[llvm-commits] [llvm] r50382 - in /llvm/trunk: include/llvm/LinkAllPasses.h include/llvm/Transforms/Scalar.h lib/Transforms/Scalar/DeadLoopElimination.cpp

[Owen Anderson]

On Apr 29, 2008, at 1:36 PM, Chris Lattner wrote:
>> +  for (Loop::block_iterator LI = L->block_begin(), LE = L-
>>> block_end();
>> +       LI != LE; ++LI) {
>> +    for (BasicBlock::iterator BI = (*LI)->begin(), BE = (*LI)- 
>> >end();
>> +         BI != BE; ) {
>> +      Instruction* I = BI++;
>> +      I->eraseFromParent();
>> +    }
>> +
>> +    (*LI)->eraseFromParent();
>> +  }
>
> You are incrementing LI after you erase *LI.

I'm actually reasonably confident that this is safe.  I'm iterating  
over the loop's block list, not over the function ilist.  Erasing *LI  
doesn't remove LI from the loop's block list, it just makes it a  
pointer to freed memory.  You'll note that the next step is to remove  
the blocks from LoopInfo, which does remove them from the loop's block  
list, and from the block lists of any parent loops as well.

--Owen

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