[commit: ghc] supercompiler: Add comments only (fac9686)

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : supercompiler

http://hackage.haskell.org/trac/ghc/changeset/fac968604ccd4e0595136c120fb2ad1ba5905af0

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

commit fac968604ccd4e0595136c120fb2ad1ba5905af0
Author: Max Bolingbroke <[email protected]>
Date:   Fri Oct 5 12:00:48 2012 +0100

    Add comments only

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

 .../supercompile/Supercompile/Drive/Process.hs     |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/compiler/supercompile/Supercompile/Drive/Process.hs b/compiler/supercompile/Supercompile/Drive/Process.hs
index cbbe6b6..0a73a22 100644
--- a/compiler/supercompile/Supercompile/Drive/Process.hs
+++ b/compiler/supercompile/Supercompile/Drive/Process.hs
@@ -638,6 +638,11 @@ type SpecRB = SpecHistory -> SpecM (SpecHistory, Deeds, Heap)
 type Depth = Train (SpecRB, Var) (SpecRB, Var)
 newtype SpecHistory = SH { unSH :: LinearHistory (State, Depth) }
 
+-- FIXME: AlreadySpeculated should be renamed when we generalise since heap bindings may change name
+
+-- NB: we can't use the domain of the heap incoming to the previous "reduce" call as the AlreadySpeculated
+-- set because normalisation may have caused some unspeculated bindings to enter the heap since the last "speculate"
+-- (e.g. consider splitting into the branch of a case where the branch has some top level lets)
 speculateHeap :: AlreadySpeculated -> (SCStats, Deeds, Heap) -> (AlreadySpeculated, (SCStats, Deeds, Heap))
 speculateHeap speculated (stats, deeds, heap@(Heap h _)) = {-# SCC "speculate" #-} (M.keysSet h', (mempty, deeds', heap'))
   where