[LLVMdev] RegAllocFast uses too much stack

[Jakob Stoklund Olesen]

On Jul 11, 2011, at 3:43 PM, Eric Christopher wrote:

> 
> On Jul 11, 2011, at 3:41 PM, Dan Gohman wrote:
> 
>> On Jul 11, 2011, at 3:06 PM, Eli Friedman wrote:
>> 
>>> On Mon, Jul 11, 2011 at 2:44 PM, Eric Christopher <echristo at apple.com> wrote:
>>>> 
>>>> On Jul 11, 2011, at 1:48 PM, Nick Lewycky wrote:
>>>> 
>>>> This seems odd. I'd think that fast-isel should be able to materialize the constants when we want them rather than at the beginning of the block.
>>> 
>>> I'm not entirely sure why, but FastISel does intentionally materialize
>>> constants at the beginning of the block.  See
>>> FastISel::enterLocalValueArea etc.  Maybe Dan knows why?
>> 
>> 
>> Going bottom-up, FastISel doesn't know when it'll see the first use of a value
>> in a block. Cleverer schemes are possible.
> 
> Or less clever by not caching the result? :)

At least, we shouldn't cache stuff across function calls.

/jakob