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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Simon Peyton Jones pushed to branch wip/T23070-dicts at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
Commits:
</h4>
<ul>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b56d737974f55933a35c911e8a81ee6147b4a542">b56d7379</a></strong>
<div>
<span> by Sylvain Henry </span> <i> at 2023-05-22T14:21:22-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>NCG: remove useless .align directive (#20758)
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/15b93d2f89464800465afa3a35151b904bddc730">15b93d2f</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-05-22T14:21:58-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Add test for #23156
This program had exponential typechecking time in GHC 9.4 and 9.6
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7aaea60ba62a2a421943d449abb42214fc971685">7aaea60b</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-05-22T20:34:52+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Add the SolverStage monad
This refactoring makes a substantial improvement in the
structure of the type-checker's constraint solver: #23070.
Specifically:
* Introduced the SolverStage monad. See GHC.Tc.Solver.Monad
Note [The SolverStage monad]
* Make each solver pipeline (equalities, dictionaries, irreds etc)
deal with updating the inert set, as a separate SolverStage. There
is sometimes special stuff to do, and it means that each full
pipeline can have type SolverStage Void, indicating that they never
return anything.
* Made GHC.Tc.Solver.Equality.zonkEqTypes into a SolverStage. Much nicer.
* Combined the remnants of GHC.Tc.Solver.Canonical and
GHC.Tc.Solver.Interact into a new module GHC.Tc.Solver.Solve.
(Interact and Canonical are removed.)
* Gave the same treatment to dictionary and irred constraints
as I have already done for equality constraints:
* New types (akin to EqCt): IrredCt and DictCt
* Ct is now just a simple sum type
data Ct
= CDictCan DictCt
| CIrredCan IrredCt
| CEqCan EqCt
| CQuantCan QCInst
| CNonCanonical CtEvidence
* inert_dicts can now have the better type DictMap DictCt, instead of
DictMap Ct; and similarly inert_irreds.
* Significantly simplified the treatment of implicit parameters.
Previously we had a number of special cases
* interactGivenIP, an entire function
* special case in maybeKickOut
* special case in findDict, when looking up dictionaries
But actually it's simpler than that. When adding a new Given, implicit
parameter constraint to the InertSet, we just need to kick out any
existing inert constraints that mention that implicit parameter.
The main work is done in GHC.Tc.Solver.InertSet.delIPDict, along with
its auxiliary GHC.Core.Predicate.mentionsIP.
See Note [Shadowing of implicit parameters] in GHC.Tc.Solver.Dict.
* Add a new fast-path in GHC.Tc.Errors.Hole.tcCheckHoleFit.
See Note [Fast path for tcCheckHoleFit]. This is a big win in some cases:
test hard_hole_fits gets nearly 40% faster (at compile time).
* Add a new fast-path for solving /boxed/ equality constraints
(t1 ~ t2). See Note [Solving equality classes] in GHC.Tc.Solver.Dict.
This makes a big difference too: test T17836 compiles 40% faster.
* Implement the PermissivePlan of #23413, which concerns what happens with
insoluble Givens. Our previous treatment was wildly inconsistent as that
ticket pointed out.
A part of this, I simplified GHC.Tc.Validity.checkAmbiguity: now we simply
don't run the ambiguity check at all if -XAllowAmbiguousTypes is on.
Smaller points:
* In `GHC.Tc.Errors.misMatchOrCND` instead of having a special case for
insoluble /occurs/ checks, broaden in to all insouluble constraints.
Just generally better. See Note [Insoluble mis-match] in that module.
As noted above, compile time perf gets better. Here are the changes
over 0.5% on Fedora. (The figures are slightly larger on Windows for
some reason.)
Metrics: compile_time/bytes allocated
-------------------------------------
LargeRecord(normal) -0.9%
MultiLayerModulesTH_OneShot(normal) +0.5%
T11822(normal) -0.6%
T12227(normal) -1.8% GOOD
T12545(normal) -0.5%
T13035(normal) -0.6%
T15703(normal) -1.4% GOOD
T16875(normal) -0.5%
T17836(normal) -40.7% GOOD
T17836b(normal) -12.3% GOOD
T17977b(normal) -0.5%
T5837(normal) -1.1%
T8095(normal) -2.7% GOOD
T9020(optasm) -1.1%
hard_hole_fits(normal) -37.0% GOOD
geo. mean -1.3%
minimum -40.7%
maximum +0.5%
Metric Decrease:
T12227
T15703
T17836
T17836b
T8095
hard_hole_fits
LargeRecord
T9198
T13035
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/189e496c8393575ba84cb1909fd03119be8af379">189e496c</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-05-22T20:34:52+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Avoid an assertion failure in abstractFloats
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.
</pre>
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<h4 style="margin-top: 10px; margin-bottom: 10px;">
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<a href="#8a5cd068459120cddf3814e7b9e02003b87647ba">
compiler/GHC/Builtin/Types/Prim.hs
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<a href="#0c06b80d12937afa0db5ee9903e4d2be2f146d29">
compiler/GHC/CmmToAsm/AArch64/Ppr.hs
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<a href="#335d279236d65dcf13f2bab3891e515cb803203c">
compiler/GHC/CmmToAsm/X86/Ppr.hs
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<a href="#182d6a315e784018aa9c8b2ad736036b97bd5d48">
compiler/GHC/Core.hs
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<a href="#5596bb0f228bd2a308c4391df97375ae879430a8">
compiler/GHC/Core/InstEnv.hs
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<a href="#c3967bb9d3e8f5aae2dd111b5a335b48c21c1999">
compiler/GHC/Core/Opt/Arity.hs
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compiler/GHC/Core/Opt/Simplify/Utils.hs
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compiler/GHC/Core/Predicate.hs
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compiler/GHC/Core/TyCo/Compare.hs
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compiler/GHC/Core/TyCon.hs
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compiler/GHC/Core/Type.hs
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compiler/GHC/Core/Unify.hs
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compiler/GHC/HsToCore/Binds.hs
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compiler/GHC/Tc/Deriv/Generate.hs
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compiler/GHC/Tc/Errors.hs
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compiler/GHC/Tc/Errors/Hole.hs
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compiler/GHC/Tc/Errors/Types.hs
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compiler/GHC/Tc/Gen/App.hs
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compiler/GHC/Tc/Gen/HsType.hs
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compiler/GHC/Tc/Gen/Pat.hs
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compiler/GHC/Tc/Gen/Rule.hs
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compiler/GHC/Tc/Instance/Class.hs
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compiler/GHC/Tc/Instance/Typeable.hs
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compiler/GHC/Tc/Solver.hs
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compiler/GHC/Tc/Solver/Dict.hs
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The diff was not included because it is too large.
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