[LLVMdev] alias analysis in backend

[Jonas Paulsson]

Hi,

I would like to implement alias analysis in my backend. I would like to for example get the result that two stack-accesses with different offsets (indexes), would return noAlias. However, I'm somewhat confused as there is no notion of offset for the Location object.

I would also like to call ScheduleDAGInstr::buildSchedGraph() with this AliasAnalysis and have MIsNeedsChainEdge() return false in this case.

What should I do? Adding a MemoryOperand to such an instruction seems right, but it doesn't seem to fit quite. What Value would be referenced? BasicAliasAnalysis returns MustAlias for the same Value, e g 'Stack'.

Should I implement a target AliasAnalysis, perhaps derived from BasicAliasAnalysis, and make it required for my pass that will be using it?

If not, could I make this work with BasicAliasAnalysis by adding the right memory operands?

Thanks,

Jonas Paulsson



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