[LLVMdev] Win32 JIT issue + bug in ScheduleDAGSNodes.h?

[srs]

Bill Wendling wrote:
> On Dec 31, 2008, at 5:57 AM, srs wrote
>> Bill Wendling wrote:
>>     
>>> On Dec 30, 2008, at 4:51 PM, srs wrote:
>>>
>>>
>>>       
>>>> 2. There seems to be an issue in ScheduleDAGSDNodes.h when in debug
>>>> mode. The problem is the evaluation of "&SUnits[0];" which  
>>>> ASSERT's in
>>>> VC++'s vector[] implementation (when _HAS_ITERATOR_DEBUGGING is on).
>>>>
>>>> As a work-around, I commented out the debug code (see "patch"  
>>>> below.)
>>>>
>>>> What would the proper solution be? The idiom appears to be allowed  
>>>> by
>>>> the C++03 standard, but at least VC++ 2008 Express Edition with
>>>> _HAS_ITERATOR_DEBUGGING fails.
>>>>         
>>> What is the assertion message?
>>>       
>> "vector subscript out of range"
>>
>> This is the asserting code from <vector> :
>>
>>
>>    const_reference operator[](size_type _Pos) const
>>        {    // subscript nonmutable sequence
>>
>> #if _HAS_ITERATOR_DEBUGGING
>>        if (size() <= _Pos)
>>            {
>>            _DEBUG_ERROR("vector subscript out of range");
>>            _SCL_SECURE_OUT_OF_RANGE;
>>            }
>> #endif /* _HAS_ITERATOR_DEBUGGING */
>>        _SCL_SECURE_VALIDATE_RANGE(_Pos < size());
>>
>>        return (*(_Myfirst + _Pos));
>>        }
>>
>>
>>     
> Okay. I wonder if we can modify it to check that the vector has  
> elements in it. Could you try this patch and let me know if it works  
> for you?
>
> -bw
>
> Index: include/llvm/CodeGen/ScheduleDAGSDNodes.h
> ===================================================================
> --- include/llvm/CodeGen/ScheduleDAGSDNodes.h	(revision 61532)
> +++ include/llvm/CodeGen/ScheduleDAGSDNodes.h	(working copy)
> @@ -103,10 +103,13 @@
>       ///
>       SUnit *NewSUnit(SDNode *N) {
>   #ifndef NDEBUG
> -      const SUnit *Addr = &SUnits[0];
> +      const SUnit *Addr = 0;
> +      if (SUnits.size() > 0)
> +        Addr = &SUnits[0];
>   #endif
>         SUnits.push_back(SUnit(N, (unsigned)SUnits.size()));
> -      assert(Addr == &SUnits[0] && "SUnits std::vector reallocated on  
> the fly!");
> +      assert((Addr == 0 || Addr == &SUnits[0]) &&
> +             "SUnits std::vector reallocated on the fly!");
>         SUnits.back().OrigNode = &SUnits.back();
>         return &SUnits.back();
>       }
>   

This works fine for me.

/Stein Roger