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<h3>
Ben Gamari pushed to branch wip/T13253
at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4>
Commits:
</h4>
<ul>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/71006532abb88a53df7c7e0b3a5e2c8af99a48d1">71006532</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-06-30T07:10:42-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Reject nested foralls/contexts in instance types more consistently
GHC is very wishy-washy about rejecting instance declarations with
nested `forall`s or contexts that are surrounded by outermost
parentheses. This can even lead to some strange interactions with
`ScopedTypeVariables`, as demonstrated in #18240. This patch makes
GHC more consistently reject instance types with nested
`forall`s/contexts so as to prevent these strange interactions.
On the implementation side, this patch tweaks `splitLHsInstDeclTy`
and `getLHsInstDeclHead` to not look through parentheses, which can
be semantically significant. I've added a
`Note [No nested foralls or contexts in instance types]` in
`GHC.Hs.Type` to explain why. This also introduces a
`no_nested_foralls_contexts_err` function in `GHC.Rename.HsType` to
catch nested `forall`s/contexts in instance types. This function is
now used in `rnClsInstDecl` (for ordinary instance declarations) and
`rnSrcDerivDecl` (for standalone `deriving` declarations), the latter
of which fixes #18271.
On the documentation side, this adds a new
"Formal syntax for instance declaration types" section to the GHC
User's Guide that presents a BNF-style grammar for what is and isn't
allowed in instance types.
Fixes #18240. Fixes #18271.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/bccf3351a28638fba94953c4bb244ecfc3a1a044">bccf3351</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-06-30T07:10:46-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add ghc-bignum to 8.12 release notes
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/81704a6f3b155b0bfbc20f53cd821be3cb9006a7">81704a6f</a></strong>
<div>
<span>by David Eichmann</span>
<i>at 2020-06-30T07:10:48-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Update ssh keys in CI performance metrics upload script
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/85310fb83fdb7d7294bd453026102fc42000bf14">85310fb8</a></strong>
<div>
<span>by Joshua Price</span>
<i>at 2020-06-30T07:10:49-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add missing Ix instances for tuples of size 6 through 15 (#16643)
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/cbb6b62f54c77637e29bc66e3d1214541c347753">cbb6b62f</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-07-01T15:41:38-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Implement -XLexicalNegation (GHC Proposal #229)
This patch introduces a new extension, -XLexicalNegation, which detects
whether the minus sign stands for negation or subtraction using the
whitespace-based rules described in GHC Proposal #229.
Updates haddock submodule.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/fb5a0d01d575cdb830918a6a0406f385de2749c2">fb5a0d01</a></strong>
<div>
<span>by Martin Handley</span>
<i>at 2020-07-01T15:42:14-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">#17169: Clarify Fixed's Enum instance.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b316804dbafe1d0287fd33f656b7ce5711ec34f7">b316804d</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-01T15:42:49-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Improve debug tracing for substitution
This patch improves debug tracing a bit (#18395)
* Remove the ancient SDoc argument to substitution, replacing it
with a HasDebugCallStack constraint. The latter does the same
job (indicate the call site) but much better.
* Add HasDebugCallStack to simpleOptExpr, exprIsConApp_maybe
I needed this to help nail the lookupIdSubst panic in
#18326, #17784
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/5c9fabb82b39aed9e61c6b78c72312b20a568c68">5c9fabb8</a></strong>
<div>
<span>by Hécate</span>
<i>at 2020-07-01T15:43:25-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add most common return values for `os` and `arch`
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/76d8cc744977d98f6a427b1816198709e2d2e856">76d8cc74</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-07-01T15:44:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Desugar quoted uses of DerivingVia and expression type signatures properly
The way that `GHC.HsToCore.Quote` desugared quoted `via` types (e.g.,
`deriving via forall a. [a] instance Eq a => Eq (List a)`) and
explicit type annotations in signatures (e.g.,
`f = id @a :: forall a. a -> a`) was completely wrong, as it did not
implement the scoping guidelines laid out in
`Note [Scoped type variables in bindings]`. This is easily fixed.
