llvm dev - Jul 2007 - [LLVMdev] Writing a pass for the opt tool: likely documentation bug

Hi,

I'm currently attempting to implement a pass that will hopefully run 
under the opt tool. Currently, I'm having some difficulties -- the 
sample code for the Hello pass (see 
http://llvm.org/docs/WritingAnLLVMPass.html) doesn't work. The first 
error is that the section starting 'As a while, the cpp file looks 
like:' omits the declaration for char Hello::ID = 0 that is given 
separately above. If you add this, opt still fails with the message:

opt: /usr/local/rse/llvm/src/lib/VMCore/Pass.cpp:158: void
<unnamed>::PassRegistrar::RegisterPass(llvm::PassInfo&): Assertion
`Inserted && "Pass registered multiple times!"' failed.

which appears to be triggered by the RegisterPass<Hello> X... line in the
source (the error disappears if you comment that line out, though for obvious
reasons the pass won't work if you do that). I've checked, there
definitely isn't anything weird going on that would cause more than one
instance of RegisterPass<Hello> to be seen by the compiler.

I am intending to have a go at writing probably several passes that will attempt
a SPIN-like code to code transformation that turns llvm bitcode into another
piece of llvm bitcode that, when run, has the effect of model-checking the
original program. I won't get much done if I can't make any of my passes
work, of course, so any tips would be gratefully appreciated at this point!

(I'm using the LLVM 2.0 release version).

Thank you in advance,
Sarah

Sarah,

We have Hello pass in svn at

	lib/Transforms/Hello

This is a working example. I will update documentation to include  
"char Hello::ID = 0".

On Jul 25, 2007, at 1:51 PM, Sarah Thompson wrote:
> Hi,
>
> I'm currently attempting to implement a pass that will hopefully run
> under the opt tool. Currently, I'm having some difficulties -- the
> sample code for the Hello pass (see
> http://llvm.org/docs/WritingAnLLVMPass.html) doesn't work. The first
> error is that the section starting 'As a while, the cpp file looks
> like:' omits the declaration for char Hello::ID = 0 that is given
> separately above. If you add this, opt still fails with the message:
>
> opt: /usr/local/rse/llvm/src/lib/VMCore/Pass.cpp:158: void  
> <unnamed>::PassRegistrar::RegisterPass(llvm::PassInfo&):
Assertion
> `Inserted && "Pass registered multiple times!"'
failed.
>
> which appears to be triggered by the RegisterPass<Hello> X... line  
> in the source (the error disappears if you comment that line out,  
> though for obvious reasons the pass won't work if you do that).
I've
> checked, there definitely isn't anything weird going on that would  
> cause more than one instance of RegisterPass<Hello> to be seen by  
> the compiler.
This may happen if either you're sharing ::ID for two passes or you're  
registering Hello twice.

-
Devang
>
>
> I am intending to have a go at writing probably several passes that  
> will attempt a SPIN-like code to code transformation that turns llvm  
> bitcode into another piece of llvm bitcode that, when run, has the  
> effect of model-checking the original program. I won't get much done  
> if I can't make any of my passes work, of course, so any tips would  
> be gratefully appreciated at this point!
>
> (I'm using the LLVM 2.0 release version).
>
> Thank you in advance,
> Sarah
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

It can also happen if you link *anything* from LLVM into the Hello.so.
Don't do that :)

Reid.

On Wed, 2007-07-25 at 14:02 -0700, Devang Patel wrote:
> Sarah,
> 
> We have Hello pass in svn at
> 
> 	lib/Transforms/Hello
> 
> This is a working example. I will update documentation to include  
> "char Hello::ID = 0".
> 
> On Jul 25, 2007, at 1:51 PM, Sarah Thompson wrote:
> 
> > Hi,
> >
> > I'm currently attempting to implement a pass that will hopefully
run
> > under the opt tool. Currently, I'm having some difficulties -- the
> > sample code for the Hello pass (see
> > http://llvm.org/docs/WritingAnLLVMPass.html) doesn't work. The
first
> > error is that the section starting 'As a while, the cpp file looks
> > like:' omits the declaration for char Hello::ID = 0 that is given
> > separately above. If you add this, opt still fails with the message:
> >
> > opt: /usr/local/rse/llvm/src/lib/VMCore/Pass.cpp:158: void  
> > <unnamed>::PassRegistrar::RegisterPass(llvm::PassInfo&):
Assertion
> > `Inserted && "Pass registered multiple times!"'
failed.
> >
> > which appears to be triggered by the RegisterPass<Hello> X...
line
> > in the source (the error disappears if you comment that line out,  
> > though for obvious reasons the pass won't work if you do that).
I've
> > checked, there definitely isn't anything weird going on that would
> > cause more than one instance of RegisterPass<Hello> to be seen
by
> > the compiler.
> 
> This may happen if either you're sharing ::ID for two passes or
you're
> registering Hello twice.
> 
> -
> Devang
> 
> >
> >
> > I am intending to have a go at writing probably several passes that  
> > will attempt a SPIN-like code to code transformation that turns llvm  
> > bitcode into another piece of llvm bitcode that, when run, has the  
> > effect of model-checking the original program. I won't get much
done
> > if I can't make any of my passes work, of course, so any tips
would
> > be gratefully appreciated at this point!
> >
> > (I'm using the LLVM 2.0 release version).
> >
> > Thank you in advance,
> > Sarah
> >
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev