llvm dev - Aug 2008 - [LLVMdev] LoopPass Question

Are LoopPasses allowed to maintain state between runOnLoop invocations?
The documentation is not clear on this point.

                                                  -Dave

On Aug 19, 2008, at 12:32 PM, David Greene wrote:
> Are LoopPasses allowed to maintain state between runOnLoop  
> invocations?
What kind of information are you looking to maintain between runOnLoop  
invocations ?
>
> The documentation is not clear on this point.
doInitialization() and doFinalization() will be run for each pass  
before and after runOnLoop().

For each pass
   doInitialization()
For each pass
   runOnLoop()
For each pass
   doFinalization()

So each pass can collect information during initialization pass to use  
during runOnLoop().

-
Devang

On Tuesday 19 August 2008 15:15, Devang Patel wrote:
> On Aug 19, 2008, at 12:32 PM, David Greene wrote:
> > Are LoopPasses allowed to maintain state between runOnLoop
> > invocations?
>
> What kind of information are you looking to maintain between runOnLoop
> invocations ?
Cached analysis answers.
> > The documentation is not clear on this point.
>
> doInitialization() and doFinalization() will be run for each pass
> before and after runOnLoop().
>
> For each pass
>    doInitialization()
> For each pass
>    runOnLoop()
> For each pass
>    doFinalization()
>
> So each pass can collect information during initialization pass to use
> during runOnLoop().
runOnLoop computes some information about basic blocks.  I would like
to reuse that information in later runOnLoop invocations.  Is the loop pass
created and destroyed for each invocation?

                                                   -Dave