BCT optimization

[Joern Rennecke]

> Joern> Could you elaborate what you mean with an 'empty RTX' ?
> 
> 	I mean an uninitialized RTX.  The pattern would have to initialize

How do you allocate it?  The gen_rtx* function also initialize.

> it.  The BCT optimization would call gen_decrement_and_branch_init() with
> an RTX that was uninitialized.  The pattern would know this and initialize
> that operand[] with gen_rtx_REG() or GEN_INT() whatever cookie it wanted
> to hand back.

gen_rtx_REG and GEN_INT allocate, so that is no way to initialize
an uninitialized RTX.