[llvm-commits] [llvm] r130551 - in /llvm/trunk: include/llvm/Transforms/Utils/BasicBlockUtils.h lib/Transforms/Utils/BasicBlockUtils.cpp lib/Transforms/Utils/SSAUpdater.cpp

[Evan Cheng]

Hi Devang,

I share Duncan's concern. This may impact compile time. Is the scanning the only solution?

Evan

On Apr 30, 2011, at 5:23 AM, Duncan Sands wrote:

> Hi Devang,
> 
>> +/// GetFirstDebugLocInBasicBlock - Return first valid DebugLoc entry in a
>> +/// given basic block.
>> +DebugLoc llvm::GetFirstDebugLocInBasicBlock(const BasicBlock *BB) {
>> +  for (BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
>> +       BI != BE; ++BI) {
>> +    DebugLoc DL = BI->getDebugLoc();
>> +    if (!DL.isUnknown())
>> +      return DL;
>> +  }
>> +  return DebugLoc();
>> +}
> 
> this potentially scans through the entire basic block which might be expensive
> if it is big.  Also, it's not clear to me that this makes any sense.  Suppose
> the first instructions in the basic block have no line number info.  Why should
> the phi node get the same line number as some random instruction deep down in
> the basic block?  How about just giving the phi node the same line info as the
> first instruction in the basic block?  If it doesn't have any then too bad.
> 
> Ciao, Duncan.
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