While I was in town, I did some minor cleanup of related Notes:
* `Note [Scoped type variables in bindings]` and
`Note [Scoped type variables in class and instance declarations]`
say very nearly the same thing. I decided to just consolidate the
two Notes into `Note [Scoped type variables in quotes]`.
* `Note [Don't quantify implicit type variables in quotes]` is
somewhat outdated, as it predates GHC 8.10, where the
`forall`-or-nothing rule requires kind variables to be explicitly
quantified in the presence of an explicit `forall`. As a result,
the running example in that Note doesn't even compile. I have
changed the example to something simpler that illustrates the
same point that the original Note was making.
Fixes #18388.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/44d6a3352d708785b75aeb616bfc7efff839184e">44d6a335</a></strong>
<div>
<span>by Andreas Klebinger</span>
<i>at 2020-07-02T02:54:54-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">T16012: Be verbose on failure.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f985333002c1690bf49debcc64fc65ed1d1de244">f9853330</a></strong>
<div>
<span>by Ryan Scott</span>
<i>at 2020-07-02T02:55:29-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Bump ghc-prim version to 0.7.0
Fixes #18279. Bumps the `text` submodule.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/23e4e04700f840e3c4e75ccb2085aea05bfb5318">23e4e047</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-02T10:46:31-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Hadrian: fix PowerPC64le support (#17601)
[ci skip]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3cdd8d69f5c1d63137b9b56992bb9b74a6785459">3cdd8d69</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-02T10:47:08-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">NCG: correctly handle addresses with huge offsets (#15570)
Before this patch we could generate addresses of this form:
movzbl cP0_str+-9223372036854775808,%eax
The linker can't handle them because the offset is too large:
ld.lld: error: Main.o:(.text+0xB3): relocation R_X86_64_32S out of range: -9223372036852653050 is not in [-2147483648, 2147483647]
With this patch we detect those cases and generate:
movq $-9223372036854775808,%rax
addq $cP0_str,%rax
movzbl (%rax),%eax
I've also refactored `getAmode` a little bit to make it easier to
understand and to trace.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4d90b3ff02002ea25460d087dde56f69a9641096">4d90b3ff</a></strong>
<div>
<span>by Gabor Greif</span>
<i>at 2020-07-02T20:07:59-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">No need for CURSES_INCLUDE_DIRS
This is a leftover from ef63ff27251a20ff11e58c9303677fa31e609a88</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f08d6316d3d19b627550d99b4364e9bf0b45c329">f08d6316</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-02T20:08:36-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Replace Opt_SccProfilingOn flag with sccProfilingEnabled helper function
SCC profiling was enabled in a convoluted way: if WayProf was enabled,
Opt_SccProfilingOn general flag was set (in
`GHC.Driver.Ways.wayGeneralFlags`), and then this flag was queried in
various places.
There is no need to go via general flags, so this patch defines a
`sccProfilingEnabled :: DynFlags -> Bool` helper function that just
checks whether WayProf is enabled.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8cc7274b8de254c7266b61fadbc6795dc37bd1e9">8cc7274b</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-03T02:49:27-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/ProfHeap: Only allocate the Censuses that we need
When not LDV profiling there is no reason to allocate 32 Censuses; one
will do. This is a very small memory footprint optimisation, but it
comes for free.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b835112cbeaa6e34a8bae7b7697bdf2826edaa9a">b835112c</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-03T02:49:27-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts/ProfHeap: Free old allocations when reinitialising Censuses
Previously when not LDV profiling we would repeatedly reinitialise
`censuses[0]` with `initEra`. This failed to free the `Arena` and
`HashTable` from the old census, resulting in a memory leak.
