[LLVMdev] mem2reg optimization

[Chris Lattner]

On Oct 26, 2008, at 11:09 PM, Chris Lattner wrote:
>> Fundamentally, we need a map from BasicBlock to a list of ordered
>> loads and
>> stores in that block.
>
> Are you seeing cases where lots of time is spent in
> RewriteSingleStoreAlloca[s]?  If so, please provide a testcase and I
> can apply the obvious fix.

Okay, I decided to just go ahead and make the change, with the  
justification that it is a significant code cleanup to mem2reg.   
Here's the patch:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20081027/068970.html

Are there any other places which exhibit bad behavior with large  
blocks in mem2reg?  I see a linear scan over instructions in  
RenamePass.  If you can produce a testcase which shows a problem  
there, I'd be happy to help fix it.

-Chris