[GHC] #10137: Rewrite switch code generation

[GHC]

#10137: Rewrite switch code generation
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        Reporter:  nomeata           |                   Owner:
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.9
  (CodeGen)                          |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:  #9157, #8326,     |  Differential Revisions:
  #8317                              |
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Changes (by jstolarek):

 * related:   => #9157, #8326, #8317


Comment:

 > The Common Block Optimization on Cmm happens later in the pipeline,
 making it non-trivial to detect branches that do the same thing.
 #9157 demonstrates a case where CBE fails, although it definitely
 shouldn't.

 Re #8326 I spent several weeks trying to fix it but ultimately I failed.
 You can find various experimental versions of my code on these branches:
 [[https://github.com/jstolarek/ghc/tree/T8326-heap-checks|T8326-heap-
 checks]]
 [[https://github.com/jstolarek/ghc/tree/T8326-heap-checks-aletr-
 gc_plan|T8326-heap-checks-aletr-gc_plan]]
 [[https://github.com/jstolarek/ghc/tree/T8326-heap-checks-alternative-
 plan|T8326-heap-checks-alternative-plan]]
 [[https://github.com/jstolarek/ghc/tree/T8326-heap-checks-precompile-
 alts|T8326-heap-checks-precompile-alts]]
 though it probably will be easier to write your own code.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10137#comment:2>
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