Fixes #18348.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/34be6523a220b2be972b391d8ad26b75f7c26eb1">34be6523</a></strong>
<div>
<span>by Valery Tolstov</span>
<i>at 2020-07-03T02:50:03-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Mention flags that are not enabled by -Wall (#18372)
* Mention missing flags that are not actually enabled by -Wall (docs/users_guide/using-warnings.rst)
* Additionally remove -Wmissing-monadfail-instances from the list of flags enabled by -Wcompat, as it is not the case since 8.8
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/edc8d22b2eea5d43dd6c3d0e4b2f85fc02ffa5ce">edc8d22b</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-03T02:50:40-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">LLVM: support R9 and R10 registers
d535ef006d85dbdb7cda2b09c5bc35cb80108909 allowed the use of up to 10
vanilla registers but didn't update LLVM backend to support them. This
patch fixes it.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4bf18646acbb5a59ad8716aedc32acfe2ead0f58">4bf18646</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-03T08:37:42+01:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Improve handling of data type return kinds
Following a long conversation with Richard, this patch tidies up the
handling of return kinds for data/newtype declarations (vanilla,
family, and instance).
I have substantially edited the Notes in TyCl, so they would
bear careful reading.
Fixes #18300, #18357
In GHC.Tc.Instance.Family.newFamInst we were checking some Lint-like
properties with ASSSERT. Instead Richard and I have added
a proper linter for axioms, and called it from lintGblEnv, which in
turn is called in tcRnModuleTcRnM
New tests (T18300, T18357) cause an ASSERT failure in HEAD.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/41d2649288a5debcb4c8003e54b7d3072ab951c5">41d26492</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-03T17:33:59-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">DynFlags: avoid the use of sdocWithDynFlags in GHC.Core.Rules (#17957)
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7aa6ef110d8cc6626b1cf18d85a37cbac53e2795">7aa6ef11</a></strong>
<div>
<span>by Hécate</span>
<i>at 2020-07-03T17:34:36-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add the __GHC_FULL_VERSION__ CPP macro to expose the full GHC version
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e61d539527a7398017f759c67621ba18a15878f7">e61d5395</a></strong>
<div>
<span>by Chaitanya Koparkar</span>
<i>at 2020-07-07T13:55:59-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">ghc-prim: Turn some comments into haddocks
[ci skip]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/37743f91a3f5018a8894ca6d35e8b423e4e08b50">37743f91</a></strong>
<div>
<span>by John Ericson</span>
<i>at 2020-07-07T13:56:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Support `timesInt2#` in LLVM backend
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/46397e530e1b107c6b8932f7ca79ebab53a3249a">46397e53</a></strong>
<div>
<span>by John Ericson</span>
<i>at 2020-07-07T13:56:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">`genericIntMul2Op`: Call `genericWordMul2Op` directly
This unblocks a refactor, and removes partiality. It might be a PowerPC
regression but that should be fixable.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8a1c0584da40d0f8d1ffd01796efcce3b3d0820d">8a1c0584</a></strong>
<div>
<span>by John Ericson</span>
<i>at 2020-07-07T13:56:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Simplify `PrimopCmmEmit`
Follow @simonpj's suggestion of pushing the "into regs" logic into
`emitPrimOp`. With the previous commit getting rid of the recursion in
`genericIntMul2Op`, this is now an easy refactor.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6607f203fb9ad11af1463145810e1bd3c6c4f2c8">6607f203</a></strong>
<div>
<span>by John Ericson</span>
<i>at 2020-07-07T13:56:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">`opAllDone` -> `opIntoRegs`
The old name was and terrible and became worse after the previous
commit's refactor moved non-trivial funcationlity into its body.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/fdcc53babbd6c878344d2a3395bbd619428bd2dd">fdcc53ba</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-07T13:56:00-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Optimise genericIntMul2Op
We shouldn't directly call 'genericWordMul2Op' in genericIntMul2Op
because a target may provide a faster primop for 'WordMul2Op': we'd
better use it!
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/686e72253aed3880268dd6858eadd8c320f09e97">686e7225</a></strong>
<div>
<span>by Moritz Angermann</span>
<i>at 2020-07-07T13:56:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">[linker/rtsSymbols] More linker symbols
Mostly symbols needed for aarch64/armv7l
and in combination with musl, where we have
to rely on loading *all* objects/archives
- __stack_chk_* only when not DYNAMIC
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3f60b94de1f460ca3f689152860b108a19ce193e">3f60b94d</a></strong>
<div>
<span>by Moritz Angermann</span>
<i>at 2020-07-07T13:56:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">better if guards.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7abffced01f5680efafe44f6be2733eab321b039">7abffced</a></strong>
<div>
<span>by Moritz Angermann</span>
<i>at 2020-07-07T13:56:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix (1)
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/cdfeb3f24f76e8fd30452016676e56fbc827789a">cdfeb3f2</a></strong>
<div>
<span>by Moritz Angermann</span>
<i>at 2020-07-07T13:56:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">AArch32 symbols only on aarch32.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f496c9550098ffaa3bf25a3447c138626d79bae0">f496c955</a></strong>
<div>
<span>by Adam Sandberg Ericsson</span>
<i>at 2020-07-07T13:56:02-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">add -flink-rts flag to link the rts when linking a shared or static library #18072
By default we don't link the RTS when linking shared libraries because in the
most usual mode a shared library is an intermediary product, for example a
Haskell library, that will be linked into some executable in the end. So we
wish to defer the RTS flavour to link to the final link.
However sometimes the final product is the shared library, for example when
writing a plugin for some other system, so we do wish the shared library to
link the RTS.
For consistency we also make -staticlib honor this flag and its inversion.
-staticlib currently implies -flink-shared.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c59faf67fec83c98ffd1b65f1be0775b34f36595">c59faf67</a></strong>
<div>
<span>by Stefan Schulze Frielinghaus</span>
<i>at 2020-07-07T13:56:04-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">hadrian: link check-ppr against debugging RTS if ghcDebugged
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0effc57d48ace6b719a9f4cbeac67c95ad55010b">0effc57d</a></strong>
<div>
<span>by Adam Sandberg Ericsson</span>
<i>at 2020-07-07T13:56:05-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">rts linker: teach the linker about GLIBC's special handling of *stat, mknod and atexit functions #7072
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9615343363a68313c4bfdb068696002ecca7786e">96153433</a></strong>
<div>
<span>by Adam Sandberg Ericsson</span>
<i>at 2020-07-07T13:56:06-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">hadrian: make hadrian/ghci use the bootstrap compiler from configure #18190
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/4d24f886a428e95eb5e962294c77b12bffa40a52">4d24f886</a></strong>
<div>
<span>by Adam Sandberg Ericsson</span>
<i>at 2020-07-07T13:56:07-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">hadrian: ignore cabal configure verbosity related flags #18131
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7332bbffee9e2a712508540200eb52ed3d227426">7332bbff</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-07-07T13:56:08-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">testsuite: Widen T12234 acceptance window to 2%
Previously it wasn't uncommon to see +/-1% fluctuations in compiler
allocations on this test.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/180b63136f25d9fedb764cb9bc23637e7781ed4e">180b6313</a></strong>
<div>
<span>by Gabor Greif</span>
<i>at 2020-07-07T13:56:08-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">When running libtool, report it as such</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d3bd68978476487591fc60f7feb7cfb36b8fc3a3">d3bd6897</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-07T13:56:11-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">BigNum: rename BigNat types
Before this patch BigNat names were confusing because we had:
* GHC.Num.BigNat.BigNat: unlifted type used everywhere else
* GHC.Num.BigNat.BigNatW: lifted type only used to share static constants
* GHC.Natural.BigNat: lifted type only used for backward compatibility
After this patch we have:
* GHC.Num.BigNat.BigNat#: unlifted type
* GHC.Num.BigNat.BigNat: lifted type (reexported from GHC.Natural)
Thanks to @RyanGlScott for spotting this.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/929d26db3080ec49ab67690952a316fc082b479f">929d26db</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-07T13:56:12-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Bignum: don't build ghc-bignum with stage0
Noticed by @Ericson2314
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d25b6851bbd63b6a65fb7cd08b37c6bc74df9855">d25b6851</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-07T13:56:12-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Hadrian: ghc-gmp.h shouldn't be a compiler dependency
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0ddae2ba979ac2e01d7d9f6b79a9559fbfde46ea">0ddae2ba</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-07T13:56:14-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">DynFlags: factor out pprUnitId from "Outputable UnitId" instance
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/204f3f5ddec56403bfb12e74291b3b1d14824138">204f3f5d</a></strong>
<div>
<span>by Krzysztof Gogolewski</span>
<i>at 2020-07-07T13:56:18-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Remove unused function pprHsForAllExtra (#18423)
The function `pprHsForAllExtra` was called only on `Nothing`
since 2015 (1e041b7382b6aa).
