[LLVMdev] Disable the Module Verifier pass?

[Zheng Wang]

Hello Nick,

Thanks a lot!

It seems -S is not a valid option for opt in LLVM-2.6.

Cheers,
Zheng

On 20 April 2010 14:57, Nick Lewycky <nicholas at mxc.ca> wrote:
> John Criswell wrote:
>>
>> Zheng Wang wrote:
>>>
>>> Hello,
>>>
>>> Is there anyway to disable the module verifier pass (in llvm-ld and llc)?
>>>
>>> I got an error as " Instruction does not dominate all uses!".
>>> Obviously, there must be something wrong. The module verifier simply
>>> aborts `llvm-ld` instead of generating bytecode. If somehow I can
>>> disable the module verifier, then I can use llc to produce LLVM
>>> assembly code for my program. This will help me to debug my pass.
>>>
>>
>> llc assumes that its input passes verification, so disabling the
>> verifier pass in the linker is probably not going to be as helpful as
>> you think.
>>
>> You can, however, disable the verifier in opt.  So, you can do the
>> following:
>>
>> 1) Run opt -std-link-opts -load<your pass.so>  -<your pass name>
>> -disable-verify<input.bc>  -f -o<output.bc>
>>
>> The -std-link-opts option runs the optimization passes used by llvm-ld.
>> You can now disassemble output.bc to see what your pass is doing wrong.
>>
>> If, for some reason, the bitcode writer cannot write your invalid
>> bitcode to disk, then you will have to run the above command in the
>> debugger.
>
> Not necessarily. The -S option on opt will cause opt to run M->dump() for
> the whole module. This is great because unlike the bitcode writer, the
> module dumper is built to be resilient in the face of invalid IR. "opt [...]
> -disable-verify -S" is the way to debug a bad pass.
>
> And indeed, trying to run the result through llc will simply not work. The
> parser will reject it as invalid.
>
> Nick
>
>  Remove the -disable-verify option so that opt crashes in the
>>
>> verifier.  Then use the debugger to examine what is wrong.  Remember
>> that many LLVM classes (such as Module, Value, Instruction, BasicBlock,
>> and Function) have a dump() method that will print their contents to the
>> screen.  So, if using gdb, the verifier crashes because instruction I
>> doesn't dominate all of its uses, then you can use:
>>
>> % call I->dump()
>>
>> ... to see what the instruction pointed to by I looks like.
>>
>> -- John T.
>>
>>> Cheers
>>> Zheng
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>>
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>
>



-- 
Best regards,

WANG Zheng