#16111: Inconsistent behavior of Data.Bits.shiftL with different optimization levels and -fllvm -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Without knowing anything about the implementation details of `shiftL`/`shiftR`, my hope would be that invoking them with a negative number of bits would throw an exception, regardless of the optimization level. I could certainly envision that an unsafe primop like `uncheckedShiftL#` would have undefined behavior if given a negative number of bits as an argument, but it feels like we should be able to do better for `shiftL`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16111#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler