1. 31 Jan, 2020 2 commits
    • Ömer Sinan Ağacan's avatar
      Do CafInfo/SRT analysis in Cmm · c846618a
      Ömer Sinan Ağacan authored
      This patch removes all CafInfo predictions and various hacks to preserve
      predicted CafInfos from the compiler and assigns final CafInfos to
      interface Ids after code generation. SRT analysis is extended to support
      static data, and Cmm generator is modified to allow generating
      static_link fields after SRT analysis.
      
      This also fixes `-fcatch-bottoms`, which introduces error calls in case
      expressions in CorePrep, which runs *after* CoreTidy (which is where we
      decide on CafInfos) and turns previously non-CAFFY things into CAFFY.
      
      Fixes #17648
      Fixes #9718
      
      Evaluation
      ==========
      
      NoFib
      -----
      
      Boot with: `make boot mode=fast`
      Run: `make mode=fast EXTRA_RUNTEST_OPTS="-cachegrind" NoFibRuns=1`
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs    Instrs     Reads    Writes
      --------------------------------------------------------------------------------
                   CS          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  CSD          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                   FS          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                    S          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                   VS          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  VSD          -0.0%      0.0%     -0.0%     -0.0%     -0.5%
                  VSM          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 anna          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                 ansi          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 atom          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               awards          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               banner          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
           bernouilli          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         binary-trees          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                boyer          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               boyer2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 bspt          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            cacheprof          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             calendar          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             cichelli          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              circsim          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             clausify          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
        comp_lab_zift          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             compress          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            compress2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
          constraints          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         cryptarithm1          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         cryptarithm2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  cse          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         digits-of-e1          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         digits-of-e2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               dom-lt          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                eliza          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                event          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
          exact-reals          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               exp3_8          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               expert          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
       fannkuch-redux          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                fasta          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  fem          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  fft          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 fft2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             fibheaps          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 fish          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                fluid          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               fulsom          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               gamteb          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  gcd          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
          gen_regexps          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               genfft          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                   gg          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 grep          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               hidden          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  hpg          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  ida          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                infer          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              integer          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            integrate          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         k-nucleotide          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                kahan          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              knights          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               lambda          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
           last-piece          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 lcss          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 life          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 lift          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               linear          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
            listcompr          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             listcopy          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             maillist          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               mandel          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              mandel2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 mate          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              minimax          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              mkhprog          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
           multiplier          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               n-body          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             nucleic2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 para          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            paraffins          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               parser          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
              parstof          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  pic          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             pidigits          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                power          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               pretty          -0.0%      0.0%     -0.3%     -0.4%     -0.4%
               primes          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            primetest          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               prolog          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               puzzle          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               queens          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              reptile          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
      reverse-complem          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              rewrite          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 rfib          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  rsa          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  scc          -0.0%      0.0%     -0.3%     -0.5%     -0.4%
                sched          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  scs          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               simple          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                solid          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              sorting          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
        spectral-norm          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               sphere          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
               symalg          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  tak          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            transform          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             treejoin          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            typecheck          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
              veritas          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 wang          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
            wave4main          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         wheel-sieve1          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
         wheel-sieve2          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 x2n1          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
      --------------------------------------------------------------------------------
                  Min          -0.1%      0.0%     -0.3%     -0.5%     -0.5%
                  Max          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
       Geometric Mean          -0.0%     -0.0%     -0.0%     -0.0%     -0.0%
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs    Instrs     Reads    Writes
      --------------------------------------------------------------------------------
              circsim          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
          constraints          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             fibheaps          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
             gc_bench          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 hash          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 lcss          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                power          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
           spellcheck          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
      --------------------------------------------------------------------------------
                  Min          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  Max          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
       Geometric Mean          -0.0%     +0.0%     -0.0%     -0.0%     -0.0%
      
      Manual inspection of programs in testsuite/tests/programs
      ---------------------------------------------------------
      
      I built these programs with a bunch of dump flags and `-O` and compared
      STG, Cmm, and Asm dumps and file sizes.
      
      (Below the numbers in parenthesis show number of modules in the program)
      
      These programs have identical compiler (same .hi and .o sizes, STG, and
      Cmm and Asm dumps):
      
      - Queens (1), andre_monad (1), cholewo-eval (2), cvh_unboxing (3),
        andy_cherry (7), fun_insts (1), hs-boot (4), fast2haskell (2),
        jl_defaults (1), jq_readsPrec (1), jules_xref (1), jtod_circint (4),
        jules_xref2 (1), lennart_range (1), lex (1), life_space_leak (1),
        bargon-mangler-bug (7), record_upd (1), rittri (1), sanders_array (1),
        strict_anns (1), thurston-module-arith (2), okeefe_neural (1),
        joao-circular (6), 10queens (1)
      
      Programs with different compiler outputs:
      
      - jl_defaults (1): For some reason GHC HEAD marks a lot of top-level
        `[Int]` closures as CAFFY for no reason. With this patch we no longer
        make them CAFFY and generate less SRT entries. For some reason Main.o
        is slightly larger with this patch (1.3%) and the executable sizes are
        the same. (I'd expect both to be smaller)
      
      - launchbury (1): Same as jl_defaults: top-level `[Int]` closures marked
        as CAFFY for no reason. Similarly `Main.o` is 1.4% larger but the
        executable sizes are the same.
      
