Patch for jump optimization

[Weiwen Liu]

On Tue, 3 Feb 1998, Jeffrey A Law wrote:

> 
>   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
> 

When i is 6, XEXP (x, 6) = (nil)