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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2019-11-08 17:49:35 +0000 |
|---|---|---|
| committer | Alp Mestanogullari <alp@well-typed.com> | 2020-04-01 03:20:38 -0400 |
| commit | 812c475056e4e16b93ba1fa79d8b44b1329759b1 (patch) | |
| tree | 0ecae73b7a38d6068a18214b73fd94bae16db16a /compiler/GHC/Core/Subst.hs | |
| parent | 0002db1bf436cbd32f97b659a52b1eee4e8b21db (diff) | |
| download | haskell-wip/T16296.tar.gz | |
Re-engineer the binder-swap transformationwip/T16296
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/Core/Subst.hs')
| -rw-r--r-- | compiler/GHC/Core/Subst.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Subst.hs b/compiler/GHC/Core/Subst.hs index e36e4fb289..2770882d67 100644 --- a/compiler/GHC/Core/Subst.hs +++ b/compiler/GHC/Core/Subst.hs @@ -618,7 +618,7 @@ substIdInfo subst new_id info where old_rules = ruleInfo info old_unf = unfoldingInfo info - nothing_to_do = isEmptyRuleInfo old_rules && not (isFragileUnfolding old_unf) + nothing_to_do = isEmptyRuleInfo old_rules && not (hasCoreUnfolding old_unf) ------------------ -- | Substitutes for the 'Id's within an unfolding |