[LLVMdev] Error when trying to chain two llvm transform passes

[Krzysztof Parzyszek]

On 10/30/2012 5:35 PM, Ashwin kumar wrote:
>
>
> No. I am not sure how they work . I am trying to use the INITIALIZE_PASS
> macro. I get the following error
>
>
> *error: definition or redeclaration of 'initializeMyPassNamePass' not in
> a namespace enclosing 'llvm' *
> *
> *
>
>
> should i add the passname to a header file ? if so where?

The easiest way is to "cheat" and see how existing code does it. :)

Take, dead store elimination, for example:

In DeadStoreElimination.cpp, there is

     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesCFG();
       AU.addRequired<DominatorTree>();
       AU.addRequired<AliasAnalysis>();
       AU.addRequired<MemoryDependenceAnalysis>();
       AU.addPreserved<AliasAnalysis>();
       AU.addPreserved<DominatorTree>();
       AU.addPreserved<MemoryDependenceAnalysis>();
     }

and

INITIALIZE_PASS_BEGIN(DSE, "dse", "Dead Store Elimination", false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTree)
INITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(DSE, "dse", "Dead Store Elimination", false, false)


The macros will generate a function called "initializeDSEPass".

Now, in the same file, in the constructor, there is a call to it:
     DSE() : FunctionPass(ID), AA(0), MD(0), DT(0) {
       initializeDSEPass(*PassRegistry::getPassRegistry());
     }


Now you can grep the sources to see if the "initializeDSEPass" is in any 
header.  In my source tree, it's in:

include/llvm/InitializePasses.h
lib/Transforms/Scalar/DeadStoreElimination.cpp
lib/Transforms/Scalar/Scalar.cpp

In InitializePasses.h there is a namespace "llvm" with all the 
initialization functions listed in it.  For a particular pass, the other 
occurrences may differ slightly, but this is the core of what you need.

You don't really need to use RegisterPass.  I only found two places that 
use it and they both are in the code generation.

-Krzysztof


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