      - galois_raytrace (13): Differences are in the Parse module. There are a
        lot, but some of the changes are caused by the fact that for some
        reason (I think a bug) GHC HEAD marks the dictionary for `Functor
        Identity` as CAFFY. Parse.o is 0.4% larger, the executable size is the
        same.
      
      - north_array: We now generate less SRT entries because some of array
        primops used in this program like `NewArrayOp` get eliminated during
        Stg-to-Cmm and turn some CAFFY things into non-CAFFY. Main.o gets 24%
        larger (9224 bytes from 9000 bytes), executable sizes are the same.
      
      - seward-space-leak: Difference in this program is better shown by this
        smaller example:
      
            module Lib where
      
            data CDS
              = Case [CDS] [(Int, CDS)]
              | Call CDS CDS
      
            instance Eq CDS where
              Case sels1 rets1 == Case sels2 rets2 =
                  sels1 == sels2 && rets1 == rets2
              Call a1 b1 == Call a2 b2 =
                  a1 == a2 && b1 == b2
              _ == _ =
                  False
      
         In this program GHC HEAD builds a new SRT for the recursive group of
         `(==)`, `(/=)` and the dictionary closure. Then `/=` points to `==`
         in its SRT field, and `==` uses the SRT object as its SRT. With this
         patch we use the closure for `/=` as the SRT and add `==` there. Then
         `/=` gets an empty SRT field and `==` points to `/=` in its SRT
         field.
      
         This change looks fine to me.
      
         Main.o gets 0.07% larger, executable sizes are identical.
      
      head.hackage
      ------------
      
      head.hackage's CI script builds 428 packages from Hackage using this
      patch with no failures.
      
      Compiler performance
      --------------------
      
      The compiler perf tests report that the compiler allocates slightly more
      (worst case observed so far is 4%). However most programs in the test
      suite are small, single file programs. To benchmark compiler performance
      on something more realistic I build Cabal (the library, 236 modules)
      with different optimisation levels. For the "max residency" row I run
      GHC with `+RTS -s -A100k -i0 -h` for more accurate numbers. Other rows
      are generated with just `-s`. (This is because `-i0` causes running GC
      much more frequently and as a result "bytes copied" gets inflated by
      more than 25x in some cases)
      
      * -O0
      
      |                 | GHC HEAD       | This MR        | Diff   |
      | --------------- | -------------- | -------------- | ------ |
      | Bytes allocated | 54,413,350,872 | 54,701,099,464 | +0.52% |
      | Bytes copied    |  4,926,037,184 |  4,990,638,760 | +1.31% |
      | Max residency   |    421,225,624 |    424,324,264 | +0.73% |
      
      * -O1
      
      |                 | GHC HEAD        | This MR         | Diff   |
      | --------------- | --------------- | --------------- | ------ |
      | Bytes allocated | 245,849,209,992 | 246,562,088,672 | +0.28% |
      | Bytes copied    |  26,943,452,560 |  27,089,972,296 | +0.54% |
      | Max residency   |     982,643,440 |     991,663,432 | +0.91% |
      
      * -O2
      
      |                 | GHC HEAD        | This MR         | Diff   |
      | --------------- | --------------- | --------------- | ------ |
      | Bytes allocated | 291,044,511,408 | 291,863,910,912 | +0.28% |
      | Bytes copied    |  37,044,237,616 |  36,121,690,472 | -2.49% |
      | Max residency   |   1,071,600,328 |   1,086,396,256 | +1.38% |
      
      Extra compiler allocations
      --------------------------
      
      Runtime allocations of programs are as reported above (NoFib section).
      
      The compiler now allocates more than before. Main source of allocation
      in this patch compared to base commit is the new SRT algorithm
      (GHC.Cmm.Info.Build). Below is some of the extra work we do with this
      patch, numbers generated by profiled stage 2 compiler when building a
      pathological case (the test 'ManyConstructors') with '-O2':
      
      - We now sort the final STG for a module, which means traversing the
        entire program, generating free variable set for each top-level
        binding, doing SCC analysis, and re-ordering the program. In
        ManyConstructors this step allocates 97,889,952 bytes.
      
      - We now do SRT analysis on static data, which in a program like
        ManyConstructors causes analysing 10,000 bindings that we would
        previously just skip. This step allocates 70,898,352 bytes.
      
      - We now maintain an SRT map for the entire module as we compile Cmm
        groups:
      
            data ModuleSRTInfo = ModuleSRTInfo
              { ...
              , moduleSRTMap :: SRTMap
              }
      
         (SRTMap is just a strict Map from the 'containers' library)
      
         This map gets an entry for most bindings in a module (exceptions are
         THUNKs and CAFFY static functions). For ManyConstructors this map
         gets 50015 entries.
      
      - Once we're done with code generation we generate a NameSet from SRTMap
        for the non-CAFFY names in the current module. This set gets the same
        number of entries as the SRTMap.
      
