Patch for jump optimization

[Jeffrey A Law]

  In message < Pine.OSF.3.96.980202225739.10800A-100000@ylws34 >you write:
  > On alpha-dec-osf4.0, the current egcs in the cvs tree fails to build
  > libgcc2.a, because the jump optimization (modified_in_p) fails to
  > process the following insn.
  > 
  > (jump_insn 52 51 54 (set (pc)
  >         (if_then_else (eq (reg:DI 102)
  >                 (const_int 0))
  >             (label_ref 56)
  >             (pc))) 178 {umindi3+2} (nil)
  >     (nil))
  > 
  > I use the following patch to get the bootstrap going.
  > 
  > Mon Feb  2 1998 11:00:20  Weiwen Liu <weiwen.liu@yale.edu>
  > 	* rtlanal.c (modified_in_p): Do not check modified_in_p if
  > 	XEXP (x, i) is NULL.
What field number was NULL (ie, what is the value of 'i' when it failed)?

The real bug might be elsewhere...

jeff