[GHC] #10074: Implement the 'Improved LLVM Backend' proposal

[GHC]

#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 awson):

 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-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?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10074#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler