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* Comments, white space, and rename "InlineRule" to "stable unfolding"Simon Peyton Jones2014-08-291-31/+31
| | | | | | The "InlineRule" is gone now, so this is just making the comments line up with the code. A function does change its name though: updModeForInlineRules --> updModeForStableUnfoldings
* Less voluminous output when printing continuationsSimon Peyton Jones2014-08-281-1/+1
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* Document the maintenance of the let/app invariant in the simplifierSimon Peyton Jones2014-08-071-0/+8
| | | | | | | | | It's not obvious why the simplifier generates code that correctly satisfies the let/app invariant. This patch does some minor refactoring, but the main point is to document pre-conditions to key functions, namely that the rhs passed in satisfies the let/app invariant. There shouldn't be any change in behaviour.
* Add LANGUAGE pragmas to compiler/ source filesHerbert Valerio Riedel2014-05-151-0/+2
| | | | | | | | | | | | | | | | | | In some cases, the layout of the LANGUAGE/OPTIONS_GHC lines has been reorganized, while following the convention, to - place `{-# LANGUAGE #-}` pragmas at the top of the source file, before any `{-# OPTIONS_GHC #-}`-lines. - Moreover, if the list of language extensions fit into a single `{-# LANGUAGE ... -#}`-line (shorter than 80 characters), keep it on one line. Otherwise split into `{-# LANGUAGE ... -#}`-lines for each individual language extension. In both cases, try to keep the enumeration alphabetically ordered. (The latter layout is preferable as it's more diff-friendly) While at it, this also replaces obsolete `{-# OPTIONS ... #-}` pragma occurences by `{-# OPTIONS_GHC ... #-}` pragmas.
* Some typos in commentsGabor Greif2014-04-241-1/+1
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* Don't eta-expand PAPs (fixes Trac #9020)Simon Peyton Jones2014-04-241-11/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | See Note [Do not eta-expand PAPs] in SimplUtils. This has a tremendously good effect on compile times for some simple benchmarks. The test is now where it belongs, in perf/compiler/T9020 (instead of simpl015). I did a nofib run and got essentially zero change except for cacheprof which gets 4% more allocation. I investigated. Turns out that we have instance PP Reg where pp ppm ST_0 = "%st" pp ppm ST_1 = "%st(1)" pp ppm ST_2 = "%st(2)" pp ppm ST_3 = "%st(3)" pp ppm ST_4 = "%st(4)" pp ppm ST_5 = "%st(5)" pp ppm ST_6 = "%st(6)" pp ppm ST_7 = "%st(7)" pp ppm r = "%" ++ map toLower (show r) That (map toLower (show r) does a lot of map/toLowers. But if we inline show we get something like pp ppm ST_0 = "%st" pp ppm ST_1 = "%st(1)" pp ppm ST_2 = "%st(2)" pp ppm ST_3 = "%st(3)" pp ppm ST_4 = "%st(4)" pp ppm ST_5 = "%st(5)" pp ppm ST_6 = "%st(6)" pp ppm ST_7 = "%st(7)" pp ppm EAX = map toLower (show EAX) pp ppm EBX = map toLower (show EBX) ...etc... and all those map/toLower calls can now be floated to top level. This gives a 4% decrease in allocation. But it depends on inlining a pretty big 'show' function. With this new patch we get slightly better eta-expansion, which makes a function look slightly bigger, which just stops it being inlined. The previous behaviour was luck, so I'm not going to worry about losing it. I've added some notes to nofib/Simon-nofib-notes
* Allow a longer demand signature than aritySimon Peyton Jones2014-04-081-3/+2
| | | | | | | | | | See Note [Demand analysis for trivial right-hand sides] in DmdAnal. This allows a function with arity 2 to have a DmdSig with 3 args; which in turn had a knock-on effect, which showed up in the test for Trac #8963. In fact it seems entirely reasonable, so this patch removes the WARN and CoreLint checks that were complaining.
* Implement CallArity analysisJoachim Breitner2014-02-101-1/+3
| | | | | | | | | | | | | This analysis finds out if a let-bound expression with lower manifest arity than type arity is always called with more arguments, as in that case eta-expansion is allowed and often viable. The analysis is very much tailored towards the code generated when foldl is implemented via foldr; without this analysis doing so would be a very bad idea! There are other ways to improve foldr/builder-fusion to cope with foldl, if any of these are implemented then this step can probably be moved to -O2 to save some compilation times. The current impact of adding this phase is just below +2% (measured running GHC's "make").
