[cfe-dev] Patch for fixing infinite rec. within PMTopLevelManager::schedulePass

[Chris Lattner]

On Feb 25, 2010, at 8:24 AM, philipp.legrum at daimler.com wrote:

> 
> Hello Developers,
> 
> I figured, that trying to load two passes that require each other results in an infinite recursion of PMTopLevelManager::schedulePass
> So I added tracing if schedulePass processes a pass that an outer invocation of schedulePass is already processing.
> If so, it aborts with an error message and outputs the cycle.
> 
> Would be nice if someone could review the patch and apply if suitable and/or give me feedback.

Hi Phillipp, this would probably be best if directed to the llvmdev mailing list, since it's about the LLVM passmanager,

-Chris

> 
> Thank you.
> Philipp
> 
> 
> 
> Index: include/llvm/PassManagers.h
> ===================================================================
> --- include/llvm/PassManagers.h        (revision 97141)
> +++ include/llvm/PassManagers.h        (working copy)
> @@ -256,6 +256,10 @@
>    SmallVector<ImmutablePass *, 8> ImmutablePasses;
>  
>    DenseMap<Pass *, AnalysisUsage *> AnUsageMap;
> +
> +  // Stack to keep track of circular module dependencies
> +  // during pass scheduling.
> +  SmallVector<const PassInfo *, 12> schedulingTrace;
>  };
>  
>  
> Index: lib/VMCore/PassManager.cpp
> ===================================================================
> --- lib/VMCore/PassManager.cpp        (revision 97141)
> +++ lib/VMCore/PassManager.cpp        (working copy)
> @@ -495,6 +495,26 @@
>    // TODO : Allocate function manager for this pass, other wise required set
>    // may be inserted into previous function manager
>  
> +  // Monitor circular dependencies of passes
> +  SmallVector<const PassInfo *, 12>::iterator result =
> +  std::find(schedulingTrace.begin(), schedulingTrace.end(),
> +            P->getPassInfo());
> +  
> +  // If we are about to schedule a pass we are already scheduling
> +  // we have detected a cyclic requirement.
> +  if (result != schedulingTrace.end()){
> +    errs() << "Error: Pass scheduler detected cyclic requirement in passes:\n";
> +    for (SmallVector<const PassInfo *, 12>::iterator I = result,
> +         E = schedulingTrace.end(); I != E; ++I){
> +      errs() << "  " << (*I)->getPassName() << "\n";
> +    }
> +    errs() << "  " << (*result)->getPassName() << "\n";
> +    exit(-1);
> +  }
> +  
> +  // Track the recursive pass scheduling
> +  schedulingTrace.push_back(P->getPassInfo());
> +
>    // Give pass a chance to prepare the stage.
>    P->preparePassManager(activeStack);
>  
> @@ -539,6 +559,7 @@
>        }
>      }
>    }
> +  schedulingTrace.pop_back();
>  
>    // Now all required passes are available.
>    addTopLevelPass(P);
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