- Oct 10, 2023
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The motivation for the flag is given in #21917.
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- Oct 05, 2023
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- Oct 04, 2023
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- Sep 28, 2023
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Fixes #24014.
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- Sep 16, 2023
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As the Lint error in #23952 showed, the function adjustJoinPointType was failing to adjust the FunTyFlag when adjusting the type. I don't think this caused the seg-fault reported in the ticket, but it is definitely. This patch fixes it. It is tricky to come up a small test case; Krzysztof came up with this one, but it only triggers a failure in GHC 9.6.
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- Sep 13, 2023
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Issue #23922 showed that GHC was bogusly eta-reducing a join point. We should never eta-reduce (\x -> j x) to j, if j is a join point. It is extremly difficult to trigger this bug. It took me 45 mins of trying to make a small tests case, here immortalised as T23922a.
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When the user adds a SPEC argument to a function, they are informing us that they expect the function to be specialised. However, previously this instruction could be preempted by the specialised-argument limit (sc_max_args). Fix this. This fixes #14003.
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- Sep 07, 2023
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In the Lint failure in #23938, we start with a coercion Refl :: T a ~R T a, and call mkSelCo (SelTyCon 1 nominal) Refl. The function incorrectly returned Refl :: a ~R a. The returned role should be nominal, according to the SelCo rule: co : (T s1..sn) ~r0 (T t1..tn) r = tyConRole tc r0 i ---------------------------------- SelCo (SelTyCon i r) : si ~r ti In this test case, r is nominal while r0 is representational.
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- Aug 28, 2023
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Simon says this was fixed by commit 59202c80 Author: Sebastian Graf <sebastian.graf@kit.edu> Date: Fri Mar 31 17:35:22 2023 +0200 CorePrep: Eliminate EmptyCase and unsafeEqualityProof in CoreToStg instead We eliminate EmptyCase by way of `coreToStg (Case e _ _ []) = coreToStg e` now. The main reason is that it plays far better in conjunction with eta expansion (as we aim to do for arguments in CorePrep, #23083), because we can discard any arguments, `(case e of {}) eta == case e of {}`, whereas in `(e |> co) eta` it's impossible to discard the argument.
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- Aug 09, 2023
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Previously, we'd only eta expand let bindings and lambdas, now we'll also eta expand arguments such as in T23083: ```hs g f h = f (h `seq` (h $)) ``` Unless `-fpedantic-bottoms` is set, we'll now transform to ```hs g f h = f (\eta -> h eta) ``` in CorePrep. See the new `Note [Eta expansion of arguments in CorePrep]` for the details. We only do this optimisation with -O2 because we saw 2-3% ghc/alloc regressions in T4801 and T5321FD. Fixes #23083.
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A minor improvement to pretty-printing
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- Aug 03, 2023
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Gergő Érdi authored
incoherent instances Fixes #23287
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- Jul 30, 2023
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This MR addresses #22404. There is a big Note Note [Occurrence analysis for join points] that explains it all. Significant changes * New field occ_join_points in OccEnv * The NonRec case of occAnalBind splits into two cases: one for existing join points (which does the special magic for Note [Occurrence analysis for join points], and one for other bindings. * mkOneOcc adds in info from occ_join_points. * All "bring into scope" activity is centralised in the new function `addInScope`. * I made a local data type LocalOcc for use inside the occurrence analyser It is like OccInfo, but lacks IAmDead and IAmALoopBreaker, which in turn makes computationns over it simpler and more efficient. * I found quite a bit of allocation in