* Improve eta expansion (again)Simon Peyton Jones2013-11-121-97/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The presenting issue was that we were never eta-expanding f (\x -> case x of (a,b) -> \s -> blah) and that meant we were allocating two lambdas instead of one. See Note [Eta expanding lambdas] in SimplUtils. However I didn't want to eta expand the lambda, and then try all over again for tryEtaExpandRhs. Yet the latter is important in the context of a let-binding it can do simple arity analysis. So I ended up refactoring CallCtxt so that it tells when we are on the RHS of a let. I also moved findRhsArity from SimplUtils to CoreArity. Performance increases nicely. Here are the ones where allocation improved by more than 0.5%. Notice the nice decrease in binary size too. -------------------------------------------------------------------------------- Program Size Allocs Runtime Elapsed TotalMem -------------------------------------------------------------------------------- ansi -2.3% -0.9% 0.00 0.00 +0.0% bspt -2.1% -9.7% 0.01 0.01 -33.3% fasta -1.8% -11.7% -3.4% -3.6% +0.0% fft -1.9% -1.3% 0.06 0.06 +11.1% reverse-complem -1.9% -18.1% -1.9% -2.8% +0.0% sphere -1.8% -4.5% 0.09 0.09 +0.0% transform -1.8% -2.3% -4.6% -3.1% +0.0% -------------------------------------------------------------------------------- Min -3.0% -18.1% -13.9% -14.6% -35.7% Max -1.3% +0.0% +7.7% +7.7% +50.0% Geometric Mean -1.9% -0.6% -2.1% -2.1% -0.2%
* TyposKrzysztof Gogolewski2013-09-231-2/+2
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* Comments onlyGabor Greif2013-08-201-1/+1
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* Implement "roles" into GHC.Richard Eisenberg2013-08-021-1/+1
| | | | | | | | | | | | | | | | Roles are a solution to the GeneralizedNewtypeDeriving type-safety problem. Roles were first described in the "Generative type abstraction" paper, by Stephanie Weirich, Dimitrios Vytiniotis, Simon PJ, and Steve Zdancewic. The implementation is a little different than that paper. For a quick primer, check out Note [Roles] in Coercion. Also see http://ghc.haskell.org/trac/ghc/wiki/Roles and http://ghc.haskell.org/trac/ghc/wiki/RolesImplementation For a more formal treatment, check out docs/core-spec/core-spec.pdf. This fixes Trac #1496, #4846, #7148.
* Make the simplifier propagate strictness through castsSimon Peyton Jones2013-06-061-14/+50
| | | | | | | E.g. (f e1 |> g) e2 If f is strict in two aguments, we want to see that in e2 Hence ArgSpec in SimplUtils
* Comments and white space onlySimon Peyton Jones2013-06-061-0/+1
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* Make 'SPECIALISE instance' work againSimon Peyton Jones2013-05-301-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a long-standing regression (Trac #7797), which meant that in particular the Eq [Char] instance does not get specialised. (The *methods* do, but the dictionary itself doesn't.) So when you call a function f :: Eq a => blah on a string type (ie a=[Char]), 7.6 passes a dictionary of un-specialised methods. This only matters when calling an overloaded function from a specialised context, but that does matter in some programs. I remember (though I cannot find the details) that Nick Frisby discovered this to be the source of some pretty solid performanc regresisons. Anyway it works now. The key change is that a DFunUnfolding now takes a form that is both simpler than before (the DFunArg type is eliminated) and more general: data Unfolding = ... | DFunUnfolding { -- The Unfolding of a DFunId -- See Note [DFun unfoldings] -- df = /\a1..am. \d1..dn. MkD t1 .. tk -- (op1 a1..am d1..dn) -- (op2 a1..am d1..dn) df_bndrs :: [Var], -- The bound variables [a1..m],[d1..dn] df_con :: DataCon, -- The dictionary data constructor (never a newtype datacon) df_args :: [CoreExpr] -- Args of the data con: types, superclasses and methods, } -- in positional order That in turn allowed me to re-enable the DFunUnfolding specialisation in DsBinds. Lots of details here in TcInstDcls: Note [SPECIALISE instance pragmas] I also did some refactoring, in particular to pass the InScopeSet to exprIsConApp_maybe (which in turn means it has to go to a RuleFun). NB: Interface file format has changed!
