[Git][ghc/ghc][wip/t23702] 19 commits: Compute all emitted diagnostic codes

Finley McIlwaine (@FinleyMcIlwaine) gitlab at gitlab.haskell.org
Wed Aug 9 21:15:34 UTC 2023 


Finley McIlwaine pushed to branch wip/t23702 at Glasgow Haskell Compiler / GHC


Commits:
0ef1d8ae by sheaf at 2023-08-08T21:26:51-04:00
Compute all emitted diagnostic codes

This commit introduces in GHC.Types.Error.Codes the function

  constructorCodes :: forall diag. (...) => Map DiagnosticCode String

which computes a collection of all the diagnostic codes that correspond
to a particular type. In particular, we can compute the collection of
all diagnostic codes emitted by GHC using the invocation

  constructorCodes @GhcMessage

We then make use of this functionality in the new "codes" test which
checks consistency and coverage of GHC diagnostic codes.
It performs three checks:

  - check 1: all non-outdated GhcDiagnosticCode equations
    are statically used.
  - check 2: all outdated GhcDiagnosticCode equations
    are statically unused.
  - check 3: all statically used diagnostic codes are covered by
    the testsuite (modulo accepted exceptions).

- - - - -
4bc7b1e5 by Fraser Tweedale at 2023-08-08T21:27:32-04:00
numberToRangedRational: fix edge cases for exp ≈ (maxBound :: Int)

Currently a negative exponent less than `minBound :: Int` results in
Infinity, which is very surprising and obviously wrong.

```
λ> read "1e-9223372036854775808" :: Double
0.0
λ> read "1e-9223372036854775809" :: Double
Infinity
```

There is a further edge case where the exponent can overflow when
increased by the number of tens places in the integer part, or
underflow when decreased by the number of leading zeros in the
fractional part if the integer part is zero:

```
λ> read "10e9223372036854775807" :: Double
0.0
λ> read "0.01e-9223372036854775808" :: Double
Infinity
```

To resolve both of these issues, perform all arithmetic and
comparisons involving the exponent in type `Integer`.  This approach
also eliminates the need to explicitly check the exponent against
`maxBound :: Int` and `minBound :: Int`, because the allowed range
of the exponent (i.e. the result of `floatRange` for the target
floating point type) is certainly within those bounds.

This change implements CLC proposal 192:
https://github.com/haskell/core-libraries-committee/issues/192

- - - - -
6eab07b2 by Alan Zimmerman at 2023-08-08T21:28:10-04:00
EPA: Remove Location from WarningTxt source

This is not needed.

- - - - -
1a98d673 by Sebastian Graf at 2023-08-09T16:24:29-04:00
Cleanup a TODO introduced in 1f94e0f7

The change must have slipped through review of !4412

- - - - -
2274abc8 by Sebastian Graf at 2023-08-09T16:24:29-04:00
More explicit strictness in GHC.Real

- - - - -
ce8aa54c by Sebastian Graf at 2023-08-09T16:24:30-04:00
exprIsTrivial: Factor out shared implementation

The duplication between `exprIsTrivial` and `getIdFromTrivialExpr_maybe` has
been bugging me for a long time.

This patch introduces an inlinable worker function `trivial_expr_fold` acting
as the single, shared decision procedure of triviality. It "returns" a
Church-encoded `Maybe (Maybe Id)`, so when it is inlined, it fuses to similar
code as before.
(Better code, even, in the case of `getIdFromTrivialExpr` which presently
allocates a `Just` constructor that cancels away after this patch.)

- - - - -
d004a36d by Sebastian Graf at 2023-08-09T16:24:30-04:00
Simplify: Simplification of arguments in a single function

The Simplifier had a function `simplArg` that wasn't called in `rebuildCall`,
which seems to be the main way to simplify args. Hence I consolidated the code
path to call `simplArg`, too, renaming to `simplLazyArg`.

- - - - -
8c73505e by Sebastian Graf at 2023-08-09T16:24:30-04:00
Core.Ppr: Omit case binder for empty case alternatives

A minor improvement to pretty-printing

- - - - -
d8d993f1 by Sebastian Graf at 2023-08-09T16:24:30-04:00
Disable tests RepPolyWrappedVar2 and RepPolyUnsafeCoerce1 in JS backend

... because those coerce between incompatible/unknown PrimReps.

- - - - -
f06e87e4 by Sebastian Graf at 2023-08-09T16:24:30-04:00
Inlining literals into boring contexts is OK

- - - - -
4a6b7c87 by Sebastian Graf at 2023-08-09T16:24:30-04:00
Clarify floating of unsafeEqualityProofs (#23754)

- - - - -
b0f4752e by Sebastian Graf at 2023-08-09T16:24:30-04:00
Kill SetLevel.notWorthFloating.is_triv (#23270)

We have had it since b84ba676034, when it operated on annotated expressions.
Nowadays it operates on vanilla `CoreExpr` though, so we should just call
`exprIsTrivial`; thus handling empty cases and string literals correctly.

- - - - -
7e0c8b3b by Sebastian Graf at 2023-08-09T16:24:30-04:00
ANFise string literal arguments (#23270)

This instates the invariant that a trivial CoreExpr translates to an atomic
StgExpr. Nice.

Annoyingly, in -O0 we sometimes generate
```
foo = case "blah"# of sat { __DEFAULT -> unpackCString# sat }
```
which makes it a bit harder to spot that we can emit a standard
`stg_unpack_cstring` thunk.

