Whether a binding is a DFunId or not has consequences for the `-fdicts-strict`
flag, essentially if we are doing demand analysis for a DFunId then `-fdicts-strict` does
not apply because the constraint solver can create recursive groups of dictionaries.

In #22549 this was fixed for the "normal" case, see
Note [Do not strictify the argument dictionaries of a dfun].
However the loop still existed if the DFunId was being specialised.

The problem was that the specialiser would specialise a DFunId and
turn it into a VanillaId and so the demand analyser didn't know to
apply special treatment to the binding anymore and the whole recursive
group was optimised to bottom.

The solution is to transfer over the DFunId-ness of the binding in the specialiser so
that the demand analyser knows not to apply the `-fstrict-dicts`.

Fixes #22549

... thus fixing #22549.

The details are in the refurbished and no longer dead
`Note [Do not strictify a DFun's parameter dictionaries]`.

There's a regression test in T22549.

Simon Peyton Jones authored 2 years ago and Matthew Pickering committed 2 years ago

This is an experimental patch, motivated by #22886, which
tries eta-expanding PAPs.

Let's see what effect that has.

Closes #23027.

Asm-shortcutting may produce relative references to symbols defined in
other compilation units. This is not something that MachO relocations
support (see #21972). For this reason we disable the optimisation on
Darwin. We do so without a warning since this flag is enabled by `-O2`.

Another way to address this issue would be to rather implement a
PLT-relocatable jump-table strategy. However, this would only benefit
Darwin and does not seem worth the effort.

Closes #21972.

(cherry picked from commit 8bed166b)

For reasons that aren't clear, we were previously not giving Capability
the same favorable alignment on Windows that we provided on other
platforms. Fix this.

(cherry picked from commit 05c5b14c)

Previously we failed to tell the C allocator that `Capability`s needed
to be aligned, resulting in #22965.

Fixes #22965.
Fixes #22975.

(cherry picked from commit 2cca72cd)

(cherry picked from commit eeb5bd56)

In #22965 we noticed that changes in the size of `Capability` can result
in unsound behavior due to the `align` pragma claiming an alignment
which we don't in practice observe. Avoid this by statically asserting
that the size is a multiple of the alignment.

(cherry picked from commit 485ccdda)

Simon Peyton Jones authored 2 years ago and Ben Gamari committed 2 years ago

As #22998 showed, we were floating an unlifted binding to top
level, which breaks a Core invariant.

The fix is easy, albeit a little bit conservative.  See
Note [Care with unlifted bindings] in GHC.Core.Opt.Specialise

(cherry picked from commit 7192ef91)

Simon Peyton Jones authored 2 years ago and Ben Gamari committed 2 years ago

As #23012 showed, GHC.Core.Opt.Simplify.Utils.prepareAlts was
using an OutType to construct an InAlt.  When shadowing is in play,
this is outright wrong.

See Note [Shadowing in prepareAlts].

(cherry picked from commit ece092d0)

Simon Peyton Jones authored 2 years ago and Ben Gamari committed 2 years ago

As #23024 showed, in GHC.Core.Opt.Specialise.specImports, we were
generating specialisations (a locally-define function) for imported
functions; and then generating specialisations for those
locally-defined functions.  The RULE for the latter should be
attached to the local Id, not put in the rules-for-imported-ids
set.

Fix is easy; similar to what happens in GHC.HsToCore.addExportFlagsAndRules

(cherry picked from commit 0c200ab7)

The code wasn't taking into account some kind of overlap.

cgrun070 has been extended to test the missing case.

(cherry picked from commit 8b77f9bf)

Cheng Shao authored 2 years ago and Ben Gamari committed 2 years ago

hs_cmpxchg64 must return a StgWord64, otherwise incorrect runtime
results of 64-bit MO_Cmpxchg will appear in 32-bit unregisterised
builds, which go unnoticed at compile-time due to C implicit casting
in .hc files.

(cherry picked from commit 9fa54572)

Sebastian Graf authored 2 years ago and Ben Gamari committed 2 years ago

This reverts the bits affecting fusion of `drop` and `dropWhile` of commit
0f7588b5 and keeps just the small refactoring
unifying `flipSeqTake` and `flipSeqScanl'` into `flipSeq`.