      - Finally we update CafInfos in ModDetails for the non-CAFFY Ids, using
        the NameSet generated in the previous step. This usually does the
        least amount of allocation among the work listed here.
      
      Only place with this patch where we do less work in the CAF analysis in
      the tidying pass (CoreTidy). However that doesn't save us much, as the
      pass still needs to traverse the whole program and update IdInfos for
      other reasons. Only thing we don't here do is the `hasCafRefs` pass over
      the RHS of bindings, which is a stateless pass that returns a boolean
      value, so it doesn't allocate much.
      
      (Metric changes blow are all increased allocations)
      
      Metric changes
      --------------
      
      Metric Increase:
          ManyAlternatives
          ManyConstructors
          T13035
          T14683
          T1969
          T9961
      c846618a
    • Ben Gamari's avatar
      rename: Eliminate usage of mkVarOccUnique · 942c7148
      Ben Gamari authored
      Replacing it with `newSysName`. Fixes #17061.
      942c7148
  2. 27 Jan, 2020 2 commits
    • Tom Ellis's avatar
      Disable two warnings for files that trigger them · 4bada77d
      Tom Ellis authored
      incomplete-uni-patterns and incomplete-record-updates will be in -Wall at a
      future date, so prepare for that by disabling those warnings on files that
      trigger them.
      4bada77d
    • Ryan Scott's avatar
      Use splitLHs{ForAll,Sigma}TyInvis throughout the codebase · 1132602f
      Ryan Scott authored
      Richard points out in #17688 that we use `splitLHsForAllTy` and
      `splitLHsSigmaTy` in places that we ought to be using the
      corresponding `-Invis` variants instead, identifying two bugs
      that are caused by this oversight:
      
      * Certain TH-quoted type signatures, such as those that appear in
        quoted `SPECIALISE` pragmas, silently turn visible `forall`s into
        invisible `forall`s.
      * When quoted, the type `forall a -> (a ~ a) => a` will turn into
        `forall a -> a` due to a bug in `DsMeta.repForall` that drops
        contexts that follow visible `forall`s.
      
      These are both ultimately caused by the fact that `splitLHsForAllTy`
      and `splitLHsSigmaTy` split apart visible `forall`s in addition to
      invisible ones. This patch cleans things up:
      
      * We now use `splitLHsForAllTyInvis` and `splitLHsSigmaTyInvis`
        throughout the codebase. Relatedly, the `splitLHsForAllTy` and
        `splitLHsSigmaTy` have been removed, as they are easy to misuse.
      * `DsMeta.repForall` now only handles invisible `forall`s to reduce
        the chance for confusion with visible `forall`s, which need to be
        handled differently. I also renamed it from `repForall` to
        `repForallT` to emphasize that its distinguishing characteristic
        is the fact that it desugars down to `L.H.TH.Syntax.ForallT`.
      
      Fixes #17688.
      1132602f
  3. 25 Jan, 2020 5 commits
    • Ryan Scott's avatar
      Do not bring visible foralls into scope in hsScopedTvs · 0940b59a
      Ryan Scott authored
      Previously, `hsScopedTvs` (and its cousin `hsWcScopedTvs`) pretended
      that visible dependent quantification could not possibly happen at
      the term level, and cemented that assumption with an `ASSERT`:
      
      ```hs
          hsScopedTvs (HsForAllTy { hst_fvf = vis_flag, ... }) =
            ASSERT( vis_flag == ForallInvis )
            ...
      ```
      
      It turns out that this assumption is wrong. You can end up tripping
      this `ASSERT` if you stick it to the man and write a type for a term
      that uses visible dependent quantification anyway, like in this
      example:
      
      ```hs
      {-# LANGUAGE ScopedTypeVariables #-}
      
      x :: forall a -> a -> a
      x = x
      ```
      
      That won't typecheck, but that's not the point. Before the
      typechecker has a chance to reject this, the renamer will try
      to use `hsScopedTvs` to bring `a` into scope over the body of `x`,
      since `a` is quantified by a `forall`. This, in turn, causes the
      `ASSERT` to fail. Bummer.
      
      Instead of walking on this dangerous ground, this patch makes GHC
      adopt a more hardline stance by pattern-matching directly on
      `ForallInvis` in `hsScopedTvs`:
      
      ```hs
          hsScopedTvs (HsForAllTy { hst_fvf = ForallInvis, ... }) = ...
      ```
      
      Now `a` will not be brought over the body of `x` at all (which is how
      it should be), there's no chance of the `ASSERT` failing anymore (as
      it's gone), and best of all, the behavior of `hsScopedTvs` does not
      change. Everyone wins!
      
      Fixes #17687.
      0940b59a
    • Sylvain Henry's avatar
      Module hierarchy: Cmm (cf #13009) · 6e2d9ee2
      Sylvain Henry authored
      6e2d9ee2
    • Ryan Scott's avatar
      Handle local fixity declarations in DsMeta properly · c3fde723
      Ryan Scott authored
      `DsMeta.rep_sig` used to skip over `FixSig` entirely, which had the
      effect of causing local fixity declarations to be dropped when quoted
      in Template Haskell. But there is no good reason for this state of
      affairs, as the code in `DsMeta.repFixD` (which handles top-level
      fixity declarations) handles local fixity declarations just fine.
      This patch factors out the necessary parts of `repFixD` so that they
      can be used in `rep_sig` as well.
      