* typosGabor Greif2013-01-301-2/+2
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* Comments onlySimon Peyton Jones2013-01-221-1/+1
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* Make combine-identical-alternatives work again (Trac #7360)Simon Peyton Jones2012-12-241-59/+68
| | | | | | | | | | | | | | | | Move the "combine indentical alternatives" transformation *before* simplifying the alternatives. For example case x of y [] -> length y (_:_) -> length y } If we look *post* simplification, since 'y' is used in the alterantives, the case binders *might* be (see the keep_occ_info test in Simplify.simplAlt); and hence the combination of the two alteranatives does not happen. But if we do it *pre* simplification there is no problem. This fixes Trac #7360.
* Some alpha renamingIan Lynagh2012-10-161-5/+5
| | | | | Mostly d -> g (matching DynFlag -> GeneralFlag). Also renamed if* to when*, matching the Haskell if/when names
* Make -f(no-)pre-inlining a dynamic flagIan Lynagh2012-10-091-4/+3
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* Whitespace only in simplCore/SimplUtils.lhsIan Lynagh2012-10-091-561/+554
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* Make the opt_UF_* static flags dynamicIan Lynagh2012-10-091-3/+3
| | | | | | | | I also removed the default values from the "Discounts and thresholds" note: most of them were no longer up-to-date. Along the way I added FloatSuffix to the argument parser, analogous to IntSuffix.
* Wibbles to 'simplify the SimplCont data type'Simon Peyton Jones2012-05-091-1/+1
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* Simplify the SimplCont data typeSimon Peyton Jones2012-05-091-61/+69
| | | | | | | * Put the result type in the Stop continuation * No need for the alts type in Select The result is a modest but useful simplification
* Fix overnight build breakage (fix from simonpj)Simon Marlow2012-05-041-3/+1
| | | | compiler/simplCore/SimplUtils.lhs:1668:5-25: Irrefutable pattern failed for pattern ((_, _, rhs1) : _)
* Allow cases with empty alterantivesSimon Peyton Jones2012-05-021-28/+28
| | | | | | | | | | | | | | | | | | | | | | This patch allows, for the first time, case expressions with an empty list of alternatives. Max suggested the idea, and Trac #6067 showed that it is really quite important. So I've implemented the idea, fixing #6067. Main changes * See Note [Empty case alternatives] in CoreSyn * Various foldr1's become foldrs * IfaceCase does not record the type of the alternatives. I added IfaceECase for empty-alternative cases. * Core Lint does not complain about empty cases * MkCore.castBottomExpr constructs an empty-alternative case expression (case e of ty {}) * CoreToStg converts '(case e of {})' to just 'e'
* Revert "Refactoring in CoreUtils/CoreArity"Simon Peyton Jones2012-04-271-5/+5
| | | | | | This reverts commit e3f8557c2aca04cf64eec6a1aacde6e01c0944ff. Sigh. Seg fault.
* Comment out a pprTrace unless DEBUG is on (fix Trac #5929)Simon Peyton Jones2012-04-271-0/+2
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* Refactoring in CoreUtils/CoreAritySimon Peyton Jones2012-04-271-5/+5
| | | | | | | | | | | | | | | | | | | | In the previous commit about "aggressive primops" I wanted a new function CoreUtils.exprCertainlyTerminates. In doing this I ended up with a significant refactoring in CoreUtils. The new structure has quite a lot of nice sharing: exprIsCheap = exprIsCheap' isHNFApp exprIsExpandable = exprIsCheap' isConLikeApp exprIsHNF = exprIsHNFlike isHNFApp exprIsConLike = exprIsHNFlike isConLikeApp exprCertainlyTerminates = exprIsHNFlike isTerminatingApp This patch also does some renaming CheapAppFun --> FunAppAnalyser isCheapApp --> isHNFApp isExpandableApp --> isConLikeApp
* Comments onlySimon Peyton Jones2012-03-301-0/+1
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* Make impossible-alternative-finding code more reusableMax Bolingbroke2012-03-211-90/+10
| | | | | | | | | | | | | | | | Makes the following changes: 1. Generalises the type signatures of some functions relating to alternatives so that the type of "variables" and "expression" is not specified 2. Puts the bulk of the alternative-filtering code into a new function filterAlts (in CoreUtils) that can be used outside of the SimplM monad 3. Allows prepareAlts to return a null alternatives list if none are applicable - it turns out that this case was already handled by the caller (in the simplifier). This should result in a modest optimisation improvement in some cases. Conflicts: compiler/coreSyn/CoreUtils.lhs compiler/simplCore/SimplUtils.lhs
* Move sortQuantVars to MkCoreSimon Peyton Jones2012-02-171-0/+1
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* Remove getDOptsSmpl; use getDynFlags insteadIan Lynagh2012-01-191-2/+2
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* Revert "Add -faggressive-primops plus refactoring in CoreUtils" (#5780)Simon Marlow2012-01-161-5/+5
| | | | This reverts commit 601c983dd0bada6b49bdadd8f172fd4eacac4b0c.