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3033e0e4940e6ecc43f478f1dcfbd0c3cb1e3ef8">3033e0e4</a></strong>
<div>
<span>by Adam Sandberg Ericsson</span>
<i>at 2020-07-08T20:36:49-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">hadrian: add flag to skip rebuilding dependency information #17636
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b7de4b960a1024adcd0bded6bd320a90979d7ab8">b7de4b96</a></strong>
<div>
<span>by Stefan Schulze Frielinghaus</span>
<i>at 2020-07-09T09:49:22-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix GHCi :print on big-endian platforms
On big-endian platforms executing
import GHC.Exts
data Foo = Foo Float# deriving Show
foo = Foo 42.0#
foo
:print foo
results in an arithmetic overflow exception which is caused by function
index where moveBytes equals
word_size - (r + item_size_b) * 8
Here we have a mixture of units. Both, word_size and item_size_b have
unit bytes whereas r has unit bits. On 64-bit platforms moveBytes
equals then
8 - (0 + 4) * 8
which results in a negative and therefore invalid second parameter for a
shiftL operation.
In order to make things more clear the expression
(word .&. (mask `shiftL` moveBytes)) `shiftR` moveBytes
is equivalent to
(word `shiftR` moveBytes) .&. mask
On big-endian platforms the shift must be a left shift instead of a
right shift. For symmetry reasons not a mask is used but two shifts in
order to zero out bits. Thus the fixed version equals
case endian of
BigEndian -> (word `shiftL` moveBits) `shiftR` zeroOutBits `shiftL` zeroOutBits
LittleEndian -> (word `shiftR` moveBits) `shiftL` zeroOutBits `shiftR` zeroOutBits
Fixes #16548 and #14455
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3656dff8259199d0dab2d1a1f1b887c252a9c1a3">3656dff8</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-07-09T09:50:01-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">LLVM: fix MO_S_Mul2 support (#18434)
The value indicating if the carry is useful wasn't taken into account.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d9f095060b0f00d7140f8b0858b7a5dcbffea9ef">d9f09506</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-10T10:33:44-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Define multiShotIO and use it in mkSplitUniqueSupply
This patch is part of the ongoing eta-expansion saga;
see #18238.
It implements a neat trick (suggested by Sebastian Graf)
that allows the programmer to disable the default one-shot behaviour
of IO (the "state hack"). The trick is to use a new multiShotIO
function; see Note [multiShotIO]. For now, multiShotIO is defined
here in Unique.Supply; but it should ultimately be moved to the IO
library.
The change is necessary to get good code for GHC's unique supply;
see Note [Optimising the unique supply].
However it makes no difference to GHC as-is. Rather, it makes
a difference when a subsequent commit
Improve eta-expansion using ArityType
lands.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/bce695cc97cadbc3eced5b53efaaa0ecfd201d61">bce695cc</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-10T10:33:44-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Make arityType deal with join points
As Note [Eta-expansion and join points] describes,
this patch makes arityType deal correctly with join points.
What was there before was not wrong, but yielded lower
arities than it could.
Fixes #18328
In base GHC this makes no difference to nofib.
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
n-body -0.1% -0.1% -1.2% -1.1% 0.0%
--------------------------------------------------------------------------------
Min -0.1% -0.1% -55.0% -56.5% 0.0%
Max -0.0% 0.0% +16.1% +13.4% 0.0%
Geometric Mean -0.0% -0.0% -30.1% -31.0% -0.0%
But it starts to make real difference when we land the change to the
way mkDupableAlts handles StrictArg, in fixing #13253 and friends.
I think this is because we then get more non-inlined join points.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2b7c71cb79095a10b9a5964a5a0676a2a196e92d">2b7c71cb</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-11T12:17:02-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Improve eta-expansion using ArityType
As #18355 shows, we were failing to preserve one-shot info when
eta-expanding. It's rather easy to fix, by using ArityType more,
rather than just Arity.
