Push heap checks into case alternatives if possible for comparisons.

compiler/codeGen/StgCmmExpr.hs

@@ -502,7 +502,7 @@ cgCase scrut bndr alt_type alts
        ; let ret_bndrs = chooseReturnBndrs bndr alt_type alts
              alt_regs  = map (idToReg dflags) ret_bndrs
        ; simple_scrut <- isSimpleScrut scrut alt_type
-       ; let do_gc  | is_cmp_op scrut  = False  -- See Note [GC for conditionals]
+       ; let do_gc  -- | is_cmp_op scrut  = False  -- See Note [GC for conditionals]
                     | not simple_scrut = True
                     | isSingleton alts = False
                     | up_hp_usg > 0    = False