* Add -faggressive-primops plus refactoring in CoreUtilsSimon Peyton Jones2012-01-131-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I'm experimenting with making GHC a bit more aggressive about a) dropping case expressions if the result is unused Simplify.rebuildCase, CaseElim equation b) floating case expressions inwards FloatIn.fiExpr, AnnCase In both cases the new behaviour is gotten with a static (debug) flag -faggressive-primops. The extra "aggression" is to allow discarding and floating in for side-effecting operations. See the new, extensive Note [PrimOp can_fail and has_side_effects] in PrimoOp. When discarding a case with unused binders, in the lifted-type case it's definitely ok if the scrutinee terminates; previously we were checking exprOkForSpeculation, which is significantly worse. So I wanted a new function CoreUtils.exprCertainlyTerminates. In doing this I ended up with a significant refactoring in CoreUtils. The new structure has quite a lot of nice sharing: exprIsCheap = exprIsCheap' isHNFApp exprIsExpandable = exprIsCheap' isConLikeApp exprIsHNF = exprIsHNFlike isHNFApp exprIsConLike = exprIsHNFlike isConLikeApp exprCertainlyTerminates = exprIsHNFlike isTerminatingApp
* GHC gets a new constraint solver. More efficient and smaller in size.Dimitrios Vytiniotis2011-11-161-1/+1
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* Add -fpedantic-bottoms, and document itSimon Peyton Jones2011-11-161-41/+11
| | | | | | I did a bit of refactoring (of course) at the same time. See the discussion in Trac #5587. Most of the real change is in CoreArity.
* Fix CaseIdentity optimisaionSimon Peyton Jones2011-11-161-9/+10
| | | | | | In fixing one bug I'd introduced another; case x of { T -> T; F -> F } wasn't getting optmised! Trivial to fix.
* New kind-polymorphic coreJose Pedro Magalhaes2011-11-111-14/+16
| | | | | | | | | This big patch implements a kind-polymorphic core for GHC. The current implementation focuses on making sure that all kind-monomorphic programs still work in the new core; it is not yet guaranteed that kind-polymorphic programs (using the new -XPolyKinds flag) will work. For more information, see http://haskell.org/haskellwiki/GHC/Kinds
* Fix Trac #5475: another bug in exprAritySimon Peyton Jones2011-11-091-1/+1
| | | | | | | | | As usual it was to do with the handling of bottoms, but this time it wasn't terribly subtle; I was using andArityType (which is designed for case branches) as a cheap short cut for the arity trimming needed with a cast. That did the Wrong Thing for bottoming expressions. Sigh.
* Use -fwarn-tabs when validatingIan Lynagh2011-11-041-0/+7
| | | | | We only use it for "compiler" sources, i.e. not for libraries. Many modules have a -fno-warn-tabs kludge for now.