This patch is important to suport the one-shot monad trick;
see #18202. But the extra tracking of one-shot-ness requires
the patch
Define multiShotIO and use it in mkSplitUniqueSupply
If that patch is missing, ths patch makes things worse in
GHC.Types.Uniq.Supply. With it, however, we see these improvements
T3064 compiler bytes allocated -2.2%
T3294 compiler bytes allocated -1.3%
T12707 compiler bytes allocated -1.3%
T13056 compiler bytes allocated -2.2%
Metric Decrease:
T3064
T3294
T12707
T13056
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/de139cc496c0e0110e252a1208ae346f47f8061e">de139cc4</a></strong>
<div>
<span>by Artem Pelenitsyn</span>
<i>at 2020-07-12T02:53:20-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">add reproducer for #15630
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c4de6a7a5c6433ae8c4df8a9fa09fbd9f3bbd0bf">c4de6a7a</a></strong>
<div>
<span>by Andreas Klebinger</span>
<i>at 2020-07-12T02:53:55-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Give Uniq[D]FM a phantom type for its key.
This fixes #17667 and should help to avoid such issues going forward.
The changes are mostly mechanical in nature. With two notable
exceptions.
* The register allocator.
The register allocator references registers by distinct uniques.
However they come from the types of VirtualReg, Reg or Unique in
various places. As a result we sometimes cast the key type of the
map and use functions which operate on the now typed map but take
a raw Unique as actual key. The logic itself has not changed it
just becomes obvious where we do so now.
* <Type>Env Modules.
As an example a ClassEnv is currently queried using the types `Class`,
`Name`, and `TyCon`. This is safe since for a distinct class value all
these expressions give the same unique.
getUnique cls
getUnique (classTyCon cls)
getUnique (className cls)
getUnique (tcName $ classTyCon cls)
This is for the most part contained within the modules defining the
interface. However it requires us to play dirty when we are given a
`Name` to lookup in a `UniqFM Class a` map. But again the logic did
not change and it's for the most part hidden behind the Env Module.
Some of these cases could be avoided by refactoring but this is left
for future work.
We also bump the haddock submodule as it uses UniqFM.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d2927dbcc2e97b47c8b2bc17683bf86face8e1af">d2927dbc</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-13T03:41:42-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Use dumpStyle when printing inlinings
This just makes debug-printing consistent,
and more informative.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c23021cf64ddc77812af1fdac088ae68659b6c0f">c23021cf</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-13T03:41:42-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Comments only
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/a5ca69c2ba72b5c08e66ac2ca55c6af35f4138e1">a5ca69c2</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-13T03:41:42-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Reduce result discount in conSize
Ticket #18282 showed that the result discount given by conSize
was massively too large. This patch reduces that discount to
a constant 10, which just balances the cost of the constructor
application itself.
Note [Constructor size and result discount] elaborates, as
does the ticket #18282.
Reducing result discount reduces inlining, which affects perf. I
found that I could increase the unfoldingUseThrehold from 80 to 90 in
compensation; in combination with the result discount change I get
these overall nofib numbers:
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
boyer -0.2% +5.4% -3.2% -3.4% 0.0%
cichelli -0.1% +5.9% -11.2% -11.7% 0.0%
compress2 -0.2% +9.6% -6.0% -6.8% 0.0%
cryptarithm2 -0.1% -3.9% -6.0% -5.7% 0.0%
gamteb -0.2% +2.6% -13.8% -14.4% 0.0%
genfft -0.1% -1.6% -29.5% -29.9% 0.0%
gg -0.0% -2.2% -17.2% -17.8% -20.0%
life -0.1% -2.2% -62.3% -63.4% 0.0%
mate +0.0% +1.4% -5.1% -5.1% -14.3%
parser -0.2% -2.1% +7.4% +6.7% 0.0%
primetest -0.2% -12.8% -14.3% -14.2% 0.0%
puzzle -0.2% +2.1% -10.0% -10.4% 0.0%
rsa -0.2% -11.7% -3.7% -3.8% 0.0%
simple -0.2% +2.8% -36.7% -38.3% -2.2%
wheel-sieve2 -0.1% -19.2% -48.8% -49.2% -42.9%
--------------------------------------------------------------------------------
Min -0.4% -19.2% -62.3% -63.4% -42.9%
Max +0.3% +9.6% +7.4% +11.0% +16.7%
Geometric Mean -0.1% -0.3% -17.6% -18.0% -0.7%
I'm ok with these numbers, remembering that this change removes
an *exponential* increase in code size in some in-the-wild cases.
