[llvm-dev] SD virt regs question

Lawrence, Peter via llvm-dev llvm-dev at lists.llvm.org
Tue Jun 28 12:40:15 PDT 2016


from the SD / SelectionDAG form of a global-virt-reg, IE a CopyToReg or CopyFromReg
where the Reg is a virtual-register (not a physical-register),
I need to compute the set of all other global-virt-regs that this one is connected
to through PHI nodes

as the PHI nodes set up equivalence relations,
I should be able to use ADT/EquivalenceClasses.h
which seems to implement a generic Union-Find algorithm,

I also note that there do not seem to be any uses of EquivalenceClasses
in CodeGen, so perhaps no one has had to do this before and I will
have to start from scratch ?


thanks,
--Peter Lawrence.
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