checkCond :: CmmExpr -> CmmLint ()
checkCond (CmmMachOp mop _) | isComparisonMachOp mop = return ()
+checkCond (CmmLit (CmmInt x t)) | x == 0 || x == 1, t == wordWidth = return () -- constant values
checkCond expr = cmmLintErr (hang (text "expression is not a conditional:") 2
(ppr expr))