Fixes #23270.

- - - - -
357f2738 by Sebastian Graf at 2023-08-09T16:24:30-04:00
Deactivate -fcatch-nonexhaustive-cases in ghc-bignum (#23345)

- - - - -
59202c80 by Sebastian Graf at 2023-08-09T16:24:30-04:00
CorePrep: Eliminate EmptyCase and unsafeEqualityProof in CoreToStg instead

We eliminate EmptyCase by way of `coreToStg (Case e _ _ []) = coreToStg e` now.
The main reason is that it plays far better in conjunction with eta expansion
(as we aim to do for arguments in CorePrep, #23083), because we can discard
any arguments, `(case e of {}) eta == case e of {}`, whereas in `(e |> co) eta`
it's impossible to discard the argument.

We do also give the same treatment to unsafeCoerce proofs and treat them as
trivial iff their RHS is trivial.

It is also both much simpler to describe than the previous mechanism of emitting
an unsafe coercion and simpler to implement, removing quite a bit of commentary
and `CorePrepProv`.

In the ghc/alloc perf test `LargeRecord`, we introduce an additional Simplifier
iteration due to #17910. E.g., FloatOut produces a binding
```
lvl_s6uK [Occ=Once1] :: GHC.Types.Int
[LclId]
lvl_s6uK = GHC.Types.I# 2#

lvl_s6uL [Occ=Once1] :: GHC.Types.Any
[LclId]
lvl_s6uL
  = case Unsafe.Coerce.unsafeEqualityProof ... of
    { Unsafe.Coerce.UnsafeRefl v2_i6tr -> lvl_s6uK `cast` (... v2_i6tr ...)
    }
```
That occurs once and hence is pre-inlined unconditionally in the next Simplifier
pass. It's non-trivial to find a way around that, but not really harmful
otherwise. Hence we accept a 1.2% increase on some architectures.

Metric Increase:
    LargeRecord

- - - - -
00d31188 by Sebastian Graf at 2023-08-09T16:24:30-04:00
CorePrep: Eta expand arguments (#23083)

Previously, we'd only eta expand let bindings and lambdas,
now we'll also eta expand arguments such as in T23083:
```hs
g f h = f (h `seq` (h $))
```
Unless `-fpedantic-bottoms` is set, we'll now transform to
```hs
g f h = f (\eta -> h eta)
```
in CorePrep.

See the new `Note [Eta expansion of arguments in CorePrep]` for the details.

We only do this optimisation with -O2 because we saw 2-3% ghc/alloc regressions
in T4801 and T5321FD.

Fixes #23083.

- - - - -
bf885d7a by Matthew Craven at 2023-08-09T16:25:07-04:00
Bump bytestring submodule to 0.11.5, again

Fixes #23789.

The bytestring commit used here is unreleased;
a release can be made when necessary.

- - - - -
ad6142e1 by Finley McIlwaine at 2023-08-09T15:15:25-06:00
Add -dipe-stats flag

This is useful for seeing which info tables have information.

- - - - -
119c1268 by Finley McIlwaine at 2023-08-09T15:15:25-06:00
Add -finfo-table-map-with-fallback -finfo-table-map-with-stack

The -fno-info-table-map-with-stack flag omits STACK info tables from the info
table map, and the -fno-info-table-map-with-fallback flag omits info tables
with defaulted source locations from the map. In a test on the Agda codebase
the build results were about 7% smaller when both of those types of tables
were omitted.

Adds a test that verifies that passing each combination of these flags
results in the correct output for -dipe-stats, which is disabled for the js
backend since profiling is not implemented.

This commit also refactors a lot of the logic around extracting info tables
from the Cmm results and building the info table map.

This commit also fixes some issues in the users guide rst source to fix
warnings that were noticed while debugging the documentation for these flags.

Fixes #23702

- - - - -


30 changed files:

- .gitlab-ci.yml
- compiler/GHC/Cmm.hs
- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/FVs.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/Arity.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Simplify/Iteration.hs
- compiler/GHC/Core/Opt/Simplify/Utils.hs
- compiler/GHC/Core/Ppr.hs
- compiler/GHC/Core/TyCo/FVs.hs
- compiler/GHC/Core/TyCo/Rep.hs
- compiler/GHC/Core/TyCo/Subst.hs
- compiler/GHC/Core/TyCo/Tidy.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Core/Unfold.hs
- compiler/GHC/Core/Utils.hs
- compiler/GHC/CoreToIface.hs
- compiler/GHC/CoreToStg.hs
- compiler/GHC/CoreToStg/Prep.hs
- compiler/GHC/Driver/Config/CoreToStg/Prep.hs
- compiler/GHC/Driver/Config/StgToCmm.hs
- compiler/GHC/Driver/DynFlags.hs
- compiler/GHC/Driver/Errors/Ppr.hs
- compiler/GHC/Driver/Flags.hs
- compiler/GHC/Driver/GenerateCgIPEStub.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/HsToCore/Errors/Ppr.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5d84c9cb8f3b34624fc1b795a9008f0101e72521...119c1268543f46f3a3d3e3a2e979a1aac5f1c035

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5d84c9cb8f3b34624fc1b795a9008f0101e72521...119c1268543f46f3a3d3e3a2e979a1aac5f1c035
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