[commit: ghc] master: Comments only (9a4af2c)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/9a4af2c451baa685492ed576447c3ce2e335427d/ghc

>---------------------------------------------------------------

commit 9a4af2c451baa685492ed576447c3ce2e335427d
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Fri Dec 23 10:04:23 2016 +0000

    Comments only


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9a4af2c451baa685492ed576447c3ce2e335427d
 compiler/simplCore/SimplCore.hs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs
index ca869dc..8e9a9c6 100644
--- a/compiler/simplCore/SimplCore.hs
+++ b/compiler/simplCore/SimplCore.hs
@@ -344,6 +344,8 @@ getCoreToDo dflags
         -- Final run of the demand_analyser, ensures that one-shot thunks are
         -- really really one-shot thunks. Only needed if the demand analyser
         -- has run at all. See Note [Final Demand Analyser run] in DmdAnal
+        -- It is EXTREMELY IMPORTANT to run this pass, otherwise execution
+        -- can become /exponentially/ more expensive. See Trac #11731, #12996.
         runWhen (strictness || late_dmd_anal) CoreDoStrictness,
 
         maybe_rule_check (Phase 0)