I investigated compress2. The difference is entirely caused by this
function no longer inlining
WriteRoutines.$woutputCodes
= \ (w :: [CodeEvent]) ->
let result_s1Sr
= case WriteRoutines.outputCodes_$s$woutput w 0# 0# 8# 9# of
(# ww1, ww2 #) -> (ww1, ww2)
in (# case result_s1Sr of (x, _) ->
map @Int @Char WriteRoutines.outputCodes1 x
, case result_s1Sr of { (_, y) -> y } #)
It was right on the cusp before, driven by the excessive result
discount. Too bad!
Happily, the compiler/perf tests show a number of improvements:
T12227 compiler bytes-alloc -6.6%
T12545 compiler bytes-alloc -4.7%
T13056 compiler bytes-alloc -3.3%
T15263 runtime bytes-alloc -13.1%
T17499 runtime bytes-alloc -14.3%
T3294 compiler bytes-alloc -1.1%
T5030 compiler bytes-alloc -11.7%
T9872a compiler bytes-alloc -2.0%
T9872b compiler bytes-alloc -1.2%
T9872c compiler bytes-alloc -1.5%
Metric Decrease:
T12227
T12545
T13056
T15263
T17499
T3294
T5030
T9872a
T9872b
T9872c
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/818aba30cc10ea959afa405bd7c67e1b765239b7">818aba30</a></strong>
<div>
<span>by Simon Peyton Jones</span>
<i>at 2020-07-13T03:42:34-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">This patch addresses the exponential blow-up in the simplifier.
Specifically:
#13253 exponential inlining
#10421 ditto
#18140 strict constructors
#18282 another nested-function call case
This patch makes two significant changes:
1. For Ids that are used at most once in each branch of a case,
make the occurrence analyser record the total number of
syntactic occurrences. Then in postInlineUnconditionally
use that info to avoid inling something many many times.
Actual changes:
* See the occ_n_br field of OneOcc.
* postInlineUnconditionally
See Note [Suppress exponential blowup] in GHC.Core.Opt.Simplify.Utils
2. Change the way that mkDupableCont handles StrictArg.
The details are explained in GHC.Core.Opt.Simplify
Note [Duplicating StrictArg]
Current nofib run
Program Size Allocs Runtime Elapsed TotalMem
--------------------------------------------------------------------------------
VS -0.3% +115.9% +12.1% +11.2% 0.0%
boyer2 -0.3% +10.0% +3.5% +4.0% 0.0%
cryptarithm2 -0.3% +39.0% +16.6% +16.1% 0.0%
gamteb -0.3% +4.1% -0.0% +0.4% 0.0%
last-piece -0.3% +1.4% -1.1% -0.4% 0.0%
mate -0.4% -11.1% -8.5% -9.0% 0.0%
multiplier -0.3% -2.2% -1.5% -1.5% 0.0%
transform -0.3% +3.4% +0.5% +0.8% 0.0%
--------------------------------------------------------------------------------
Min -0.8% -11.1% -8.5% -9.0% 0.0%
Max -0.3% +115.9% +30.1% +26.4% 0.0%
Geometric Mean -0.3% +1.0% +1.0% +1.0% -0.0%
Should investigate these numbers.
But the tickets are indeed cured, I think.
</pre>
</li>
</ul>
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<li class="file-stats">
<a href="#7afeacc3c3f223aef50037f68cea140093ecc04a">
compiler/GHC/CmmToLlvm/Regs.hs
</a>
</li>
</ul>
<h5>The diff was not included because it is too large.</h5>
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