[GHC] #12745: Compile cmm file for register allocator stats

[GHC]

#12745: Compile cmm file for register allocator stats
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        Reporter:  tjakway           |                Owner:  tjakway
            Type:  task              |               Status:  new
        Priority:  lowest            |            Milestone:
       Component:  Compiler (NCG)    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12744            |  Differential Rev(s):  Phab:D2621
       Wiki Page:                    |
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Comment (by tjakway):

 The issue stems from RegAlloc.Graph.Main lines 100-106:

 {{{
 -- If any of these dump flags are turned on we want to hang on to
 -- intermediate structures in the allocator - otherwise tell the
 -- allocator to ditch them early so we don't end up creating space leaks.
 let dump = or
     [ dopt Opt_D_dump_asm_regalloc_stages dflags
     , dopt Opt_D_dump_asm_stats dflags
     , dopt Opt_D_dump_asm_conflicts dflags ]

 }}}

 Without the dump flags the intermediate structures we need are scrapped.
 I propose adding a flag to keep the intermediates without printing them.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12745#comment:2>
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