[Git][ghc/ghc][wip/dmdanal-precise-exn] 16 commits: Add outputable instances for the types in GHC.Iface.Ext.Types, add -ddump-hie

Sebastian Graf gitlab at gitlab.haskell.org
Mon Apr 6 19:13:13 UTC 2020



Sebastian Graf pushed to branch wip/dmdanal-precise-exn at Glasgow Haskell Compiler / GHC


Commits:
ef7576c4 by Zubin Duggal at 2020-04-03T06:24:56-04:00
Add outputable instances for the types in GHC.Iface.Ext.Types, add -ddump-hie
flag to dump pretty printed contents of the .hie file

Metric Increase:
   hie002

Because of the regression on i386:

compile_time/bytes allocated increased from i386-linux-deb9 baseline @ HEAD~10:
    Expected    hie002 (normal) compile_time/bytes allocated: 583014888.0 +/-10%
    Lower bound hie002 (normal) compile_time/bytes allocated:   524713399
    Upper bound hie002 (normal) compile_time/bytes allocated:   641316377
    Actual      hie002 (normal) compile_time/bytes allocated:   877986292
    Deviation   hie002 (normal) compile_time/bytes allocated:        50.6 %
*** unexpected stat test failure for hie002(normal)

- - - - -
9462452a by Andreas Klebinger at 2020-04-03T06:25:33-04:00
Improve and refactor StgToCmm codegen for DataCons.

We now differentiate three cases of constructor bindings:

1)Bindings which we can "replace" with a reference to
  an existing closure. Reference the replacement closure
  when accessing the binding.
2)Bindings which we can "replace" as above. But we still
  generate a closure which will be referenced by modules
  importing this binding.
3)For any other binding generate a closure. Then reference
  it.

Before this patch 1) did only apply to local bindings and we
didn't do 2) at all.

- - - - -
a214d214 by Moritz Bruder at 2020-04-03T06:26:11-04:00
Add singleton to NonEmpty in libraries/base

This adds a definition to construct a singleton non-empty list
(Data.List.NonEmpty) according to issue #17851.

- - - - -
f7597aa0 by Sylvain Henry at 2020-04-03T06:26:54-04:00
Testsuite: measure compiler stats for T16190

We were mistakenly measuring program stats

- - - - -
a485c3c4 by Sylvain Henry at 2020-04-03T06:26:54-04:00
Move blob handling into StgToCmm

Move handling of big literal strings from CmmToAsm to StgToCmm. It
avoids the use of `sdocWithDynFlags` (cf #10143). We might need to move
this handling even higher in the pipeline in the future (cf #17960):
this patch will make it easier.

- - - - -
cc2918a0 by Sylvain Henry at 2020-04-03T06:26:54-04:00
Refactor CmmStatics

In !2959 we noticed that there was some redundant code (in GHC.Cmm.Utils
and GHC.Cmm.StgToCmm.Utils) used to deal with `CmmStatics` datatype
(before SRT generation) and `RawCmmStatics` datatype (after SRT
generation).

This patch removes this redundant code by using a single GADT for
(Raw)CmmStatics.

- - - - -
9e60273d by Maxim Koltsov at 2020-04-03T06:27:32-04:00
Fix haddock formatting in Control.Monad.ST.Lazy.Imp.hs

- - - - -
1b7e8a94 by Andreas Klebinger at 2020-04-03T06:28:08-04:00
Turn newlines into spaces for hadrian/ghci.

The newlines break the command on windows.

- - - - -
4291bdda by Simon Peyton Jones at 2020-04-03T06:28:44-04:00
Major improvements to the specialiser

This patch is joint work of Alexis King and Simon PJ.  It does some
significant refactoring of the type-class specialiser.  Main highlights:

* We can specialise functions with types like
     f :: Eq a => a -> Ord b => b => blah
  where the classes aren't all at the front (#16473).  Here we can
  correctly specialise 'f' based on a call like
     f @Int @Bool dEqInt x dOrdBool
  This change really happened in an earlier patch
     commit 2d0cf6252957b8980d89481ecd0b79891da4b14b
     Author: Sandy Maguire <sandy at sandymaguire.me>
     Date:   Thu May 16 12:12:10 2019 -0400
  work that this new patch builds directly on that work, and refactors
  it a bit.

