Well, perhaps I was not quite correct.
I mostly had in mind things like (for example) `clang` on Windows doesn't supporting `-flto`, but using separate utilities, e.g doing `llvm-
#10074: Implement the 'Improved LLVM Backend' proposal -------------------------------------+------------------------------------- Reporter: thoughtpolice | Owner: angerman Type: task | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler (LLVM) | Version: Resolution: | Keywords: llvm, codegen Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #11295, #12470 | Differential Rev(s): Phab:D530 Wiki Page: | wiki:ImprovedLLVMBackend | -------------------------------------+------------------------------------- Comment (by angerman): Replying to [comment:18 awson]: link` between `opt` and `llc` we can accomplish the thing.
OTOH, we still can call `clang` twice, first instead of `opt` then
instead of `llc` with `llvm-link` in-between.
Still I'm very much not sure we need to bother with the beast like
`clang` to only be able to get rid of literally a couple of lines of haskell code. Moreover, I'm not sure OS X -O3 example is quite relevant here. Do you mean using `-O3` with `opt` and/or `llc` driver yields different results from if we use the same `-O3` with `clang` driver on the same version of llvm/clang? The actual diff is here: https://phabricator.haskell.org/D3352, which you might or might now have seen. Maybe the `-flto` on windows has changed with llvm4 already? We could I guess, do two clang runs, my intention though is to replace `ghc -> llvm ir -> opt -> llc -> mangler -> as -> object` to `ghc -> llvm ir -> clang -> object`. The mentioned macOS `-O3` bug, referred to the following lines, which sadly do not say which llvm version exhibited the issue. {{{ -- Bug in LLVM at O3 on OSX. llvmOpts = if platformOS (targetPlatform dflags) == OSDarwin then ["-O1", "-O2", "-O2"] else ["-O1", "-O2", "-O3"] }}} I'm proposing to take this opportunity and start from a blank slate and drop any **maybe it's still broken, maybe not** parts from the pipeline. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10074#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler