llvm dev - Feb 2009 - [LLVMdev] AnalysisUsage & Call Graph SCC Pass Manager

Hello,

I have the following sequence of passes (using --debug-pass=Structure):

...
  ModulePass Manager
    FunctionPass Manager
      Preliminary module verification
      Dominator Tree Construction
      Module Verifier
    MyModulePass0
    MyAnalysis
    Basic CallGraph Construction
    MyModulePass1
    MyAnalysis
    MyModulePass2
    Basic CallGraph Construction
    Call Graph SCC Pass Manager
      MyCallGraphSCCPass
    MyModulePass3
    ...

I have the following analysis usages:

MyModulePass0 does not require anything and does not preserve anything.
MyModulePass1 requires MyAnalysis & Callgraph but does not preserve them.
MyModulePass2 requires MyAnalysis and preserves it.
MyCallGraphSCCPass requires MyAnalysis but does not preserve it.
MyModulePass3 requires MyAnalysis and preserves it.

I am expecting MyAnalysis to be re-scheduled between MyCallGraphSCCPass and
MyModulePass3 but it's not happening.

If I set MyModulePass3 to not preserve MyAnalysis, then I see MyAnalysis
re-scheduled after MyModulePass3.

It seems like the fact that MyAnalysis is not preserved by MyCallGraphSCCPass
is somehow not propagated outside the Call Graph SCC Pass Manager.

Is there something wrong with that sequence ?

Thanks,
Julien

-- 
Julien Lerouge
PGP Key Id: 0xB1964A62
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On Feb 26, 2009, at 6:01 PM, Julien Lerouge wrote:
> Hello,
>
> I have the following sequence of passes (using --debug- 
> pass=Structure):
>
> ...
>  ModulePass Manager
>    FunctionPass Manager
>      Preliminary module verification
>      Dominator Tree Construction
>      Module Verifier
>    MyModulePass0
>    MyAnalysis
>    Basic CallGraph Construction
>    MyModulePass1
>    MyAnalysis
>    MyModulePass2
>    Basic CallGraph Construction
>    Call Graph SCC Pass Manager
>      MyCallGraphSCCPass
>    MyModulePass3
>    ...
>
> I have the following analysis usages:
>
> MyModulePass0 does not require anything and does not preserve  
> anything.
> MyModulePass1 requires MyAnalysis & Callgraph but does not preserve  
> them.
> MyModulePass2 requires MyAnalysis and preserves it.
> MyCallGraphSCCPass requires MyAnalysis but does not preserve it.
> MyModulePass3 requires MyAnalysis and preserves it.
>
> I am expecting MyAnalysis to be re-scheduled between  
> MyCallGraphSCCPass and
> MyModulePass3 but it's not happening.
>
> If I set MyModulePass3 to not preserve MyAnalysis, then I see  
> MyAnalysis
> re-scheduled after MyModulePass3.
>
> It seems like the fact that MyAnalysis is not preserved by  
> MyCallGraphSCCPass
> is somehow not propagated outside the Call Graph SCC Pass Manager.
>
> Is there something wrong with that sequence ?
It is a bug. CGPassManager is  incorrectly claiming that it is  
preserving all analysis info.
-
Devang
>
>
> Thanks,
> Julien
>
> -- 
> Julien Lerouge
> PGP Key Id: 0xB1964A62
> PGP Fingerprint: 392D 4BAD DB8B CE7F 4E5F FA3C 62DB 4AA7 B196 4A62
> PGP Public Key from: keyserver.pgp.com
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
-
Devang

On Tue, Mar 03, 2009 at 11:13:22AM -0800, Devang Patel
wrote:
> It is a bug. CGPassManager is  incorrectly claiming that it is  
> preserving all analysis info.
> -
> Devang
Thanks, I filed http://llvm.org/bugs/show_bug.cgi?id=3703 with a simple
test case.

Julien

-- 
Julien Lerouge
PGP Key Id: 0xB1964A62
PGP Fingerprint: 392D 4BAD DB8B CE7F 4E5F FA3C 62DB 4AA7 B196 4A62
PGP Public Key from: keyserver.pgp.com