* We can specialise functions with implicit parameters (#17930)
     g :: (?foo :: Bool, Show a) => a -> String
  Previously we could not, but now they behave just like a non-class
  argument as in 'f' above.

* We can specialise under-saturated calls, where some (but not all of
  the dictionary arguments are provided (#17966).  For example, we can
  specialise the above 'f' based on a call
     map (f @Int dEqInt) xs
  even though we don't (and can't) give Ord dictionary.

  This may sound exotic, but #17966 is a program from the wild, and
  showed significant perf loss for functions like f, if you need
  saturation of all dictionaries.

* We fix a buglet in which a floated dictionary had a bogus demand
  (#17810), by using zapIdDemandInfo in the NonRec case of specBind.

* A tiny side benefit: we can drop dead arguments to specialised
  functions; see Note [Drop dead args from specialisations]

* Fixed a bug in deciding what dictionaries are "interesting"; see
  Note [Keep the old dictionaries interesting]

This is all achieved by by building on Sandy Macguire's work in
defining SpecArg, which mkCallUDs uses to describe the arguments of
the call. Main changes:

* Main work is in specHeader, which marched down the [InBndr] from the
  function definition and the [SpecArg] from the call site, together.

* specCalls no longer has an arity check; the entire mechanism now
  handles unders-saturated calls fine.

* mkCallUDs decides on an argument-by-argument basis whether to
  specialise a particular dictionary argument; this is new.
  See mk_spec_arg in mkCallUDs.

It looks as if there are many more lines of code, but I think that
all the extra lines are comments!

- - - - -
40a85563 by Ömer Sinan Ağacan at 2020-04-03T18:26:19+03:00
Revert accidental change in 9462452

[ci skip]

- - - - -
bd75e5da by Ryan Scott at 2020-04-04T07:07:58-04:00
Enable ImpredicativeTypes internally when typechecking selector bindings

This is necessary for certain record selectors with higher-rank
types, such as the examples in #18005. See
`Note [Impredicative record selectors]` in `TcTyDecls`.

Fixes #18005.

- - - - -
dcfe29c8 by Ömer Sinan Ağacan at 2020-04-06T13:16:08-04:00
Don't override proc CafInfos in ticky builds

Fixes #17947

When we have a ticky label for a proc, IdLabels for the ticky counter
and proc entry share the same Name. This caused overriding proc CafInfos
with the ticky CafInfos (i.e. NoCafRefs) during SRT analysis.

We now ignore the ticky labels when building SRTMaps. This makes sense
because:

- When building the current module they don't need to be in SRTMaps as
  they're initialized as non-CAFFY (see mkRednCountsLabel), so they
  don't take part in the dependency analysis and they're never added to
  SRTs.

  (Reminder: a "dependency" in the SRT analysis is a CAFFY dependency,
  non-CAFFY uses are not considered as dependencies for the algorithm)

- They don't appear in the interfaces as they're not exported, so it
  doesn't matter for cross-module concerns whether they're in the SRTMap
  or not.

See also the new Note [Ticky labels in SRT analysis].

- - - - -
cec2c71f by Simon Peyton Jones at 2020-04-06T13:16:44-04:00
Fix an tricky specialiser loop

Issue #17151 was a very tricky example of a bug in which the
specialiser accidentally constructs a recurive dictionary,
so that everything turns into bottom.

I have fixed variants of this bug at least twice before:
see Note [Avoiding loops].  It was a bit of a struggle
to isolate the problem, greatly aided by the work that
Alexey Kuleshevich did in distilling a test case.

Once I'd understood the problem, it was not difficult to fix,
though it did lead me a bit of refactoring in specImports.

- - - - -
e850d14f by Simon Peyton Jones at 2020-04-06T13:16:44-04:00
Refactoring only

This refactors DictBinds into a data type rather than a pair.
No change in behaviour, just better code

- - - - -
7ed49ad8 by Sebastian Graf at 2020-04-06T21:13:02+02:00
DmdAnal: Reflect precise exceptions in demand types

This is part two of the "fixing precise exception" plan in
https://gitlab.haskell.org/ghc/ghc/wikis/fixing-precise-exceptions
and, in combination with !2956, supercedes !2525.

