[llvm-dev] How a module pass can use analysis information?

[Michael Kruse via llvm-dev]

Using the legacy pass manager, it is generally not possible to use
lower-level passes (The only exception is that module passes can use
function passes using `getOnTheFlyPass`).

You can still create your own pass manager hierachy. An example is here:
http://llvm.org/viewvc/llvm-project/polly/trunk/lib/CodeGen/CodegenCleanup.cpp?revision=274595&view=markup

You need to create a whole stack of pass managers. Unfortunately I
don't know how to reuse the dependent analyses from the 'main' pass
manager stack (eg. TargetLibraryInfoWrapperPass)

Michael


2016-09-19 19:53 GMT+02:00 Minghwa Wang via llvm-dev <llvm-dev at lists.llvm.org>:
> I am trying to write a llvm module pass by overriding the runOnModule(Module
> &M), but my pass needs the RegioinInfo analysis to find regions to get my
> pass working.
>
> I tried to do the following in my module pass:
>     RegionInfoPass RIP;
>     if (RIP.runOnFunction(*F1)) {
>       assert(false && "Failed to run runOnFunction");
>     }
>     RegionInfo *RI = &RIP.getAnalysis<RegionInfoPass>().getRegionInfo();
>     RI->dump();
> It compiles without problem, but when I run it, I got the following errors:
>     AnalysisType&llvm::Pass::getAnalysis() const [with AnalysisType =
> llvm::RegionInfoPass]:
>     Assertion `Resolver && "Pass has not been inserted into a PassManager
> object!"' failed.
>
> I also tried to use RGPassManager as below:
>     RGPassManager RGPM;
>     if (RGPM.runOnFunction(*F1)) {
>       assert(false && "Failed to run runOnFunction");
>     }
> Again, it compiles without problem, but when I run it, I got the same errors
> as above.
>
> Is anyone can show me what is the correct way for a module pass to use
> RegionInfo analysis?
>
> Thanks,
> Ming-Hwa
>
>
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