I think you want to turn on restrict-it here: def HasV8Ops : SubtargetFeature<"v8", "HasV8Ops", "true", "Support ARM v8 instructions", [HasV7Ops, FeatureVirtualization, FeatureMP]>; by default yes? -eric http://reviews.llvm.org/D10416 EMAIL PREFERENCES http://reviews.llvm.org/settings/panel/emailpreferences/