[GHC] #13535: vector test suite uses excessive memory on GHC 8.2

[GHC]

#13535: vector test suite uses excessive memory on GHC 8.2
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #10800            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 OK, but all those call sites must be applied to the same combining-
 function argument (else the loop would be different in each case).  So we
 just have lots of all to `foldlM k z`, for a particular `k` and `z`?

 Could we CSE those calls before inlining the `foldlM`?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13535#comment:18>
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