[LLVMdev] RegisterAnalysisGroup

[Chris Lattner]

On Sep 14, 2007, at 1:43 PM, David Greene wrote:

> Can someone explain how RegisterPass and RegisterAnalysisGroup
> conspire to pick the right member of an analysis group when command- 
> line
> options dictate non-default implementations?
>
> For example, when I pass -anders-aa to opt, where in the code is  
> that option
> parsed and setNormalCtor called on the analysis group to change  
> from the
> default basicaa?

When basicaa registers itself as part of the analysis group, it uses:

   RegisterPass<BasicAliasAnalysis>
   X("basicaa", "Basic Alias Analysis (default AA impl)");

   // Declare that we implement the AliasAnalysis interface
   RegisterAnalysisGroup<AliasAnalysis, true> Y(X);

The "true" says that it is the default,

-Chris