- Dec 08, 2020
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This patch fixes several aspects of kind inference for data type declarations, especially data /instance/ declarations Specifically 1. In kcConDecls/kcConDecl make it clear that the tc_res_kind argument is only used in the H98 case; and in that case there is no result kind signature; and hence no need for the disgusting splitPiTys in kcConDecls (now thankfully gone). The GADT case is a bit different to before, and much nicer. This is what fixes #18891. See Note [kcConDecls: kind-checking data type decls] 2. Do not look at the constructor decls of a data/newtype instance in tcDataFamInstanceHeader. See GHC.Tc.TyCl.Instance Note [Kind inference for data family instances]. This was a new realisation that arose when doing (1) This causes a few knock-on effects in the tests suite, because we require more information than before in the instance /header/. New user-manual material about this in "Kind inference in data type declarations" and "Kind inference for data/newtype instance declarations". 3. Minor improvement in kcTyClDecl, combining GADT and H98 cases 4. Fix #14111 and #8707 by allowing the header of a data instance to affect kind inferece for the the data constructor signatures; as described at length in Note [GADT return types] in GHC.Tc.TyCl This led to a modest refactoring of the arguments (and argument order) of tcConDecl/tcConDecls. 5. Fix #19000 by inverting the sense of the test in new_locs in GHC.Tc.Solver.Canonical.canDecomposableTyConAppOK.
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- Dec 05, 2020
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- Dec 04, 2020
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Ben Gamari authored
Ensuring that the right toolchain is used.
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- Dec 03, 2020
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Ben Gamari authored
Also be more consistent in quoting.
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- Dec 02, 2020
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Instead of relying on RTS_LINKER_USE_MMAP
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Consolidates munmap calls to ensure consistent error handling.
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Previously most of the uses of mmapForLinker were mapping anonymous memory, resulting in a great deal of unnecessary repetition. Factor this out into a new helper. Also fixes a few places where error checking was missing or suboptimal.
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Now that flattening doesn't produce flattening variables, it's not really flattening anything: it's rewriting. This change also means that the rewriter can no longer be confused the core flattener (in GHC.Core.Unify), which is sometimes used during type-checking.
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This patch redesigns the flattener to simplify type family applications directly instead of using flattening meta-variables and skolems. The key new innovation is the CanEqLHS type and the new CEqCan constraint (Ct). A CanEqLHS is either a type variable or exactly-saturated type family application; either can now be rewritten using a CEqCan constraint in the inert set. Because the flattener no longer reduces all type family applications to variables, there was some performance degradation if a lengthy type family application is now flattened over and over (not making progress). To compensate, this patch contains some extra optimizations in the flattener, leading to a number of performance improvements. Close #18875. Close #18910. There are many extra parts of the compiler that had to be affected in writing this patch: * The family-application cache (formerly the flat-cache) sometimes stores coercions built from Given inerts. When these inerts get kicked out, we must kick out from the cache as well. (This was, I believe, true previously, but somehow never caused trouble.) Kicking out from the cache requires adding a filterTM function to TrieMap. * This patch obviates the need to distinguish "blocking" coercion holes from non-blocking ones (which, previously, arose from CFunEqCans). There is thus some simplification around coercion holes. * Extra commentary throughout parts of the code I read through, to preserve the knowledge I gained while working. * A change in the pure unifier around unifying skolems with other types. Unifying a skolem now leads to SurelyApart, not MaybeApart, as documented in Note [Binding when looking up instances] in GHC.Core.InstEnv. * Some more use of MCoercion where appropriate. * Previously, class-instance lookup automatically noticed that e.g. C Int was a "unifier" to a target [W] C (F Bool), because the F Bool was flattened to a variable. Now, a little more care must be taken around checking for unifying instances. * Previously, tcSplitTyConApp_maybe would split (Eq a => a). This is silly, because (=>) is not a tycon in Haskell. Fixed now, but there are some knock-on changes in e.g. TrieMap code and in the canonicaliser. * New function anyFreeVarsOf{Type,Co} to check whether a free variable satisfies a certain predicate. * Type synonyms now remember whether or not they are "forgetful"; a forgetful synonym drops at least one argument. This is useful when flattening; see flattenView. * The pattern-match completeness checker invokes the solver. This invocation might need to look through newtypes when checking representational equality. Thus, the desugarer needs to keep track of the in-scope variables