[LLVMdev] PR3707

[Jakub Staszak]

On Oct 12, 2009, at 2:27 AM, Chris Lattner wrote:

> On Oct 10, 2009, at 7:48 AM, Jakub Staszak wrote:
>
>> This patch fixes pr3707.
>
> Can you explain a little more what this does?  What is the intuition  
> behind disabling this optimization?

Oh, this patch is crap :( Sorry for this.

The problem is that we lack of optimization for case like:

loopto:
   %timeout.0 = phi i32 [ 2000, %loopto ], [ %timeout.0.ph,  
%loopto.outer ]

Then something like "%reg<def> = MOV 2000" is inserted into loopto  
block and executed every time. I haven't found any optimization which  
can handle this and move instruction into some outer block.

-- 
Jakub Staszak