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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/Core/FVs.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/Core/FVs.hs')
| -rw-r--r-- | compiler/GHC/Core/FVs.hs | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/compiler/GHC/Core/FVs.hs b/compiler/GHC/Core/FVs.hs index 67577bcd9b..6995cc71a1 100644 --- a/compiler/GHC/Core/FVs.hs +++ b/compiler/GHC/Core/FVs.hs @@ -35,7 +35,7 @@ module GHC.Core.FVs ( idFVs, idRuleVars, idRuleRhsVars, stableUnfoldingVars, ruleRhsFreeVars, ruleFreeVars, rulesFreeVars, - rulesFreeVarsDSet, + rulesFreeVarsDSet, mkRuleInfo, ruleLhsFreeIds, ruleLhsFreeIdsList, expr_fvs, @@ -469,6 +469,11 @@ rulesFVs = mapUnionFV ruleFVs rulesFreeVarsDSet :: [CoreRule] -> DVarSet rulesFreeVarsDSet rules = fvDVarSet $ rulesFVs rules +-- | Make a 'RuleInfo' containing a number of 'CoreRule's, suitable +-- for putting into an 'IdInfo' +mkRuleInfo :: [CoreRule] -> RuleInfo +mkRuleInfo rules = RuleInfo rules (rulesFreeVarsDSet rules) + idRuleRhsVars :: (Activation -> Bool) -> Id -> VarSet -- Just the variables free on the *rhs* of a rule idRuleRhsVars is_active id |