to know what newtype constructors are in scope. I bet this bug was around before but never noticed. * Extra-constraints wildcards are no longer simplified before printing. See Note [Do not simplify ConstraintHoles] in GHC.Tc.Solver. * Whether or not there are Given equalities has become slightly subtler. See the new HasGivenEqs datatype. * Note [Type variable cycles in Givens] in GHC.Tc.Solver.Canonical explains a significant new wrinkle in the new approach. * See Note [What might match later?] in GHC.Tc.Solver.Interact, which explains the fix to #18910. * The inert_count field of InertCans wasn't actually used, so I removed it. Though I (Richard) did the implementation, Simon PJ was very involved in design and review. This updates the Haddock submodule to avoid #18932 by adding a type signature. ------------------------- Metric Decrease: T12227 T5030 T9872a T9872b T9872c Metric Increase: T9872d -------------------------
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The previous value of 75 meant that a feature branch with more than 75 commits would get spurious CI passes. This affects #18692, but does not fix that ticket, because if a baseline cannot be found, we should fail, not succeed.
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This sets the stage for a later change, where this algorithm will be needed from GHC.Core.InstEnv. This commit also splits GHC.Core.Map into GHC.Core.Map.Type and GHC.Core.Map.Expr, in order to avoid module import cycles with GHC.Core.
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- Dec 01, 2020
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This previously resulted in warnings due to spurious unmap failures.
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This PR concerns the following functions from `Data.Foldable`: * minimum * maximum * sum * product * minimumBy * maximumBy - Default implementations of these functions now use `foldl'` or `foldMap'`. - All have been marked with INLINEABLE to make room for further optimisations.
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- Nov 30, 2020
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See #18973.
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In the past some people have confused ASSERT, which is for checking internal invariants, which CHECK, which should be used when checking things that might fail due to bad input (and therefore should be enabled even in the release compiler). Change some of these cases in the linker to use CHECK.
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Use the GHC wrappers instead of <assert.h>.
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Previously, in an attempt to reduce fragmentation, each new allocator would map a region of M32_MAX_PAGES fresh pages to seed itself. However, this ends up being extremely wasteful since it turns out that we often use fewer than this. Consequently, these pages end up getting freed which, ends up fragmenting our address space more than than we would have if we had naively allocated pages on-demand. Here we refactor m32 to avoid this waste while achieving the fragmentation mitigation previously desired. In particular, we move all page allocation into the global m32_alloc_page, which will pull a page from the free page pool. If the free page pool is empty we then refill it by allocating a region of M32_MAP_PAGES and adding them to the pool. Furthermore, we do away with the initial seeding entirely. That is, the allocator starts with no active pages: pages are rather allocated on an as-needed basis. On the whole this ends up being a pleasingly simple change, simultaneously making m32 more efficient, more robust, and simpler. Fixes #18980.
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- Nov 29, 2020
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See Note [Non-moving GC: Marking evacuated objects].
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The mark thread is not joinable as we detach from it on creation.
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pthread_join returns its error code and apparently doesn't set errno.
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Ensure that the the free variables have been pushed to the update remembered set before we zero the slop.
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After a THROWTO message has been handle the message closure is overwritten by a NULL message. We must ensure that the original closure's pointers continue to be visible to the nonmoving GC.
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When threadPaused blackholes a thunk it calls `OVERWRITING_CLOSURE` to zero the slop for the benefit of the sanity checker. Previously this was done *before* pushing the thunk's free variables to the update remembered set. Consequently we would pull zero'd pointers to the update remembered set.
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This will allow us to back out the allocations per compiler pass from the eventlog. Note that we dump the allocation counter rather than the difference since this will allow us to determine how much work is done *between* `withTiming` blocks.
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- Nov 28, 2020
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Due to #18953.
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Harmonize the internal (big sum type) names of the native vs fixed-sized number primops a bit. (Mainly by renaming the former.) No user-facing names are changed.
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