llvm dev - Apr 2008 - [LLVMdev] Disabling Verifier

Hi,

I've noticed that the funcionality in the Verifier.cpp significantely 
slows down the compilation, especially for big basic blocks. In this 
case  the llvm::DominatorTree::dominates() seems to consume a lot of time.

Some debugging has shown that it is the Assert2() macro usage in the
Verifier::visitInstruction(), arount this place:
  // Definition must dominate use unless use is unreachable!
  Assert2(DT->dominates(Op, &I) ||
         !DT->dominates(&BB->getParent()->getEntryBlock(), BB),
         "Instruction does not dominate all uses!", Op, &I);


  Question: Is it possible to switch off/disable this checks? I'm 
exprimenting with speeding up the instruction scheduling and instruction 
selection and these checks in Verifer.cpp introduce too much of 
interference with results of my optimizations, so that it becomes 
difficult to decide what are the most time-consuming parts of the compiler.

Thanks,
  -Roman






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On Apr 18, 2008, at 6:55 AM, Roman Levenstein wrote:
> Hi,
>
> I've noticed that the funcionality in the Verifier.cpp significantely
> slows down the compilation, especially for big basic blocks. In this
> case  the llvm::DominatorTree::dominates() seems to consume a lot of  
> time.
>
> Some debugging has shown that it is the Assert2() macro usage in the
> Verifier::visitInstruction(), arount this place:
>  // Definition must dominate use unless use is unreachable!
>  Assert2(DT->dominates(Op, &I) ||
>         !DT->dominates(&BB->getParent()->getEntryBlock(), BB),
>         "Instruction does not dominate all uses!", Op, &I);
>
>
>  Question: Is it possible to switch off/disable this checks? I'm
> exprimenting with speeding up the instruction scheduling and  
> instruction
> selection and these checks in Verifer.cpp introduce too much of
> interference with results of my optimizations, so that it becomes
> difficult to decide what are the most time-consuming parts of the  
> compiler.
You can just stop running the verifier with '-disable-verifier' to  
opt, for example.  However, it would be better to make this check more  
scalable :)  Please file a "verifier is slow" bugzilla with a bc file,
thanks!

-Chris