GHC.Core.Rules.getRules so I optimised it a bit. More minor changes * I found I was using (Maybe Arity) a lot, so I defined a new data type JoinPointHood and used it everwhere. This touches a lot of non-occ-anal files, but it makes everything more perspicuous. * Renamed data constructor WithUsageDetails to WUD, and WithTailUsageDetails to WTUD This also fixes #21128, on the way. --------- Compiler perf ----------- I spent quite a time on performance tuning, so even though it does more than before, the occurrence analyser runs slightly faster on average. Here are the compile-time allocation changes over 0.5% CoOpt_Read(normal) ghc/alloc 766,025,520 754,561,992 -1.5% CoOpt_Singletons(normal) ghc/alloc 759,436,840 762,925,512 +0.5% LargeRecord(normal) ghc/alloc 1,814,482,440 1,799,530,456 -0.8% PmSeriesT(normal) ghc/alloc 68,159,272 67,519,720 -0.9% T10858(normal) ghc/alloc 120,805,224 118,746,968 -1.7% T11374(normal) ghc/alloc 164,901,104 164,070,624 -0.5% T11545(normal) ghc/alloc 79,851,808 78,964,704 -1.1% T12150(optasm) ghc/alloc 73,903,664 71,237,544 -3.6% GOOD T12227(normal) ghc/alloc 333,663,200 331,625,864 -0.6% T12234(optasm) ghc/alloc 52,583,224 52,340,344 -0.5% T12425(optasm) ghc/alloc 81,943,216 81,566,720 -0.5% T13056(optasm) ghc/alloc 294,517,928 289,642,512 -1.7% T13253-spj(normal) ghc/alloc 118,271,264 59,859,040 -49.4% GOOD T15164(normal) ghc/alloc 1,102,630,352 1,091,841,296 -1.0% T15304(normal) ghc/alloc 1,196,084,000 1,166,733,000 -2.5% T15630(normal) ghc/alloc 148,729,632 147,261,064 -1.0% T15703(normal) ghc/alloc 379,366,664 377,600,008 -0.5% T16875(normal) ghc/alloc 32,907,120 32,670,976 -0.7% T17516(normal) ghc/alloc 1,658,001,888 1,627,863,848 -1.8% T17836(normal) ghc/alloc 395,329,400 393,080,248 -0.6% T18140(normal) ghc/alloc 71,968,824 73,243,040 +1.8% T18223(normal) ghc/alloc 456,852,568 453,059,088 -0.8% T18282(normal) ghc/alloc 129,105,576 131,397,064 +1.8% T18304(normal) ghc/alloc 71,311,712 70,722,720 -0.8% T18698a(normal) ghc/alloc 208,795,112 210,102,904 +0.6% T18698b(normal) ghc/alloc 230,320,736 232,697,976 +1.0% BAD T19695(normal) ghc/alloc 1,483,648,128 1,504,702,976 +1.4% T20049(normal) ghc/alloc 85,612,024 85,114,376 -0.6% T21839c(normal) ghc/alloc 415,080,992 410,906,216 -1.0% GOOD T4801(normal) ghc/alloc 247,590,920 250,726,272 +1.3% T6048(optasm) ghc/alloc 95,699,416 95,080,680 -0.6% T783(normal) ghc/alloc 335,323,384 332,988,120 -0.7% T9233(normal) ghc/alloc 709,641,224 685,947,008 -3.3% GOOD T9630(normal) ghc/alloc 965,635,712 948,356,120 -1.8% T9675(optasm) ghc/alloc 444,604,152 428,987,216 -3.5% GOOD T9961(normal) ghc/alloc 303,064,592 308,798,800 +1.9% BAD WWRec(normal) ghc/alloc 503,728,832 498,102,272 -1.1% geo. mean -1.0% minimum -49.4% maximum +1.9% In fact these figures seem to vary between platforms; generally worse on i386 for some reason. The Windows numbers vary by 1% espec in benchmarks where the total allocation is low. But the geom mean stays solidly negative, which is good. The "increase/decrease" list below covers all platforms. The big win on T13253-spj comes because it has a big nest of join points, each occurring twice in the next one. The new occ-anal takes only one iteration of the simplifier to do the inlining; the old one took four. Moreover, we get much smaller code with the new one: New: Result size of Tidy Core = {terms: 429, types: 84, coercions: 0, joins: 14/14} Old: Result size of Tidy Core = {terms: 2,437, types: 304, coercions: 0, joins: 10/10} --------- Runtime perf ----------- No significant changes in nofib results, except a 1% reduction in compiler allocation. Metric Decrease: CoOpt_Read T13253-spj T9233 T9630 T9675 T12150 T21839c LargeRecord MultiComponentModulesRecomp T10421 T13701 T10421 T13701 T12425 Metric Increase: T18140 T9961 T18282 T18698a T18698b T19695
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- Jul 22, 2023
- Jul 15, 2023
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This patch finally (I hope) nails the question of whether (forall a. ty) and (forall a -> ty) are `eqType`: they aren't! There is a long discussion in #22762, plus useful Notes: * Note [ForAllTy and type equality] in GHC.Core.TyCo.Compare * Note [Comparing visiblities] in GHC.Core.TyCo.Compare * Note [ForAllCo] in GHC.Core.TyCo.Rep It also establishes a helpful new invariant for ForAllCo, and ForAllTy, when the bound variable is a CoVar:in that case the visibility must be coreTyLamForAllTyFlag. All this is well documented in revised Notes.
