}

$ gcc -O0 -g3 x.c

$ ./a.exe
Segmentation fault (...)


WJFFM in 32 bit cygwin.

Regards -- Eliot Moss


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Re: ffs problem in windows64

2014-09-23 Thread Christian Franke 

Eliot Moss wrote:

On 9/23/2014 8:47 AM, Paulo César Pereira de Andrade wrote:

   Hi,

   I am almost done porting https://savannah.gnu.org/projects/lightning
to cygwin and windows64 abi. But I found a problem with the ffs 
function.


   The test case is simple:

$ cat x.c
extern int ffs(int);
int main(void) {
long l = 0x8000;
int i = ffs((int)l);
return 0;
}

$ gcc -O0 -g3 x.c

$ ./a.exe
Segmentation fault (...)


WJFFM in 32 bit cygwin.



It fails under 64 bit cygwin.

This segfaults if gcc -fno-builtin option is used:
  ffs(0x8000)

These work:
  ffs(0xc000)
  ffs(0x4000)

Likely a subtle problem in table based ffs() implementation in 
winsup/cygwin/syscalls.cc if only upper bit is set. The newlib version 
of ffs() works.


Christian


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Re: ffs problem in windows64

2014-09-23 Thread Christian Franke 

Christian Franke wrote:

This segfaults if gcc -fno-builtin option is used:
  ffs(0x8000)

These work:
  ffs(0xc000)
  ffs(0x4000)

Likely a subtle problem in table based ffs() implementation in 
winsup/cygwin/syscalls.cc if only upper bit is set. The newlib version 
of ffs() works.




https://cygwin.com/ml/cygwin-patches/2014-q3/msg00014.html


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