      There was one minor complication: the fixity signatures for class
      methods in each `HsGroup` were stored both in `FixSig`s _and_ the
      list of `LFixitySig`s for top-level fixity signatures, so I needed
      to take action to prevent fixity signatures for class methods being
      converted to `Dec`s twice. I tweaked `RnSource.add` to avoid putting
      these fixity signatures in two places and added
      `Note [Top-level fixity signatures in an HsGroup]` in `GHC.Hs.Decls`
      to explain the new design.
      
      Fixes #17608. Bumps the Haddock submodule.
      c3fde723
    • Sebastian Graf's avatar
      PmCheck: Properly handle constructor-bound type variables · 86966d48
      Sebastian Graf authored
      In !2192 (comment 246551)
      Simon convinced me that ignoring type variables existentially bound by
      data constructors have to be the same way as value binders.
      
      Sadly I couldn't think of a regression test, but I'm confident that this
      change strictly improves on the status quo.
      86966d48
    • Sebastian Graf's avatar
      PmCheck: Formulate as translation between Clause Trees · 8038cbd9
      Sebastian Graf authored
      We used to check `GrdVec`s arising from multiple clauses and guards in
      isolation. That resulted in a split between `pmCheck` and
      `pmCheckGuards`, the implementations of which were similar, but subtly
      different in detail. Also the throttling mechanism described in
      `Note [Countering exponential blowup]` ultimately got quite complicated
      because it had to cater for both checking functions.
      
      This patch realises that pattern match checking doesn't just consider
      single guarded RHSs, but that it's always a whole set of clauses, each
      of which can have multiple guarded RHSs in turn. We do so by
      translating a list of `Match`es to a `GrdTree`:
      
      ```haskell
      data GrdTree
        = Rhs !RhsInfo
        | Guard !PmGrd !GrdTree      -- captures lef-to-right  match semantics
        | Sequence !GrdTree !GrdTree -- captures top-to-bottom match semantics
        | Empty                      -- For -XEmptyCase, neutral element of Sequence
      ```
      
      Then we have a function `checkGrdTree` that matches a given `GrdTree`
      against an incoming set of values, represented by `Deltas`:
      
      ```haskell
      checkGrdTree :: GrdTree -> Deltas -> CheckResult
      ...
      ```
      
      Throttling is isolated to the `Sequence` case and becomes as easy as one
      would expect: When the union of uncovered values becomes too big, just
      return the original incoming `Deltas` instead (which is always a
      superset of the union, thus a sound approximation).
      
      The returned `CheckResult` contains two things:
      
      1. The set of values that were not covered by any of the clauses, for
         exhaustivity warnings.
      2. The `AnnotatedTree` that enriches the syntactic structure of the
         input program with divergence and inaccessibility information.
      
      This is `AnnotatedTree`:
      
      ```haskell
      data AnnotatedTree
        = AccessibleRhs !RhsInfo
        | InaccessibleRhs !RhsInfo
        | MayDiverge !AnnotatedTree
        | SequenceAnn !AnnotatedTree !AnnotatedTree
        | EmptyAnn
      ```
      
      Crucially, `MayDiverge` asserts that the tree may force diverging
      values, so not all of its wrapped clauses can be redundant.
      
      While the set of uncovered values can be used to generate the missing
      equations for warning messages, redundant and proper inaccessible
      equations can be extracted from `AnnotatedTree` by
      `redundantAndInaccessibleRhss`.
      
      For this to work properly, the interface to the Oracle had to change.
      There's only `addPmCts` now, which takes a bag of `PmCt`s. There's a
      whole bunch of `PmCt` variants to replace the different oracle functions
      from before.
      
      The new `AnnotatedTree` structure allows for more accurate warning
      reporting (as evidenced by a number of changes spread throughout GHC's
      code base), thus we fix #17465.
      
      Fixes #17646 on the go.
      
      Metric Decrease:
          T11822
          T9233
          PmSeriesS
          haddock.compiler
      8038cbd9
  4. 20 Jan, 2020 1 commit
  5. 16 Jan, 2020 4 commits
    • Adam Wespiser's avatar
      replace dead html link (fixes #17661) · f416fe64
      Adam Wespiser authored
      f416fe64
    • John Ericson's avatar
      Remove special case case of bool during STG -> C-- · 1ff55226
      John Ericson authored
      Allow removing the no longer needed cgPrimOp, getting rid of a small a
      small layer violation too.
      
      Change which made the special case no longer needed was #6135 /
      6579a6c7, which dates back to 2013,
      making me feel better.
      1ff55226
    • John Ericson's avatar
      Get rid of OpDest · ee5d63f4
      John Ericson authored
      `OpDest` was basically a defunctionalization. Just turn the code that
      cased on it into those functions, and call them directly.
      ee5d63f4
    • John Ericson's avatar
      Handle TagToEnum in the same big case as the other primops · 22c0bdc3
      John Ericson authored
      Before, it was a panic because it was handled above. But there must have
      been an error in my reasoning (another caller?) because #17442 reported
      the panic was hit.
      