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- Jul 13, 2023
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Found by Simon in ghc/ghc#23567 (comment 507834) The testcase isn't ideal because it doesn't detect the bug in master, unless doNotUnbox is removed as in ghc/ghc#23567 (comment 507692). But I have confirmed that with that modification, it fails before and passes afterwards.
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- Jul 06, 2023
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Fixes #23272
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- Jul 05, 2023
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Fixes #23267
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Currently the Semigroup stimes cycle is resolved in GHC.Base by importing stimes implementations from a hs-boot file. Resolve the cycle using hs-boot files for required classes (Num, Integral) instead. Now stimes can be defined directly in GHC.Base, making inlining and specialization possible. This leads to some new boot files for `GHC.Num` and `GHC.Real`, the methods for those are only used to implement `stimes` so it doesn't appear that these boot files will introduce any new performance traps. Metric Decrease: T13386 T8095 Metric Increase: T13253 T13386 T18698a T18698b T19695 T8095 -
Numerous tests make use of CUSKs (complete user-supplied kinds), a legacy feature scheduled for deprecation. In order to proceed with the said deprecation, the tests have been updated to use SAKS instead (standalone kind signatures). This also allows us to remove the Haskell2010 language pragmas that were added in 115cd3c8 to work around the lack of CUSKs in GHC2021.
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- Jun 29, 2023
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Polymorphic specialisation has led to a number of hard to diagnose incorrect runtime result bugs (see #23469, #23109, #21229, #23445) so this commit introduces a flag `-fpolymorhphic-specialisation` which allows users to turn on this experimental optimisation if they are willing to buy into things going very wrong. Ticket #23469
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- Jun 21, 2023
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Sylvain Henry authored
- Add ghc-interp.js bootstrap script for the JS interpreter - Interactively link and execute iserv code from the ghci package - Incrementally load and run JS code for splices into the running iserv Co-authored-by:Luite Stegeman <stegeman@gmail.com>
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- Jun 14, 2023
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- Jun 13, 2023
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Tracking ticket: #23059 This runs compile_and_run tests with optimised code with bytecode interpreter Changed submodules: hpc, process Co-authored-by:Torsten Schmits <git@tryp.io>
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- May 23, 2023
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The function GHC.Core.Opt.Simplify.Utils.abstractFloats was carelessly calling lookupIdSubst_maybe on a CoVar; but a precondition of the latter is being given an Id. In fact it's harmless to call it on a CoVar, but still, the precondition on lookupIdSubst_maybe makes sense, so I added a test for CoVars. This avoids a crash in a DEBUG compiler, but otherwise has no effect. Fixes #23426.
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- May 15, 2023
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Confusingly, the testsuite mangled the error to say "stray /". We also migrate some tests from grep to grep -E, as it seems the author actually wanted an "POSIX extended" (a.k.a. sane) regex. Background: POSIX specifies 2 "regex" syntaxen: "basic" and "extended". Of these, only "extended" syntax is actually a regular expression. Furthermore, "basic" syntax is inconsistent in its use of the '\' character — sometimes it escapes a regex metacharacter, but sometimes it unescapes it, i.e. it makes an otherwise normal character become a metacharacter. This baffles me and it seems also the authors of these tests. Also, the regex(7) man page (at least on Linux) says "basic" syntax is obsolete. Nearly all modern tools and libraries are consistent in this use of the '\' character (of which many use "extended" syntax by default).
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- May 13, 2023
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As #23307, GHC.Types.Id.Make.shouldUnpackTy was leaving money on the table, failing to unpack arguments that are perfectly unpackable. The fix is pretty easy; see Note [Recursive unboxing]
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- May 12, 2023
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setNominalRole_maybe is supposed to output a nominal coercion. In the SelCo case, it was not updating the stored role to Nominal, causing #23362.
