[commit: ghc] master: Add comments on DmdAnal space leak fix (dd228b6)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/dd228b6eae18a05675b698fa309403d2310a269b/ghc

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commit dd228b6eae18a05675b698fa309403d2310a269b
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Apr 3 08:48:28 2017 +0100

    Add comments on DmdAnal space leak fix


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dd228b6eae18a05675b698fa309403d2310a269b
 compiler/stranal/DmdAnal.hs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/compiler/stranal/DmdAnal.hs b/compiler/stranal/DmdAnal.hs
index 2fc33a4..304a2be 100644
--- a/compiler/stranal/DmdAnal.hs
+++ b/compiler/stranal/DmdAnal.hs
@@ -90,6 +90,9 @@ evaluated everywhere that we produce it, so we just run a single
 seqBinds over the output before returning it, to ensure that there are
 no references holding on to the input Core program.
 
+This makes a ~30% reduction in peak memory usage when compiling
+DynFlags (cf Trac #9675 and #13426).
+
 This is particularly important when we are doing late demand analysis,
 since we don't do a seqBinds at any point thereafter. Hence code
 generation would hold on to an extra copy of the Core program, via