      But, rather than figuring out what happened, I can just make it
      impossible by construction. By adding just a bit more bureaucracy in the
      return types, I can handle TagToEnum in the same case as all the others,
      so the big case is is now total, and the panic is removed.
      
      Fixes #17442
      22c0bdc3
  6. 13 Jan, 2020 2 commits
  7. 08 Jan, 2020 2 commits
  8. 07 Jan, 2020 1 commit
    • Ryan Scott's avatar
      Monomorphize HsModule to GhcPs (#17642) · b69a3460
      Ryan Scott authored
      Analyzing the call sites for `HsModule` reveals that it is only ever
      used with parsed code (i.e., `GhcPs`). This simplifies `HsModule` by
      concretizing its `pass` parameter to always be `GhcPs`.
      
      Fixes #17642.
      b69a3460
  9. 06 Jan, 2020 1 commit
  10. 04 Jan, 2020 1 commit
  11. 31 Dec, 2019 1 commit
  12. 18 Dec, 2019 1 commit
    • Sylvain Henry's avatar
      Add GHC-API logging hooks · 58655b9d
      Sylvain Henry authored
      * Add 'dumpAction' hook to DynFlags.
      
      It allows GHC API users to catch dumped intermediate codes and
      information. The format of the dump (Core, Stg, raw text, etc.) is now
      reported allowing easier automatic handling.
      
      * Add 'traceAction' hook to DynFlags.
      
      Some dumps go through the trace mechanism (for instance unfoldings that
      have been considered for inlining). This is problematic because:
      1) dumps aren't written into files even with -ddump-to-file on
      2) dumps are written on stdout even with GHC API
      3) in this specific case, dumping depends on unsafe globally stored
      DynFlags which is bad for GHC API users
      
      We introduce 'traceAction' hook which allows GHC API to catch those
      traces and to avoid using globally stored DynFlags.
      
      * Avoid dumping empty logs via dumpAction/traceAction (but still write
      empty files to keep the existing behavior)
      58655b9d
  13. 17 Dec, 2019 1 commit
    • Krzysztof Gogolewski's avatar
      Use "OrCoVar" functions less · 75355fde
      Krzysztof Gogolewski authored
      As described in #17291, we'd like to separate coercions and expressions
      in a more robust fashion.
      This is a small step in this direction.
      
      - `mkLocalId` now panicks on a covar.
        Calls where this was not the case were changed to `mkLocalIdOrCoVar`.
      - Don't use "OrCoVar" functions in places where we know the type is
        not a coercion.
      75355fde
  14. 09 Dec, 2019 1 commit
    • Gabor Greif's avatar
      Fix comment typos · d46a72e1
      Gabor Greif authored
      The below is only necessary to fix the CI perf fluke that
      happened in 9897e8c8:
      -------------------------
      Metric Decrease:
          T5837
          T6048
          T9020
          T12425
          T12234
          T13035
          T12150
          Naperian
      -------------------------
      d46a72e1
  15. 07 Dec, 2019 1 commit
    • Gabor Greif's avatar
      Implement pointer tagging for big families (#14373) · 9897e8c8
      Gabor Greif authored
      Formerly we punted on these and evaluated constructors always got a tag
      of 1.
      
      We now cascade switches because we have to check the tag first and when
      it is MAX_PTR_TAG then get the precise tag from the info table and
      switch on that. The only technically tricky part is that the default
      case needs (logical) duplication. To do this we emit an extra label for
      it and branch to that from the second switch. This avoids duplicated
      codegen.
      
      Here's a simple example of the new code gen:
      
          data D = D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8
      
      On a 64-bit system previously all constructors would be tagged 1. With
      the new code gen D7 and D8 are tagged 7:
      
          [Lib.D7_con_entry() {
               ...
               {offset
                 c1eu: // global
                     R1 = R1 + 7;
                     call (P64[Sp])(R1) args: 8, res: 0, upd: 8;
               }
           }]
      
          [Lib.D8_con_entry() {
               ...
               {offset
                 c1ez: // global
                     R1 = R1 + 7;
                     call (P64[Sp])(R1) args: 8, res: 0, upd: 8;
               }
           }]
      
      When switching we now look at the info table only when the tag is 7. For
      example, if we derive Enum for the type above, the Cmm looks like this:
      
          c2Le:
              _s2Js::P64 = R1;
              _c2Lq::P64 = _s2Js::P64 & 7;
              switch [1 .. 7] _c2Lq::P64 {
                  case 1 : goto c2Lk;
                  case 2 : goto c2Ll;
                  case 3 : goto c2Lm;
                  case 4 : goto c2Ln;
                  case 5 : goto c2Lo;
                  case 6 : goto c2Lp;
                  case 7 : goto c2Lj;
              }
      
          // Read info table for tag
          c2Lj:
              _c2Lv::I64 = %MO_UU_Conv_W32_W64(I32[I64[_s2Js::P64 & (-8)] - 4]);
              if (_c2Lv::I64 != 6) goto c2Lu; else goto c2Lt;
      
      Generated Cmm sizes do not change too much, but binaries are very
      slightly larger, due to the fact that the new instructions are longer in
      encoded form. E.g. previously entry code for D8 above would be
      
          00000000000001c0 <Lib_D8_con_info>:
           1c0:	48 ff c3             	inc    %rbx
           1c3:	ff 65 00             	jmpq   *0x0(%rbp)
      
      With this patch
      
          00000000000001d0 <Lib_D8_con_info>:
           1d0:	48 83 c3 07          	add    $0x7,%rbx
           1d4:	ff 65 00             	jmpq   *0x0(%rbp)
      
      This is one byte longer.
      
