0003-Improve-VBEout-computation.patch

[Paolo Bonzini]

On 06/16/2010 07:19 PM, Maxim Kuvyrkov wrote:
> the patch consists of two parts:
>
> 1. the big open-ended comment that describes an unimplemented possible
> improvement; I assume this what you're referring to; and

Yes.

> 2. a smaller comment and 2 lines of code that implement a different
> improvement to VBEout computation that is in line with traditional
> algorithm and doesn't penalize speed.

Got it now. :)

I was confused by the

+	      sbitmap_intersection_of_succs (hoist_vbeout[bb->index],
+					     hoist_vbein, bb->index);

after the comment, which however is just the preexisting code moved into 
braces.

Regarding (2), I think it's fine.  Still wondering about one thing 
though: if an expression is available at the end of BB and computed in 
BB, it is fully redundant and it should be PRE's task to remove it, 
right?  Maybe you're hitting the problem that our RTL PRE is not cascading?

Paolo