[LLVMdev] alias information on machine instructions

Dan Gohman djg at cray.com
Wed May 23 07:54:29 PDT 2007

On Wed, May 23, 2007 at 12:23:38AM -0700, Chris Lattner wrote:
> On Fri, 4 May 2007, Florian Brandner wrote:
> > i had a look at the SelectionDAG based schedulers. it seems that
> > aliasing loads/stores are chained together by the DAGCombiner. after
> > scheduling, when the MachineInstrs are created, the alias information
> > cannot be used anymore in the current framework. is this correct?
> Right.  The original Value*'s are preserved in the DAG, but dropped when 
> MachineInstrs are created.  We could add a machineoperand to capture this 
> Value* if desired.

Another benefit of keeping the original Value*'s (and offsets) around is it
would provide more information that could be used for verbose asm output
and MachineInstr-level dumps, which would be quite nice.


Dan Gohman, Cray Inc.

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