[GHC] #13426: compile-time memory-usage regression for DynFlags between GHC 8.0 and GHC 8.2

[GHC]

#13426: compile-time memory-usage regression for DynFlags between GHC 8.0 and GHC
8.2
-------------------------------------+-------------------------------------
        Reporter:  hvr               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            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:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by rwbarton):

 I bisected and found out that the offending commit was none other than
 8d5cf8bf584fd4849917c29d82dcf46ee75dd035 "Join points". I didn't see this
 in my previous data because, ironically, `-dcore-lint` causes the large
 space usage to go away. So it seems likely to be a garden-variety thunk
 buildup in some field which is examined by core lint, but otherwise not
 examined until late in the compilation pipeline.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13426#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler