[LLVMdev] Valid debug information being deleted by DAGCombiner

Devang Patel dpatel at apple.com
Fri Apr 15 16:34:08 PDT 2011


On Apr 15, 2011, at 4:26 PM, Villmow, Micah wrote:

> Thanks Devang.
>  
> Is there any plan on making this implicit in the node creation? Or instead of using DebugLoc in SelectionDAG, use SDDbgValue's instead, or embedding the SDDbgValue in the debug loc itself somehow? This seems like something that shouldn't have to be handled on a case by case basis in the backends.
>  

DebugLoc and DbgValue serve different purposes. DebugLoc identifies source location and line number. It is part of llvm::Instruction, MachineInstr and SDNode. If these information is not generated by FE then it does not impact generated code. DebugLoc is more or less implicit in node creation. 

DbgValue refer to value (or node) for a variable. We do not want to represent them as a node in DAG, because debugging information should not impact generated code.

-
Devang

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