      Secondly, reading info table directly and then switching is shorter
      
          _c1co:
                  movq -1(%rbx),%rax
                  movl -4(%rax),%eax
                  // Switch on info table tag
                  jmp *_n1d5(,%rax,8)
      
      than doing the same switch, and then for the tag 7 doing another switch:
      
          // When tag is 7
          _c1ct:
                  andq $-8,%rbx
                  movq (%rbx),%rax
                  movl -4(%rax),%eax
                  // Switch on info table tag
                  ...
      
      Some changes of binary sizes in actual programs:
      
      - In NoFib the worst case is 0.1% increase in benchmark "parser" (see
        NoFib results below). All programs get slightly larger.
      
      - Stage 2 compiler size does not change.
      
      - In "containers" (the library) size of all object files increases
        0.0005%. Size of the test program "bitqueue-properties" increases
        0.03%.
      
      nofib benchmarks kindly provided by Ömer (@osa1):
      
      NoFib Results
      =============
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs    Instrs     Reads    Writes
      --------------------------------------------------------------------------------
                   CS          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  CSD          +0.0%      0.0%      0.0%     +0.0%     +0.0%
                   FS          +0.0%      0.0%      0.0%     +0.0%      0.0%
                    S          +0.0%      0.0%     -0.0%      0.0%      0.0%
                   VS          +0.0%      0.0%     -0.0%     +0.0%     +0.0%
                  VSD          +0.0%      0.0%     -0.0%     +0.0%     -0.0%
                  VSM          +0.0%      0.0%      0.0%      0.0%      0.0%
                 anna          +0.0%      0.0%     +0.1%     -0.9%     -0.0%
                 ansi          +0.0%      0.0%     -0.0%     +0.0%     +0.0%
                 atom          +0.0%      0.0%      0.0%      0.0%      0.0%
               awards          +0.0%      0.0%     -0.0%     +0.0%      0.0%
               banner          +0.0%      0.0%     -0.0%     +0.0%      0.0%
           bernouilli          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
         binary-trees          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                boyer          +0.0%      0.0%     +0.0%      0.0%     -0.0%
               boyer2          +0.0%      0.0%     +0.0%      0.0%     -0.0%
                 bspt          +0.0%      0.0%     +0.0%     +0.0%      0.0%
            cacheprof          +0.0%      0.0%     +0.1%     -0.8%      0.0%
             calendar          +0.0%      0.0%     -0.0%     +0.0%     -0.0%
             cichelli          +0.0%      0.0%     +0.0%      0.0%      0.0%
              circsim          +0.0%      0.0%     -0.0%     -0.1%     -0.0%
             clausify          +0.0%      0.0%     +0.0%     +0.0%      0.0%
        comp_lab_zift          +0.0%      0.0%     +0.0%      0.0%     -0.0%
             compress          +0.0%      0.0%     +0.0%     +0.0%      0.0%
            compress2          +0.0%      0.0%      0.0%      0.0%      0.0%
          constraints          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
         cryptarithm1          +0.0%      0.0%     +0.0%      0.0%      0.0%
         cryptarithm2          +0.0%      0.0%     +0.0%     -0.0%      0.0%
                  cse          +0.0%      0.0%     +0.0%     +0.0%      0.0%
         digits-of-e1          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
         digits-of-e2          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
               dom-lt          +0.0%      0.0%     +0.0%     +0.0%      0.0%
                eliza          +0.0%      0.0%     -0.0%     +0.0%      0.0%
                event          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
          exact-reals          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               exp3_8          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
               expert          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
       fannkuch-redux          +0.0%      0.0%     +0.0%      0.0%      0.0%
                fasta          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  fem          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                  fft          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                 fft2          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
             fibheaps          +0.0%      0.0%     +0.0%     +0.0%      0.0%
                 fish          +0.0%      0.0%     +0.0%     +0.0%      0.0%
                fluid          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               fulsom          +0.0%      0.0%     +0.0%     -0.0%     +0.0%
               gamteb          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                  gcd          +0.0%      0.0%     +0.0%     +0.0%      0.0%
          gen_regexps          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
               genfft          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                   gg          +0.0%      0.0%      0.0%     -0.0%      0.0%
                 grep          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               hidden          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                  hpg          +0.0%      0.0%     +0.0%     -0.1%     -0.0%
                  ida          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                infer          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
              integer          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
            integrate          +0.0%      0.0%      0.0%     +0.0%      0.0%
         k-nucleotide          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                kahan          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
              knights          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
               lambda          +0.0%      0.0%     +1.2%     -6.1%     -0.0%
           last-piece          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                 lcss          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                 life          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                 lift          +0.0%      0.0%     +0.0%     +0.0%      0.0%
               linear          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
            listcompr          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
             listcopy          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
             maillist          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
               mandel          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
              mandel2          +0.0%      0.0%     +0.0%     +0.0%     -0.0%
                 mate          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
              minimax          +0.0%      0.0%     -0.0%     +0.0%     -0.0%
              mkhprog          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
           multiplier          +0.0%      0.0%      0.0%     +0.0%     -0.0%
               n-body          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
             nucleic2          +0.0%      0.0%     +0.0%     +0.0%     -0.0%
                 para          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
            paraffins          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               parser          +0.1%      0.0%     +0.4%     -1.7%     -0.0%
              parstof          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                  pic          +0.0%      0.0%     +0.0%      0.0%     -0.0%
             pidigits          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                power          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
               pretty          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               primes          +0.0%      0.0%     +0.0%      0.0%      0.0%
            primetest          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               prolog          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               puzzle          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
               queens          +0.0%      0.0%      0.0%     +0.0%     +0.0%
              reptile          +0.0%      0.0%     +0.0%     +0.0%      0.0%
      reverse-complem          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
              rewrite          +0.0%      0.0%     +0.0%      0.0%     -0.0%
                 rfib          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                  rsa          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                  scc          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                sched          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                  scs          +0.0%      0.0%     +0.0%     +0.0%      0.0%
               simple          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                solid          +0.0%      0.0%     +0.0%     +0.0%      0.0%
              sorting          +0.0%      0.0%     +0.0%     -0.0%      0.0%
        spectral-norm          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
               sphere          +0.0%      0.0%     +0.0%     -1.0%      0.0%
               symalg          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
                  tak          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
            transform          +0.0%      0.0%     +0.4%     -1.3%     +0.0%
             treejoin          +0.0%      0.0%     +0.0%     -0.0%      0.0%
            typecheck          +0.0%      0.0%     -0.0%     +0.0%      0.0%
              veritas          +0.0%      0.0%     +0.0%     -0.1%     +0.0%
                 wang          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
            wave4main          +0.0%      0.0%     +0.0%      0.0%     -0.0%
         wheel-sieve1          +0.0%      0.0%     +0.0%     +0.0%     +0.0%
         wheel-sieve2          +0.0%      0.0%     +0.0%     +0.0%      0.0%
                 x2n1          +0.0%      0.0%     +0.0%     +0.0%      0.0%
      --------------------------------------------------------------------------------
                  Min          +0.0%      0.0%     -0.0%     -6.1%     -0.0%
                  Max          +0.1%      0.0%     +1.2%     +0.0%     +0.0%
       Geometric Mean          +0.0%     -0.0%     +0.0%     -0.1%     -0.0%
      
      NoFib GC Results
      ================
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs    Instrs     Reads    Writes
      --------------------------------------------------------------------------------
              circsim          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
          constraints          +0.0%      0.0%     -0.0%      0.0%     -0.0%
             fibheaps          +0.0%      0.0%      0.0%     -0.0%     -0.0%
               fulsom          +0.0%      0.0%      0.0%     -0.6%     -0.0%
             gc_bench          +0.0%      0.0%      0.0%      0.0%     -0.0%
                 hash          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 lcss          +0.0%      0.0%      0.0%     -0.0%      0.0%
            mutstore1          +0.0%      0.0%      0.0%     -0.0%     -0.0%
            mutstore2          +0.0%      0.0%     +0.0%     -0.0%     -0.0%
                power          +0.0%      0.0%     -0.0%      0.0%     -0.0%
           spellcheck          +0.0%      0.0%     -0.0%     -0.0%     -0.0%
      --------------------------------------------------------------------------------
                  Min          +0.0%      0.0%     -0.0%     -0.6%     -0.0%
                  Max          +0.0%      0.0%     +0.0%      0.0%      0.0%
       Geometric Mean          +0.0%     +0.0%     +0.0%     -0.1%     +0.0%
      
      Fixes #14373
      
      These performance regressions appear to be a fluke in CI. See the
      discussion in !1742 for details.
      
      Metric Increase:
          T6048
          T12234
          T12425
          Naperian
          T12150
          T5837
          T13035
      9897e8c8
  16. 05 Dec, 2019 1 commit
    • Vladislav Zavialov's avatar
      Pretty-printing of the * kind · 3354c68e
      Vladislav Zavialov authored
      Before this patch, GHC always printed the * kind unparenthesized.
      
      This led to two issues:
      
      1. Sometimes GHC printed invalid or incorrect code.
         For example, GHC would print:  type F @*   x = x
               when it meant to print:  type F @(*) x = x
         In the former case, instead of a kind application we were getting a
         type operator (@*).
      