* Overhaul of infrastructure for profiling, coverage (HPC) and breakpointsSimon Marlow2011-11-021-6/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | User visible changes ==================== Profilng -------- Flags renamed (the old ones are still accepted for now): OLD NEW --------- ------------ -auto-all -fprof-auto -auto -fprof-exported -caf-all -fprof-cafs New flags: -fprof-auto Annotates all bindings (not just top-level ones) with SCCs -fprof-top Annotates just top-level bindings with SCCs -fprof-exported Annotates just exported bindings with SCCs -fprof-no-count-entries Do not maintain entry counts when profiling (can make profiled code go faster; useful with heap profiling where entry counts are not used) Cost-centre stacks have a new semantics, which should in most cases result in more useful and intuitive profiles. If you find this not to be the case, please let me know. This is the area where I have been experimenting most, and the current solution is probably not the final version, however it does address all the outstanding bugs and seems to be better than GHC 7.2. Stack traces ------------ +RTS -xc now gives more information. If the exception originates from a CAF (as is common, because GHC tends to lift exceptions out to the top-level), then the RTS walks up the stack and reports the stack in the enclosing update frame(s). Result: +RTS -xc is much more useful now - but you still have to compile for profiling to get it. I've played around a little with adding 'head []' to GHC itself, and +RTS -xc does pinpoint the problem quite accurately. I plan to add more facilities for stack tracing (e.g. in GHCi) in the future. Coverage (HPC) -------------- * derived instances are now coloured yellow if they weren't used * likewise record field names * entry counts are more accurate (hpc --fun-entry-count) * tab width is now correct (markup was previously off in source with tabs) Internal changes ================ In Core, the Note constructor has been replaced by Tick (Tickish b) (Expr b) which is used to represent all the kinds of source annotation we support: profiling SCCs, HPC ticks, and GHCi breakpoints. Depending on the properties of the Tickish, different transformations apply to Tick. See CoreUtils.mkTick for details. Tickets ======= This commit closes the following tickets, test cases to follow: - Close #2552: not a bug, but the behaviour is now more intuitive (test is T2552) - Close #680 (test is T680) - Close #1531 (test is result001) - Close #949 (test is T949) - Close #2466: test case has bitrotted (doesn't compile against current version of vector-space package)
* Comments onlySimon Peyton Jones2011-08-011-2/+3
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* Eta expand partial applicationsSimon Peyton Jones2011-07-211-4/+24
| | | | | | | | | | | | When we have x = \v -> map g we want to eta-expand to x = \v y -> map g y We weren't doing so, and that led to worse code and, perhaps, #5285. I need to check the latter, but I was certainly seeing one similar error. Anyway this looks like a definite improvement
* Simplify the treatment of RULES in OccurAnalSimon Peyton Jones2011-07-211-5/+6
| | | | | | | | | | I realised that my recently-added cunning stuff about RULES for imported Ids was simply wrong, so this patch removes it. See Note [Rules for imported functions], which explains it all. This patch also does quite a bit of refactoring in the treatment of loop breakers.
* The final batch of changes for the new coercion representationSimon Peyton Jones2011-05-121-0/+8
| | | | | | | | | | | | | | | | | | | | | | * Fix bugs in the packing and unpacking of data constructors with equality predicates in their types * Remove PredCo altogether; instead, coercions between predicated types (like (Eq a, [a]~b) => blah) are treated as if they were precisely their underlying representation type Eq a -> ((~) [a] b) -> blah in this case * Similarly, Type.coreView no longer treats equality predciates specially. * Implement the cast-of-coercion optimisation in Simplify.simplCoercionF Numerous other small bug-fixes and refactorings. Annoyingly, OptCoercion had Windows line endings, and this patch switches to Unix, so it looks as if every line has changed.
* This BIG PATCH contains most of the work for the New Coercion RepresentationSimon Peyton Jones2011-04-191-19/+17
| | | | | | | | | | | | | | See the paper "Practical aspects of evidence based compilation in System FC" * Coercion becomes a data type, distinct from Type * Coercions become value-level things, rather than type-level things, (although the value is zero bits wide, like the State token) A consequence is that a coerion abstraction increases the arity by 1 (just like a dictionary abstraction) * There is a new constructor in CoreExpr, namely Coercion, to inject coercions into terms
* Make -fno-enable-rewrite-rules work properlysimonpj@microsoft.com2011-03-021-7/+13
| | | | | | I'd failed to propagate the Opt_EnableRewriteRules flag properly, which meant that -fno-enable-rewrite-rules didn't disable all rewrites. This patch fixes it.
* Fix a buglet in postInlineUnconditionallysimonpj@microsoft.com2011-01-141-6/+21
| | | | | | Under obscure circumstances (actually only shown up when fixing something else) it was possible for a variable binding to be discarded although it was still used. See Note [Top level and postInlineUnconditionally]
* Add a simple arity analysersimonpj@microsoft.com2010-12-211-1/+94
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | I've wanted to do this for ages, but never gotten around to it. The main notes are in Note [Arity analysis] in SimplUtils. The motivating example for arity analysis is this: f = \x. let g = f (x+1) in \y. ...g... What arity does f have? Really it should have arity 2, but a naive look at the RHS won't see that. You need a fixpoint analysis which says it has arity "infinity" the first time round. This makes things more robust to the way in which you write code. For example, see Trac #4474 which is fixed by this change. Not a huge difference, but worth while: Program Size Allocs Runtime Elapsed -------------------------------------------------------------------------------- Min -0.4% -2.2% -10.0% -10.0% Max +2.7% +0.3% +7.1% +6.9% Geometric Mean -0.3% -0.2% -2.1% -2.2% I don't really believe the runtime numbers, because the machine was busy, but the bottom line is that not much changes, and what does change reliably (allocation and size) is in the right direction.
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