#14208: Performance with O0 is much better than the default or with -O2, runghc performs the best -------------------------------------+------------------------------------- Reporter: harendra | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by harendra): Alright, I guessed that ignoring the interface disables inlining so the problem has something to do with inlining. I looked at all the inlining options available and narrowed down the problem to `-fno-pre-inlining`. Just using `-fno-pre-inlining` brings us back to the performance that we are seeing with -O0. The fine manual does not say what pre-inlining is so I have to look at the GHC code again. I am confused by the fine manual. It says: {{{ -fno-pre-inlining Default: off }}} Does that mean pre-inlining is on by default? Can we make this clearer, explicit? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14208#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler