1. 21 Feb, 2020 1 commit
    • Simon Peyton Jones's avatar
      Re-implement unsafe coercions in terms of unsafe equality proofs · 74ad75e8
      Simon Peyton Jones authored
      (Commit message written by Omer, most of the code is written by Simon
      and Richard)
      
      See Note [Implementing unsafeCoerce] for how unsafe equality proofs and
      the new unsafeCoerce# are implemented.
      
      New notes added:
      
      - [Checking for levity polymorphism] in CoreLint.hs
      - [Implementing unsafeCoerce] in base/Unsafe/Coerce.hs
      - [Patching magic definitions] in Desugar.hs
      - [Wiring in unsafeCoerce#] in Desugar.hs
      
      Only breaking change in this patch is unsafeCoerce# is not exported from
      GHC.Exts, instead of GHC.Prim.
      
      Fixes #17443
      Fixes #16893
      
      NoFib
      -----
      
      --------------------------------------------------------------------------------
              Program           Size    Allocs    Instrs     Reads    Writes
      --------------------------------------------------------------------------------
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                  CSD          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                   FS          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                    S          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                   VS          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  VSD          -0.1%      0.0%     -0.0%     -0.0%     -0.1%
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                 anna          -0.0%      0.0%     -0.0%     -0.0%     -0.0%
                 ansi          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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               boyer2          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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                event          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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               exp3_8          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               expert          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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                  fft          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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                  gcd          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
          gen_regexps          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               genfft          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                   gg          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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              integer          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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              minimax          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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               parser          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
              parstof          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  pic          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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      reverse-complem          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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                 rfib          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  rsa          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  scc          -0.1%      0.0%     -0.1%     -0.1%     -0.1%
                sched          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  scs          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               simple          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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              sorting          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
        spectral-norm          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               sphere          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
               symalg          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                  tak          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
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                 wang          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
            wave4main          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
         wheel-sieve1          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
         wheel-sieve2          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
                 x2n1          -0.1%      0.0%     -0.0%     -0.0%     -0.0%
      --------------------------------------------------------------------------------
                  Min          -0.1%      0.0%     -0.5%     -0.3%     -0.4%
                  Max          -0.0%      0.0%     +0.0%     +0.0%     +0.0%
       Geometric Mean          -0.1%     -0.0%     -0.0%     -0.0%     -0.0%
      
      Test changes
      ------------
      
      - break006 is marked as broken, see #17833
      - The compiler allocates less when building T14683 (an unsafeCoerce#-
        heavy happy-generated code) on 64-platforms. Allocates more on 32-bit
        platforms.
      - Rest of the increases are tiny amounts (still enough to pass the
        threshold) in micro-benchmarks. I briefly looked at each one in a
        profiling build: most of the increased allocations seem to be because
        of random changes in the generated code.
      
      Metric Decrease:
          T14683
      
      Metric Increase:
          T12150
          T12234
          T12425
          T13035
          T14683
          T5837
          T6048
      Co-Authored-By: Richard Eisenberg's avatarRichard Eisenberg <rae@cs.brynmawr.edu>
      Co-Authored-By: Ömer Sinan Ağacan's avatarÖmer Sinan Ağacan <omeragacan@gmail.com>
      74ad75e8
  2. 19 Feb, 2020 3 commits
  3. 14 Feb, 2020 1 commit
  4. 13 Feb, 2020 1 commit
  5. 12 Feb, 2020 3 commits
  6. 11 Feb, 2020 3 commits
  7. 09 Feb, 2020 1 commit
  8. 08 Feb, 2020 6 commits
  9. 05 Feb, 2020 2 commits
    • Ömer Sinan Ağacan's avatar
      Remove CafInfo-related code from STG lambda lift pass · 9c89a48d
      Ömer Sinan Ağacan authored
      After c846618a we don't have accurate CafInfos for Ids in the current
      module and we're free to introduce new CAFFY or non-CAFFY bindings or
      change CafInfos of existing binders; so no we no longer need to
      maintain CafInfos in Core or STG passes.
      9c89a48d
    • Sebastian Graf's avatar
      PmCheck: Record type constraints arising from existentials in `PmCoreCt`s · c90eca55
      Sebastian Graf authored
      In #17703 (a follow-up of !2192), we established that contrary to my
      belief, type constraints arising from existentials in code like
      
      ```hs
      data Ex where Ex :: a -> Ex
      f _ | let x = Ex @Int 15 = case x of Ex -> ...
      ```
      
      are in fact useful.
      
      This commit makes a number of refactorings and improvements to comments,
      but fundamentally changes `addCoreCt.core_expr` to record the type
      constraint `a ~ Int` in addition to `x ~ Ex @a y` and `y ~ 15`.
      
      Fixes #17703.
      c90eca55
  10. 01 Feb, 2020 1 commit
    • Simon Peyton Jones's avatar
      Fix scoping of TyCon binders in TcTyClsDecls · 913287a0
      Simon Peyton Jones authored
      This patch fixes #17566 by refactoring the way we decide the final
      identity of the tyvars in the TyCons of a possibly-recursive nest
      of type and class decls, possibly with associated types.
      
      It's all laid out in
        Note [Swizzling the tyvars before generaliseTcTyCon]
      
      Main changes:
      
      * We have to generalise each decl (with its associated types)
        all at once: TcTyClsDecls.generaliseTyClDecl
      
      * The main new work is done in TcTyClsDecls.swizzleTcTyConBndrs
      
      * The mysterious TcHsSyn.zonkRecTyVarBndrs dies altogether
      
      Other smaller things:
      
      * A little refactoring, moving bindTyClTyVars from tcTyClDecl1
        to tcDataDefn, tcSynRhs, etc.  Clearer, reduces the number of
        parameters
      
      * Reduce the amount of swizzling required.
        Specifically, bindExplicitTKBndrs_Q_Tv doesn't need
          to clone a new Name for the TyVarTv, and not
          cloning means that in the vasly common case,
          swizzleTyConBndrs is a no-op
      
        In detail:
          Rename newTyVarTyVar --> cloneTyVarTyVar
          Add newTyVarTyTyVar that doesn't clone
          Use the non-cloning newTyVarTyVar in
             bindExplicitTKBndrs_Q_Tv
             Rename newFlexiKindedTyVarTyVar
                 --> cloneFlexiKindedTyVarTyVar
      
      * Define new utility function and use it
           HsDecls.familyDeclName ::
              FamilyDecl (GhcPass p) -> IdP (GhcPass p)
      
      Updates haddock submodule.
      913287a0
  11. 31 Jan, 2020 3 commits
    • Andreas Klebinger's avatar
      A few optimizations in STG and Cmm parts: · 2a87a565
      Andreas Klebinger authored
      (Guided by the profiler output)
      
      - Add a few bang patterns, INLINABLE annotations, and a seqList in a few
        places in Cmm and STG parts.
      
      - Do not add external variables as dependencies in STG dependency
        analysis (GHC.Stg.DepAnal).
      2a87a565
    • 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
      --------------------------------------------------------------------------------
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                  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%
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                 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%
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                 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%
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             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%
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          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
  12. 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
  13. 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 ghc/ghc!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
  14. 20 Jan, 2020 1 commit
  15. 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
  16. 13 Jan, 2020 2 commits
  17. 08 Jan, 2020 1 commit
    • Ryan Scott's avatar
      Print Core type applications with no whitespace after @ (#17643) · 923a1272
      Ryan Scott authored
      This brings the pretty-printer for Core in line with how visible
      type applications are normally printed: namely, with no whitespace
      after the `@` character (i.e., `f @a` instead of `f @ a`). While I'm
      in town, I also give the same treatment to type abstractions (i.e.,
      `\(@a)` instead of `\(@ a)`) and coercion applications (i.e.,
      `f @~x` instead of `f @~ x`).
      
      Fixes #17643.
      923a1272