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- May 06, 2023
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Tracking ticket: #20115 MR: !10361 This converts uses of `mkTcRnUnknownMessage` to newly added constructors of `TcRnMessage`. Only addresses the single warning missing from the previous MR.
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- Apr 26, 2023
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In #23208 we observed that the demand signature of a binder occuring in a RULE wasn't unleashed, leading to a transitively used binder being discarded as absent. The solution was to use the same code path that we already use for handling exported bindings. See the changes to `Note [Absence analysis for stable unfoldings and RULES]` for more details. I took the chance to factor out the old notion of a `PlusDmdArg` (a pair of a `VarEnv Demand` and a `Divergence`) into `DmdEnv`, which fits nicely into our existing framework. As a result, I had to touch quite a few places in the code. This refactoring exposed a few small bugs around correct handling of bottoming demand environments. As a result, some strictness signatures now mention uniques that weren't there before which caused test output changes to T13143, T19969 and T22112. But these tests compared whole -ddump-simpl listings which is a very fragile thing to begin with. I changed what exactly they test for based on the symptoms in the corresponding issues. There is a single regression in T18894 because we are more conservative around stable unfoldings now. Unfortunately it is not easily fixed; let's wait until there is a concrete motivation before invest more time. Fixes #23208.
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- Apr 25, 2023
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- Added new section in the GHC user's guide that legends behavior of nested implicit parameter bindings in these two cases: let ?f = 1 in let ?f = 2 in ?f and data T where MkT :: (?f :: Int) => T f :: T -> T -> Int f MkT MkT = ?f - Added new test case to examine this behavior.
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- Apr 20, 2023
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Recent egrep displays the following message, breaking golden tests: egrep: warning: egrep is obsolescent; using grep -E Switch to using "grep -E" instead
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- Apr 04, 2023
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unify_ty was incorrectly saying that F x y ~ T x are surely apart, where F x y is an oversaturated type family and T x is a tyconapp. As a result, the simplifier dropped a live case alternative (#23134).
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- Apr 01, 2023
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There was an outright bug, which Simon fixed in July 2021, as a little side-fix on a complicated patch: ``` commit 6656f016 Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Fri Jul 23 23:57:01 2021 +0100 A bunch of changes related to eta reduction This is a large collection of changes all relating to eta reduction, originally triggered by #18993, but there followed a long saga. Specifics: ...lots of lines omitted... Other incidental changes * Fix a fairly long-standing outright bug in the ApplyToVal case of GHC.Core.Opt.Simplify.mkDupableContWithDmds. I was failing to take the tail of 'dmds' in the recursive call, which meant the demands were All Wrong. I have no idea why this has not caused problems before now. ``` Note this "Fix a fairly longstanding outright bug". This is the specific fix ``` @@ -3552,8 +3556,8 @@ mkDupableContWithDmds env dmds -- let a = ...arg... -- in [...hole...] a -- NB: sc_dup /= OkToDup; that is caught earlier by contIsDupable - do { let (dmd:_) = dmds -- Never fails - ; (floats1, cont') <- mkDupableContWithDmds env dmds cont + do { let (dmd:cont_dmds) = dmds -- Never fails + ; (floats1, cont') <- mkDupableContWithDmds env cont_dmds cont ; let env' = env `setInScopeFromF` floats1 ; (_, se', arg') <- simplArg env' dup se arg ; (let_floats2, arg'') <- makeTrivial env NotTopLevel dmd (fsLit "karg") arg' ``` Ticket #23184 is a report of the bug that this diff fixes.
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- Mar 30, 2023
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- Mar 21, 2023
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CmmCgInfos is needed to write interface files, but the JavaScript backend does not generate it, causing "Name without LFInfo" warnings. This patch adds a conservative but always correct CmmCgInfos when the JavaScript backend is used. Fixes #23053
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- Mar 03, 2023
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Fixes #23026
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- Feb 28, 2023
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As #22998 showed, we were floating an unlifted binding to top level, which breaks a Core invariant. The fix is easy, albeit a little bit conservative. See Note [Care with unlifted bindings] in GHC.Core.Opt.Specialise
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