[LLVMdev] problem with runOnLoop

[Duncan Sands]

On 18/12/12 10:34, Alex wrote:
> John Criswell <criswell <at> illinois.edu> writes:
>
>>
>>
>>      On 12/12/11 9:59 AM, neda 8664 wrote:
>>
>>
>>        hi all,
>>        I want access to all basic blocks of function in a loop, so I used
>>        the following code:bool parallel::runOnLoop(Loop *L, LPPassManager
>>            &LPM)
>>            {
>>                for (Function::iterator bi= func->begin(); bi !=
>>            func->end(); bi++){
>>                   //
>>                 }
>>            }
>>
>>
>>      Are you modifying anything within this code (especially changes that
>>      add/remove basic blocks or change their Terminator instructions)?
>>      Depending on what you're doing, you may be invalidating the basic
>>      block iterator bi.
>>      -- John T.
>>
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>>
>
> Hello, I am getting same opt Stack dump error frequently as well. Also trying to
> access basic blocks in runOnBasicBlock(BasicBlock &BB). This is at the 4th line
> with errs():
> Instruction* current = BB.getTerminator();
> errs() << "\n last: "<<*current<<"\n";
> Instruction* prev = current->getPrevNode();
> errs()<<*prev<<"\n";
> What can be the cause?

This will happen if the terminator was the only instruction in the basic block.
Then prev will be pointing to rubbish.

Ciao, Duncan.