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It turns out we were using two different sets of type variables when
reifying data family instances in Template Haskell. We were using the
tyvars quantifying over the instance itself for the LHS, but using the
tyvars quantifying over the data family instance constructor for the
RHS. This commit uses the instance tyvars for both the LHS and the RHS,
fixing #13618.

Test Plan: make test TEST=T13618

Reviewers: goldfire, austin, bgamari

Reviewed By: goldfire, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13618

Differential Revision: https://phabricator.haskell.org/D3505

Commit 2f9f1f86
(#13487) fixes #12104 as well. This adds a regression test for the
program reported in #12104 to keep it fixed.

Test Plan: make test TEST=T12104

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #12104

Differential Revision: https://phabricator.haskell.org/D3495

Reviewers: austin, dfeuer

Reviewed By: dfeuer

Subscribers: Phyx, rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3509

If we see f (g x), and f is strict, we want to be a bit more eager to
inline g, because it may well expose an eval (on x perhaps) that can
be eliminated or shared.

I saw this in nofib boyer2, function RewriteFuns.onewayunify1.  It
showed up as a consequence of the preceding patch that makes the
simplifier do less work (Trac #13379).  We had

   f d (g x)

where f was a class-op. Previously we simplified both d and
(g x) with a RuleArgCtxt (making g a bit more eager to inline).
But now we simplify only d that way, then fire the rule, and
only then simplify (g x).  Firing the rule produces a strict
funciion, so we want to make a strict function encourage
inlining a bit.

This patch nails a Bad Bug exposed in Trac #13379. Roughly,
a deeply-nested application like
   f (f (f ....) ) )
could make the simplifier go exponential -- without producing
an exponential-sized result!

The reason was that we
  - simplified a (big) function argument
  - then decided to inline the function
  - then preInilneUnconditionally the argument
  - and then re-simplified the big argument

And if the "big argument" itself had a similar structure
things could get very bad.

Once I'd understood, it was easy to fix:

* See Note Note [Avoiding exponential behaviour] for an overview

* The key change is that Simplify.simplLam now as a case for
  (isSimplified dup). This is what removes the perf bug.

* But I also made simplCast more parsimonious about simplifying,
  avoiding doing so when the coercion is Refl

* And similarly I now try to avoid simplifying arguments
  where possible before applying rules.
  See Note [Trying rewrite rules]

The latter two points tackle common cases, and in those cases make the
simplifier take fewer iterations.

CoreArity.etaExpand tried to deal with eta-expanding expressions
with join points.  For example
    let j x = e in \y. b

But it is hard to eta-expand this in the "no-crap" way described in
Note [No crap in eta-expanded code], becuase it would mean pushing
the "apply to y" into the join RHS, and changing its type. And the
join might be recursive, and it might have an unfolding.

Moreover in elaborate cases like this I don't think we need the
no-crap thing.  So for now I'm simplifying the code by generating
   \z. (let j x = e in \y. b) z

Let's see if that gives rise to any problems.
See Note [Eta expansion for join points]

Also bumps Cabal submodule due to version bound bump.

Test Plan: validate

Reviewers: bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3501

Namely `Num`, `Functor`, `Applicative`, `Monad`, `Semigroup` and
`Monoid` for `Data.Ord.Down` (#13097).

Reviewers: austin, hvr, bgamari, RyanGlScott

Reviewed By: bgamari, RyanGlScott

Subscribers: RyanGlScott, rwbarton, thomie

GHC Trac Issues: #13097

Differential Revision: https://phabricator.haskell.org/D3500

Reviewers: simonmar, austin

Reviewed By: simonmar

Subscribers: RyanGlScott, rwbarton, thomie

GHC Trac Issues: #10640, #13611

Differential Revision: https://phabricator.haskell.org/D3498

Previously, we were unconditionally pretty-printing all type variable
binders when pretty-printing closed type families (e.g., in the output
of `:info` in GHCi). This threw me for a loop, so let's guard this behind
the `-fprint-explicit-foralls` flag.

Test Plan: make test TEST=T13420

Reviewers: goldfire, austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13420

Differential Revision: https://phabricator.haskell.org/D3497

This imports @bgamari's sync script into the mirror script
and adds a backup url for packages.

The idea is that the URLs won't need updating when updating
the tarballs from now on.

It will first try haskell.org,
failing that it'll try repo.msys2.org

Test Plan: try new command `mk/get-win32-tarballs.sh sync`

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, bgamari

Differential Revision: https://phabricator.haskell.org/D3488

Provide PowerPC optimised implementations of callish prim ops.

MO_?_QuotRem
The generic implementation of quotient remainder prim ops uses
a division and a remainder operation. There is no remainder on
PowerPC and so we need to implement remainder "by hand" which
results in a duplication of the divide operation when using the
generic code.

Avoid this duplication by implementing the prim op in the native
code generator.

MO_U_Mul2
Use PowerPC's instructions for long multiplication.

Addition and subtraction
Use PowerPC add/subtract with carry/overflow instructions

MO_Clz and MO_Ctz
Use PowerPC's CNTLZ instruction and implement count trailing
zeros using count leading zeros

MO_QuotRem2
Implement an algorithm given by Henry Warren in "Hacker's Delight"
using PowerPC divide instruction. TODO: Use long division instructions
when available (POWER7 and later).

