[LTO] patch: new CALL_EXPR abstractions in builtins.c

[Paolo Bonzini]

> [huge snip]
>   
(because for a full reply I need to do some experiments and read some code)
> Didn't I make a good catch in the review/suggestion?
>   
 From the incremental point of view, sure you did.

On the other hand, I was running (too?) fast and trying to see the 
picture at the end of Sandra's work.  My understanding was that instead 
of speculatively building an arglist and a CALL_EXPR, she'd end up 
building the CALL_EXPR directly with the arglist embedded into it: thus 
the break-even analysis in my first reply.

Of course, maybe this understanding is true, maybe it's not.  Sandra 
obviously knows better what she is doing, so if she accepted your 
suggestion, I guess it also fits in her big picture.  However, I do 
think that it would have been better to present a more complete plan of 
the work, that experienced people in this area of the compiler could 
evaluate, with approximate estimation of the memory usage at each step.  
Note that I'm not at all dismissing CodeSourcery's attempt to clean up 
TREE_CHAIN etc. as part of the LTO effort.

Paolo