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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2019-11-08 17:49:35 +0000 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-04-02 01:45:58 -0400 |
| commit | b943b25d0786da64031ac63ddf9b4574182057bb (patch) | |
| tree | 529ac144237d1c4d7524360374fa8b33a6bd5ee4 /compiler/GHC/Iface/Tidy.hs | |
| parent | 3c09f636a459f50119bfbb5bf798b9a9e19eb464 (diff) | |
| download | haskell-b943b25d0786da64031ac63ddf9b4574182057bb.tar.gz | |
Re-engineer the binder-swap transformation
The binder-swap transformation is implemented by the occurrence
analyser -- see Note [Binder swap] in OccurAnal. However it had
a very nasty corner in it, for the case where the case scrutinee
was a GlobalId. This led to trouble and hacks, and ultimately
to #16296.
This patch re-engineers how the occurrence analyser implements
the binder-swap, by actually carrying out a substitution rather
than by adding a let-binding. It's all described in
Note [The binder-swap substitution].
I did a few other things along the way
* Fix a bug in StgCse, which could allow a loop breaker to be CSE'd
away. See Note [Care with loop breakers] in StgCse. I think it can
only show up if occurrence analyser sets up bad loop breakers, but
still.
* Better commenting in SimplUtils.prepareAlts
* A little refactoring in CoreUnfold; nothing significant
e.g. rename CoreUnfold.mkTopUnfolding to mkFinalUnfolding
* Renamed CoreSyn.isFragileUnfolding to hasCoreUnfolding
* Move mkRuleInfo to CoreFVs
We observed respectively 4.6% and 5.9% allocation decreases for the following
tests:
Metric Decrease:
T9961
haddock.base
Diffstat (limited to 'compiler/GHC/Iface/Tidy.hs')
| -rw-r--r-- | compiler/GHC/Iface/Tidy.hs | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/compiler/GHC/Iface/Tidy.hs b/compiler/GHC/Iface/Tidy.hs index 6459902a52..4bd11d227d 100644 --- a/compiler/GHC/Iface/Tidy.hs +++ b/compiler/GHC/Iface/Tidy.hs @@ -1239,8 +1239,7 @@ tidyTopIdInfo dflags rhs_tidy_env name orig_rhs tidy_rhs idinfo show_unfold | otherwise = minimal_unfold_info minimal_unfold_info = zapUnfolding unf_info - unf_from_rhs = mkTopUnfolding dflags is_bot tidy_rhs - is_bot = isBottomingSig final_sig + unf_from_rhs = mkFinalUnfolding dflags InlineRhs final_sig tidy_rhs -- NB: do *not* expose the worker if show_unfold is off, -- because that means this thing is a loop breaker or -- marked NOINLINE or something like that |