[PATCH] D65354: [X86] Let MachineCombiner reassociate adds for ILP

[Florian Hahn via Phabricator via llvm-commits]

fhahn added subscribers: Gerolf, MatzeB, stoklund, fhahn.
fhahn added a comment.

There's RegPressureTracker (https://llvm.org/docs/doxygen/classllvm_1_1RegPressureTracker.html) which can be used to track register pressure through a region of MBBs. The MachineCombiner use MachineTraceMetrics to guide which combines to apply and MTM does so by choosing a preferred trace.  I think we could track pressure through that trace and compare the pressure difference of  the removed/added instructions per combine. At least from a high-level perspective, adding register pressure info to MTM makes sense to me.

Gerolf, do you think that would be good extension to MachineCombiner?


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