[PATCH v2 1/1] utils: Fix segfault in flattencfg

[Tom Stellard]

On 08/09/2014 03:52 PM, Jan Vesely wrote:
> On Fri, 2014-08-08 at 14:18 -0700, Matt Arsenault wrote:
>> On Aug 8, 2014, at 1:41 PM, Jan Vesely <jan.vesely at rutgers.edu> wrote:
>>
>>> v2: continue iterating through the rest of the bb
>>>     use for loop
>>>
>>> Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
>>> ---
>>> lib/Transforms/Utils/FlattenCFG.cpp | 9 +++++----
>>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/lib/Transforms/Utils/FlattenCFG.cpp b/lib/Transforms/Utils/FlattenCFG.cpp
>>> index 51ead40..4eb3e3d 100644
>>> --- a/lib/Transforms/Utils/FlattenCFG.cpp
>>> +++ b/lib/Transforms/Utils/FlattenCFG.cpp
>>> @@ -238,9 +238,13 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
>>>      // Do branch inversion.
>>>      BasicBlock *CurrBlock = LastCondBlock;
>>>      bool EverChanged = false;
>>> -    while (1) {
>>> +    for (;CurrBlock != FirstCondBlock;
>>> +          CurrBlock = CurrBlock->getSinglePredecessor()) {
>>>        BranchInst *BI = dyn_cast<BranchInst>(CurrBlock->getTerminator());
>>>        CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition());
>>> +      if (!CI)
>>> +        continue;
>>> +
>>>        CmpInst::Predicate Predicate = CI->getPredicate();
>>>        // Canonicalize icmp_ne -> icmp_eq, fcmp_one -> fcmp_oeq
>>>        if ((Predicate == CmpInst::ICMP_NE) || (Predicate == CmpInst::FCMP_ONE)) {
>>> @@ -248,9 +252,6 @@ bool FlattenCFGOpt::FlattenParallelAndOr(BasicBlock *BB, IRBuilder<> &Builder,
>>>          BI->swapSuccessors();
>>>          EverChanged = true;
>>>        }
>>> -      if (CurrBlock == FirstCondBlock)
>>> -        break;
>>> -      CurrBlock = CurrBlock->getSinglePredecessor();
>>>      }
>>>      return EverChanged;
>>>    }
>>
>> Needs tests
>
> sorry, I misunderstood what you meant by test the first time.
>
> I wanted to add a flattencfg pass specific test but ran into problems
>
> is there an easy way to run only the flattencfg pass?
> opt -pass_name works only for analytical passes,
> and llc ... -stop-after=flattencfg reports pass not registered.
>

You should be able to run any pass using opt.  Did you look at the 
output of opt -help-hidden ?

Actually, flattencfg doens't show up for me in the help options.
This may be because it doesn't get initialized with the other passes in
lib/Transforms/Scalar/Scalar.cpp.  Try adding the initialize call there 
and see if that makes it work with opt.

-Tom


> I guess I'll have to add a codegen test.
>
> I also found the parallel{or,and}ifcollapse tests, that are marked XFAIL
> for unrelated reason. Should I try to fix those or add a new test?
>
> jan
>