Karim BELABAS on Thu, 15 May 2003 16:53:38 +0200 (MEST)

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[Cygwin] MPQS broken


  I have just received a bug report that MPQS is completely broken under
Cygwin, at least compiled with gcc-3.2 (that's my XP binary, as available
in parigp-home.de's download area :-(). I can reproduce it on our Windows
box (XP), and of course nowhere else.

Any invocation of mpqs(), e.g as in

  factor(2^(2^7) + 1)

causes a SEGV in mpqs.c:mpqs_mergesort_lp_file0(), more precisely in the first
fgets() [ line 400 ], within memcpy() in cygwin1.dll.

This only occurs with -fomit-frame-pointer, at -O2 or higher so it doesn't
look like cygwin1.dll is to blame. It's independant of GCC_INLINE and works
flawlessly at -O1, or without -fomit-frame-pointer.

I have absolutely no clue as to what could cause the bug. Just in case,
I have extended the size of some static arrays, e.g


to no avail. At least the bug doesn't go away when I add printf calls

Any idea ???

Karim Belabas                     Tel: (+33) (0)1 69 15 57 48
Dép. de Mathématiques, Bât. 425   Fax: (+33) (0)1 69 15 60 19
Université Paris-Sud              http://www.math.u-psud.fr/~belabas/
F-91405 Orsay (France)            http://www.parigp-home.de/  [PARI/GP]