[PATCH] New alias analysis for static global variables

[Sam Parker]

In http://reviews.llvm.org/D10059#197376, @hfinkel wrote:

> In http://reviews.llvm.org/D10059#197018, @samparker wrote:
>
> > http://llvm.org/docs/AliasAnalysis.html#limitations
>
>
> That's a bit misleading. You can preserve underlying AA passes (although not the AliasAnalysis analysis group itself). The problems is that if *any* pass does not preserve it, it will be invalidated, and nothing will cause it to be regenerated (unless it is inserted again specifically in the pass manager).
>
> The question here is: Do we have *any* passes in-tree that would not preserve the cache trivially?


I'm not sure I follow. The immutable AA passes have no state so how are they invalidated, or does being an ImmutablePass mean that they always run? The previous patch used a ModulePass that created a cache, but was not actually queried unless run directly before some of the transformations, so how would you propose querying the cache once its created?


http://reviews.llvm.org/D10059

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