It also adds a new test for #23021 (which was the reason for reverting) as
well as adds a clarifying comment to T18964.

Fixes #23021, unfixes #18964.

Metric Increase:
    T18964
Metric Decrease:
    T18964

(cherry picked from commit a2a1a1c0)

Simon Peyton Jones authored 2 years ago and Ben Gamari committed 2 years ago

As #23018 showed, in mkRuntimeRepCo we need to account for coercions
between TYPE and COERCION.

See Note [mkRuntimeRepCo] in GHC.Core.Coercion.

(cherry picked from commit bb500e2a)

Simon Peyton Jones authored 2 years ago and Ben Gamari committed 2 years ago

The test for naughtiness in record selectors is surprisingly subtle.
See the revised Note [Naughty record selectors] in GHC.Tc.TyCl.Utils.

Fixes #23038.

(cherry picked from commit cf118e2f)

Luite Stegeman authored 2 years ago and Ben Gamari committed 2 years ago

GHC was accepting `foreign import javascript` declarations
on non-JavaScript platforms. This adds a check so that these
are only supported on an platform that supports the JavaScript
calling convention.

Fixes #22774

(cherry picked from commit 1d7c2e4c9d63a7b392024cfcde299849b8d667a8)

Matthew Pickering authored 2 years ago and Ben Gamari committed 2 years ago

These functions are

* recursive
* overloaded

So it's important to add an `INLINABLE` pragma to each so that they can be
specialised at the use site when the specific numeric type is known.
Adding these pragmas improves the LazyText replicate benchmark (see ghc/ghc#22886 (comment 481020))

https://github.com/haskell/core-libraries-committee/issues/129
(cherry picked from commit be0b7209)

Cheng Shao authored 2 years ago and Ben Gamari committed 2 years ago

The wasm NCG used to map CCCS to a wasm global, based on the
observation that CCCS is a transient register that's already handled
by thread state load/store logic, so it doesn't need to be backed by
the rCCCS field in the register table.

Unfortunately, this is wrong, since even when Cmm execution hasn't
yielded back to the scheduler, the Cmm code may call enterFunCCS,
which does use rCCCS.

This breaks cost centre profiling in a subtle way, resulting in
inaccurate stack traces in some test cases. The fix is simple though:
just remove the CCCS mapping.

(cherry picked from commit 2592ab69)

Alexis King authored 2 years ago and Ben Gamari committed 2 years ago

This commit also adds a new -Dk RTS option to the debug RTS to assist
debugging continuation captures. Currently, the printed information is
quite minimal, but more can be added in the future if it proves to be
useful when debugging future issues.

fixes #23001

(cherry picked from commit e5794ede9e2af208669438a7f72958aeecbec111)

In 81975ef3 we attempted to fix #20253
by adding logic to the bindist Makefile to regenerate the `settings`
file from information gleaned by the bindist `configure` script.
However, this fix had no effect as `lib/settings` is shipped in the
binary distribution (to allow in-place use of the binary distribution).
As `lib/settings` already existed and its rule declared no dependencies,
`make` would fail to use the added rule to regenerate it.

Fix this by explicitly declaring a dependency from `lib/settings` on
`mk/config.mk`.

Fixes #22982.

(cherry picked from commit f8876261)

sheaf authored 2 years ago and Ben Gamari committed 2 years ago

This patch updates the warning message introduced in commit
9fb4ca89 to specify an explicit
migration timeline: GHC will no longer support this constraint solving
mechanism starting from GHC 9.10.

Fixes #22912

(cherry picked from commit daee5602)

Matthew Pickering authored 2 years ago and Ben Gamari committed 2 years ago

The first argument is Int64# unconditionally, so we better produce
something of that type. This fixes a core lint error found in the ad
package.

Fixes #23019

(cherry picked from commit 3c9b89ad)

Fixes #22708

(cherry picked from commit 348181dd)

Commit 7566fd9d with the fix for #22798 was
incomplete as it failed to handle MULTILINE_COMMENT pseudo-instructions, and
didn't completly fix the compiler panics when compiling with `-fregs-graph`.

Fixes #23002

(cherry picked from commit 0ea260da)