Test Plan: validate on AIX and 32-bit Linux

Reviewers: simonmar, erikd, hvr, austin, bgamari

Reviewed By: erikd, hvr, bgamari

Subscribers: trofi, kgardas, thomie

Differential Revision: https://phabricator.haskell.org/D2973

This replaces the --with-* configure flags with the usual autoconf
environment variables, as suggested by #13583.

Test Plan: Configure on various platforms

Reviewers: hvr, trofi, thomie, austin

Reviewed By: trofi

Subscribers: rwbarton, erikd

GHC Trac Issues: #13583

Differential Revision: https://phabricator.haskell.org/D3499

This commit didn't consider the fact that binary distributions on Windows must
have relative toolchain paths. This caused #13560.

This reverts commit 48385cb2 (except for a
helpful comment).

(cherry picked from commit 960589e89da3dbf60e88042d7e064ad4a98fb2ff)

Summary:
setProgramDynFlags invalidates the whole module graph, forcing
everything to be re-summarised (including preprocessing) on every
:reload.

Looks like this was a bad regression in 8.0, but we didn't notice
because there was no test for it.  Now there is!

Test Plan:
* validate
* new unit test

Reviewers: bgamari, triple, austin, niteria, erikd, jme

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3398

We do not need to keep an enrivonment around to implement letrec, as
long as we only do call-by-name. Instead, evaluate letrec by
substituting for all the variables with their RHS wrapped in the letrec
binding.

Since nothing adds to the enrivonment any more, there is no need for a
S_Var rule.

Differential Revision: https://phabricator.haskell.org/D3466

This is a follow-up to df679403
which missed `INSTALL_BINS`

this program should be rejected, but is not (and segfaults).

Previously rmtree's error callback would throw an exception, breaking
out of the retry loop.

Test Plan: Validate on Windows

Reviewers: Phyx, austin

Reviewed By: Phyx

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3492

Consider one-line module
    module B (v) where v = "hello"
in -fvia-C mode it generates code like
    static char gibberish_str[] = "hello";

It resides in data section (precious resource on ia64!).
The patch switches genrator to emit:
    static const char gibberish_str[] = "hello";

Other types if symbols that gained 'const' qualifier are:

- info tables (from haskell and CMM)
- static reference tables (from haskell and CMM)

Cleanups along the way:

- fixed info tables defined in .cmm to reside in .rodata
- split out closure declaration into 'IC_' / 'EC_'
- added label declaration (based on label type) right before
  each label definition (based on section type) so that C
  compiler could check if declaration and definition matches
  at definition site.
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

Test Plan: ran testsuite on unregisterised x86_64 compiler

Reviewers: simonmar, ezyang, austin, bgamari, erikd

Reviewed By: bgamari, erikd

Subscribers: rwbarton, thomie

GHC Trac Issues: #8996

Differential Revision: https://phabricator.haskell.org/D3481

This is a derivation of a patch from @jophish.

This is necessary due to `haskeline`'s `terminfo` flag being marked as
`Manual` as of 43d7fa106027fcd4ec7f443923a8dd5b8c169f9c.

Reviewers: jophish, bgamari, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie, jophish

Differential Revision: https://phabricator.haskell.org/D3493

Summary:
Commit b207b536 (#11714) happened to
fix #13603 as well. Let's add a regression test so that it stays fixed.

Test Plan: make test TEST=T13603

Reviewers: bgamari, austin, simonpj

Reviewed By: bgamari, simonpj

Subscribers: simonpj, rwbarton, thomie

GHC Trac Issues: #13603

Differential Revision: https://phabricator.haskell.org/D3489

Test Plan: Validate

Reviewers: austin

Subscribers: rwbarton, thomie

GHC Trac Issues: #13587

Differential Revision: https://phabricator.haskell.org/D3474

Reviewers: austin

Subscribers: rwbarton, thomie

GHC Trac Issues: #13591

Differential Revision: https://phabricator.haskell.org/D3470

By default GhcThreaded is set by
```
GhcThreaded = $(if $(findstring thr,$(GhcRTSWays)),YES,NO)
```
so it seems incorrect to try to build iserv with -threaded when
GhcThreaded is not set. This came up when I was building GHC with
some strange combination of flavours (debugged and profiled but not
threaded).

Test Plan: harbormaster

Reviewers: simonmar, austin, bgamari

Reviewed By: bgamari

Subscribers: thomie, snowleopard

Differential Revision: https://phabricator.haskell.org/D3429

The conclusion of #13555 was that a program which began to fail to
typecheck (starting in GHC 8.2) was never correct to begin with. Let's
document why this is the case with respect to `MonoLocalBinds`'
interaction with kind generalization. Also adds the reported program as
a `compile_fail` testcase.

Test Plan: make test TEST=T13555 # Also, read the docs

Reviewers: goldfire, simonpj, austin, bgamari

Reviewed By: goldfire, simonpj, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13555

Differential Revision: https://phabricator.haskell.org/D3472

Further cleanup of the linker, we'll add elf_compat.h for a more
complete set of relocations.

Also Util.h has been added as suggested in the code already.

Depends on D3444, D3445

Reviewers: bgamari, austin, erikd, simonmar

Reviewed By: simonmar

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3446

This diff introduces ElfTypes similar to provide the linker
code with a richer data structure, similar to the approach
taken for mach-o already.

Reviewers: bgamari, austin, erikd, simonmar

Reviewed By: simonmar

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3445

Reviewers: austin, erikd, simonmar

Reviewed By: erikd

Subscribers: rwbarton, thomie

Differential Revision: https://phabricator.haskell.org/D3486