[GHC] #7198: New codegen more than doubles compile time of T3294

[GHC]

#7198: New codegen more than doubles compile time of T3294
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        Reporter:  simonmar          |                Owner:  simonmar
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.4.2
  (CodeGen)                          |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #4258             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonmar):

 I suspect that R1 is not stable enough, but I'm not sure.  You could
 probably find a smaller test case that fails by running the testsuite with
 stage=1.

 In any case, this probably isn't a good idea, at least in general, because
 if a free var is used more than once then we'll get a memory accesses to
 reference it each time, rather than loading it into a register.  Of course
 if we run out of registers then it might be a good idea... but that's hard
 to tell at this stage (better to let the register allocator make that
 decision).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7198#comment:12>
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