In #13380 and #17676 we saw that we didn't preserve precise exception
semantics in demand analysis. We fixed that with minimal changes in
!2956, but that is terribly unprincipled.

That unprincipledness results in a loss of precision, which is tracked
by these new test cases:

- `T13380b`: Regression in dead code elimination, because !2956 was too
             syntactic about `raiseIO#`
- `T13380c`: No need to apply the "IO hack" when the IO action may not
             throw a precise exception
- `T13380d`: Demonstrating unsoundness of the "IO hack" when resorting
             to manual state token threading and direct use of primops.
             More details below.

The "IO hack" (which is a fallback to preserve precise exceptions
semantics and thus soundness, rather than some smart thing that
increases precision) is quite a misnomer and is called
`mayThrowPreciseException` now.

Also there is a slight chance that the IO hack was unsound before,
because it assumes that precise exceptions can only be thrown from a
case scrutinee of type `(# State# RealWorld, _ #)`.
I couldn't come up with a program using the `IO` abstraction that
violates this assumption. But it's easy to do so via manual state token
threading and direct use of primops, see `T13380d`. Also similar code
might be generated by Nested CPR in the (hopefully not too) distant
future.

Hence, we now have a more careful test in `forcesRealWorld` that passes
`T13380d`.

As for *how* we fixed these wrinkles: We augmented the `Divergence`
lattice to a diamond with two new elements forming the middle layer:

- `ExnOrDiv`: Means either `Diverges` (, throws an imprecise exception)
              or throws a *precise* exception.
- `ConOrDiv`: Means either `Diverges` (, throws an imprecise exception)
              or converges.

See the wiki page for more implementational details:
https://gitlab.haskell.org/ghc/ghc/wikis/fixing-precise-exceptions#replacing-hacks-by-principled-program-analyses

- - - - -
7e6b8aa2 by Sebastian Graf at 2020-04-06T21:13:02+02:00
Fix the perf regression

- - - - -


30 changed files:

- compiler/GHC.hs
- compiler/GHC/Cmm.hs
- compiler/GHC/Cmm/CLabel.hs
- compiler/GHC/Cmm/DebugBlock.hs
- compiler/GHC/Cmm/Info.hs
- compiler/GHC/Cmm/Info/Build.hs
- compiler/GHC/Cmm/Parser.y
- compiler/GHC/Cmm/Ppr/Decl.hs
- compiler/GHC/Cmm/Utils.hs
- compiler/GHC/CmmToAsm/PPC/CodeGen.hs
- compiler/GHC/CmmToAsm/PPC/Ppr.hs
- compiler/GHC/CmmToAsm/PPC/RegInfo.hs
- compiler/GHC/CmmToAsm/Ppr.hs
- compiler/GHC/CmmToAsm/SPARC/CodeGen.hs
- compiler/GHC/CmmToAsm/SPARC/CodeGen/Gen32.hs
- compiler/GHC/CmmToAsm/SPARC/Ppr.hs
- compiler/GHC/CmmToAsm/SPARC/ShortcutJump.hs
- compiler/GHC/CmmToAsm/X86/CodeGen.hs
- compiler/GHC/CmmToAsm/X86/Instr.hs
- compiler/GHC/CmmToAsm/X86/Ppr.hs
- compiler/GHC/CmmToC.hs
- compiler/GHC/CmmToLlvm.hs
- compiler/GHC/CmmToLlvm/Data.hs
- compiler/GHC/CmmToLlvm/Ppr.hs
- compiler/GHC/Core/Arity.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Op/CallArity.hs
- compiler/GHC/Core/Op/DmdAnal.hs
- compiler/GHC/Core/Op/FloatIn.hs
- compiler/GHC/Core/Op/FloatOut.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8ae14a25c07748b23f79dd67cfd01b8f814ff9da...7e6b8aa2cb9ec852229b3d3db9b40b7e8a9a0e2a

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8ae14a25c07748b23f79dd67cfd01b8f814ff9da...7e6b8aa2cb9ec852229b3d3db9b40b7e8a9a0e2a
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