      2. Sometimes GHC printed kinds that were correct but hard to read.
         Should  Either * Int  be read as  Either (*) Int
                                    or as  (*) Either Int  ?
         This depends on whether -XStarIsType is enabled, but it would be
         easier if we didn't have to check for the flag when reading the code.
      
      We can solve both problems by assigning (*) a different precedence. Note
      that Haskell98 kinds are not affected:
      
        ((* -> *) -> *) -> *  does NOT become  (((*) -> (*)) -> (*)) -> (*)
      
      The parentheses are added when (*) is used in a function argument
      position:
      
         F * * *   becomes  F (*) (*) (*)
         F A * B   becomes  F A (*) B
         Proxy *   becomes  Proxy (*)
         a * -> *  becomes  a (*) -> *
      3354c68e
  17. 03 Dec, 2019 1 commit
  18. 02 Dec, 2019 1 commit
  19. 30 Nov, 2019 1 commit
  20. 28 Nov, 2019 2 commits
    • Vladislav Zavialov's avatar
      Factor out HsSCC/HsCoreAnn/HsTickPragma into HsPragE · 6985e0fc
      Vladislav Zavialov authored
      This is a refactoring with no user-visible changes (except for GHC API
      users). Consider the HsExpr constructors that correspond to user-written
      pragmas:
      
        HsSCC         representing  {-# SCC ... #-}
        HsCoreAnn     representing  {-# CORE ... #-}
        HsTickPragma  representing  {-# GENERATED ... #-}
      
      We can factor them out into a separate datatype, HsPragE. It makes the
      code a bit tidier, especially in the parser.
      
      Before this patch:
      
        hpc_annot :: { Located ( (([AddAnn],SourceText),(StringLiteral,(Int,Int),(Int,Int))),
                                 ((SourceText,SourceText),(SourceText,SourceText))
                               ) }
      
      After this patch:
      
        prag_hpc :: { Located ([AddAnn], HsPragE GhcPs) }
      6985e0fc
    • Brian Wignall's avatar
      3748ba3a
  21. 27 Nov, 2019 2 commits
    • Vladislav Zavialov's avatar
      Whitespace-sensitive bang patterns (#1087, #17162) · 8168b42a
      Vladislav Zavialov authored
      This patch implements a part of GHC Proposal #229 that covers five
      operators:
      
      * the bang operator (!)
      * the tilde operator (~)
      * the at operator (@)
      * the dollar operator ($)
      * the double dollar operator ($$)
      
      Based on surrounding whitespace, these operators are disambiguated into
      bang patterns, lazy patterns, strictness annotations, type
      applications, splices, and typed splices.
      
      This patch doesn't cover the (-) operator or the -Woperator-whitespace
      warning, which are left as future work.
      8168b42a
    • Sebastian Graf's avatar
      Make warnings for TH splices opt-in · 5a08f7d4
      Sebastian Graf authored
      In #17270 we have the pattern-match checker emit incorrect warnings. The
      reason for that behavior is ultimately an inconsistency in whether we
      treat TH splices as written by the user (`FromSource :: Origin`) or as
      generated code (`Generated`). This was first reported in #14838.
      
      The current solution is to TH splices as `Generated` by default and only
      treat them as `FromSource` when the user requests so
      (-fenable-th-splice-warnings). There are multiple reasons for opt-in
      rather than opt-out:
      
        * It's not clear that the user that compiles a splice is the author of the code
          that produces the warning. Think of the situation where she just splices in
          code from a third-party library that produces incomplete pattern matches.
          In this scenario, the user isn't even able to fix that warning.
        * Gathering information for producing the warnings (pattern-match check
          warnings in particular) is costly. There's no point in doing so if the user
          is not interested in those warnings.
      
      Fixes #17270, but not #14838, because the proper solution needs a GHC
      proposal extending the TH AST syntax.
      5a08f7d4
  22. 25 Nov, 2019 1 commit
  23. 20 Nov, 2019 1 commit
  24. 17 Nov, 2019 2 commits
  25. 13 Nov, 2019 2 commits
    • Ryan Scott's avatar
      Print name prefixly in the Outputable instance for StandaloneKindSig · 9a939a6c
      Ryan Scott authored
      Issue #17461 was occurring because the `Outputable` instance for
      standalone kind signatures was simply calling `ppr` on the name in
      the kind signature, which does not add parentheses to infix names.
      The solution is simple: use `pprPrefixOcc` instead.
      
      Fixes #17461.
      9a939a6c
    • Ben Gamari's avatar
      Ensure that coreView/tcView are able to inline · 2d4f9ad8
      Ben Gamari authored
      Previously an import cycle between Type and TyCoRep meant that several
      functions in TyCoRep ended up SOURCE import coreView. This is quite
      unfortunate as coreView is intended to be fused into a larger pattern
      match and not incur an extra call.
      
      Fix this with a bit of restructuring:
      
       * Move the functions in `TyCoRep` which depend upon things in `Type`
         into `Type`
       * Fold contents of `Kind` into `Type` and turn `Kind` into a simple
         wrapper re-exporting kind-ish things from `Type`
       * Clean up the redundant imports that popped up as a result
      
      Closes #17441.
      
      Metric Decrease:
          T4334
      2d4f9ad8