[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 George):

 One interesting option clang would give us is to specify -Os, which
 according to the clang man page is like the clang -O2 option but with
 extra optimizations to reduce code size. opt and llc don't seem to have
 that option. Of  course this wouldn't help the ghc code gen but might help
 with clang  as the -O3 option along with -Os would  allow users to
 experiment with size/speeed tradeoffs.

 I have seen discussions about not doing certain optimizations as the code
 size would be increased and we were unsure if the result would be faster
 or not.

 OTOH  I don't know very much and maybe all the important code size / speed
 tradeoffs are made before we get to llvm.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10074#comment:22>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler