Commit Graph

51 Commits

Author SHA1 Message Date
Kadir Cetinkaya c3dcd2673e [clangd] Enable include insertion for static index
Summary:
This enables include insertion by adding canonical includes into
preambledata.

Reviewers: ioeric, ilya-biryukov

Subscribers: javed.absar, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D57508

llvm-svn: 353054
2019-02-04 16:19:57 +00:00
Haojian Wu aa3ed5a983 [clangd] NFC: fix clang-tidy warnings.
Most are about llvm code style violation (found via
readability-identifier-naming check).

llvm-svn: 352205
2019-01-25 15:14:03 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Ilya Biryukov f2001aa743 [clangd] Remove 'using namespace llvm' from .cpp files. NFC
The new guideline is to qualify with 'llvm::' explicitly both in
'.h' and '.cpp' files. This simplifies moving the code between
header and source files and is easier to keep consistent.

llvm-svn: 350531
2019-01-07 15:45:19 +00:00
Ilya Biryukov 22fa465a8c [clangd] clang-format everything. NFC
llvm-svn: 350303
2019-01-03 13:28:05 +00:00
Haojian Wu b618849e31 [clangd] Expose FileStatus to LSP.
Summary:
Add an LSP extension "textDocument/clangd.fileStatus" to emit file-status information.

Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D55363

llvm-svn: 349768
2018-12-20 15:39:12 +00:00
Haojian Wu e58e0903e2 [clangd] Avoid emitting Queued status when we are able to acquire the Barrier.
Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D55359

llvm-svn: 349032
2018-12-13 13:09:50 +00:00
Haojian Wu ec3d02013f [clangd] C++ API for emitting file status.
Introduce clangd C++ API to emit the current status of file.

llvm-svn: 348475
2018-12-06 09:41:04 +00:00
Ilya Biryukov 16cc195e8d [clangd] Cleanup: make the diags callback global in TUScheduler
Reviewers: sammccall

Reviewed By: sammccall

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D54760

llvm-svn: 347474
2018-11-22 17:27:08 +00:00
Ilya Biryukov c76394bc4b [clangd] Cleanup: make diagnostics callbacks from TUScheduler non-racy
Summary:
Previously, removeDoc followed by an addDoc to TUScheduler resulted in
racy diagnostic responses, i.e. the old dianostics could be delivered
to the client after the new ones by TUScheduler.

To workaround this, we tracked a version number in ClangdServer and
discarded stale diagnostics. After this commit, the TUScheduler will
stop delivering diagnostics for removed files and the workaround in
ClangdServer is not required anymore.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, jfb, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D54829

llvm-svn: 347468
2018-11-22 15:39:54 +00:00
Sam McCall a2b048bc4b [clangd] Respect task cancellation in TUScheduler.
Summary:
- Reads are never executed if canceled before ready-to run.
  In practice, we finalize cancelled reads eagerly and out-of-order.
- Cancelled reads don't prevent prior updates from being elided, as they don't
  actually depend on the result of the update.
- Updates are downgraded from WantDiagnostics::Yes to WantDiagnostics::Auto when
  cancelled, which allows them to be elided when all dependent reads are
  cancelled and there are subsequent writes. (e.g. when the queue is backed up
  with cancelled requests).

The queue operations aren't optimal (we scan the whole queue for cancelled
tasks every time the scheduler runs, and check cancellation twice in the end).
However I believe these costs are still trivial in practice (compared to any
AST operation) and the logic can be cleanly separated from the rest of the
scheduler.

Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D54746

llvm-svn: 347450
2018-11-22 10:22:16 +00:00
Sam McCall 6d4eb46d0c [clangd] workspace/symbol should be async, it reads from the index.
Summary:
To enable this, TUScheduler has to provide a way to run async tasks without
needing a preamble or AST!

Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, jfb, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D53644

llvm-svn: 345268
2018-10-25 14:19:14 +00:00
Sam McCall c008af6466 [clangd] Namespace style cleanup in cpp files. NFC.
Standardize on the most common namespace setup in our *.cpp files:
  using namespace llvm;
  namespace clang {
  namespace clangd {
  void foo(StringRef) { ... }
And remove redundant llvm:: qualifiers. (Except for cases like
make_unique where this causes problems with std:: and ADL).

This choice is pretty arbitrary, but some broad consistency is nice.
This is going to conflict with everything. Sorry :-/

Squash the other configurations:

A)
  using namespace llvm;
  using namespace clang;
  using namespace clangd;
  void clangd::foo(StringRef);
This is in some of the older files. (It prevents accidentally defining a
new function instead of one in the header file, for what that's worth).

B)
  namespace clang {
  namespace clangd {
  void foo(llvm::StringRef) { ... }
This is fine, but in practice the using directive often gets added over time.

C)
  namespace clang {
  namespace clangd {
  using namespace llvm; // inside the namespace
This was pretty common, but is a bit misleading: name lookup preferrs
clang::clangd::foo > clang::foo > llvm:: foo (no matter where the using
directive is).

llvm-svn: 344850
2018-10-20 15:30:37 +00:00
Sam McCall 2c30fbcac5 [clangd] Lay JSONRPCDispatcher to rest.
Summary:
Most of its functionality is moved into ClangdLSPServer.
The decoupling between JSONRPCDispatcher, ProtocolCallbacks, ClangdLSPServer
was never real, and only served to obfuscate.

Some previous implicit/magic stuff is now explicit:
 - the return type of LSP method calls are now in the signature
 - no more reply() that gets the ID using global context magic
 - arg tracing no longer relies on RequestArgs::stash context magic either

This is mostly refactoring, but some deliberate fixes while here:
 - LSP method params are now by const reference
 - notifications and calls are now distinct namespaces.
   (some tests had protocol errors and needed updating)
 - we now reply to calls we failed to decode
 - outgoing calls use distinct IDs
A few error codes and message IDs changed in unimportant ways (see tests).

Reviewers: ioeric

Subscribers: mgorny, ilya-biryukov, javed.absar, MaskRay, jkorous, arphaman, jfb, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D53387

llvm-svn: 344737
2018-10-18 12:32:04 +00:00
Kirill Bobyrev 4a5ff88fdb [clangd] NFC: Migrate to LLVM STLExtras API where possible
This patch improves readability by migrating `std::function(ForwardIt
start, ForwardIt end, ...)` to LLVM's STLExtras range-based equivalent
`llvm::function(RangeT &&Range, ...)`.

Similar change in Clang: D52576.

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D52650

llvm-svn: 343937
2018-10-07 14:49:41 +00:00
Fangrui Song 847bd33166 [clangd] Fix TUScheduler typos
llvm-svn: 342198
2018-09-14 00:56:11 +00:00
Sam McCall 046557bc03 [clangd] Some nitpicking around the new split (preamble/main) dynamic index
Summary:
- DynamicIndex doesn't implement ParsingCallbacks, to make its role clearer.
  ParsingCallbacks is a separate object owned by the receiving TUScheduler.
  (I tried to get rid of the "index-like-object that doesn't implement index"
  but it was too messy).
- Clarified(?) docs around DynamicIndex - fewer details up front, more details
  inside.
- Exposed dynamic index from ClangdServer for memory monitoring and more
  direct testing of its contents (actual tests not added here, wanted to get
  this out for review)
- Removed a redundant and sligthly confusing filename param in a callback

Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D51221

llvm-svn: 341325
2018-09-03 16:37:59 +00:00
Sam McCall e6ce8da025 [clangd] Run SignatureHelp using an up-to-date preamble, waiting if needed.
Summary:
After code completion inserts a header, running signature help using the old
preamble will usually fail. So we add support for consistent preamble reads.

Reviewers: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Differential Revision: https://reviews.llvm.org/D51438

llvm-svn: 341076
2018-08-30 15:07:34 +00:00
Ilya Biryukov c572dae405 [clangd] Add some trace::Spans. NFC
llvm-svn: 340815
2018-08-28 10:57:45 +00:00
Ilya Biryukov c5e44c1805 [clangd] Add callbacks on parsed AST in addition to parsed preambles
Summary:
Will be used for updating the dynamic index on updates to the open files.
Currently we collect only information coming from the preamble
AST. This has a bunch of limitations:
  - Dynamic index misses important information from the body of the
    file, e.g. locations of definitions.
  - XRefs cannot be collected at all, since we can only obtain full
    information for the current file (preamble is parsed with skipped
    function bodies, therefore not reliable).

This patch only adds the new callback, actually updates to the index
will be done in a follow-up patch.

Reviewers: hokein

Reviewed By: hokein

Subscribers: kadircet, javed.absar, ioeric, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D50847

llvm-svn: 340401
2018-08-22 11:39:16 +00:00
Haojian Wu 4c0c37df4c [clangd] Always use the latest preamble
Summary:
Fix an inconsistent behavior of using `LastBuiltPreamble`/`NewPreamble`
in TUScheduler (see the test for details), AST should always use
NewPreamble. This patch makes LastBuiltPreamble always point to
NewPreamble.

Preamble rarely fails to build, even there are errors in headers, so we
assume it would not cause performace issue for code completion.

Reviewers: ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: javed.absar, ioeric, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D50695

llvm-svn: 340001
2018-08-17 08:15:22 +00:00
Eric Liu e745eb33d9 [clangd] Try to fix buildbot after r339320.
http://lab.llvm.org:8011/builders/clang-cmake-armv8-quick/builds/5487

llvm-svn: 339322
2018-08-09 09:25:26 +00:00
Eric Liu f40819ea2d [clangd] Record the file being processed in a TUScheduler thread in context.
Summary:
This allows implementations like different symbol indexes to know what
the current active file is. For example, some customized index implementation
might decide to only return results for some files.

Reviewers: ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: javed.absar, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D50446

llvm-svn: 339320
2018-08-09 09:05:45 +00:00
Ilya Biryukov ec9bd36f2d [clangd] Do not build AST if no diagnostics were requested
Summary:
It can be removed from the cache before the first access anyway, so
building it can be a waste of time.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: javed.absar, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D49991

llvm-svn: 338378
2018-07-31 13:45:37 +00:00
Ilya Biryukov 442c283218 [clangd] Report diagnostics even if WantDiags::No AST was reused
Summary:
After r338256, clangd stopped reporting diagnostics if WantDiags::No request
is followed by a WantDiags::Yes request but the AST can be reused.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: javed.absar, MaskRay, jkorous, arphaman, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D50045

llvm-svn: 338361
2018-07-31 11:47:52 +00:00
Ilya Biryukov 24ec072e18 [clangd] Do not remove AST from cache if nothing changed
We were previously clearing the AST cache if the inputs and the
preamble were the same, which is not desired.

llvm-svn: 338256
2018-07-30 15:30:45 +00:00
Ilya Biryukov 4055d8c9fa [clangd] Fix a comment. NFC
llvm-svn: 338241
2018-07-30 11:46:25 +00:00
Ilya Biryukov 74f2655dc7 [clangd] Fix (most) naming warnings from clang-tidy. NFC
llvm-svn: 338021
2018-07-26 12:05:31 +00:00
Ilya Biryukov 1720113ace [clangd] Do not rebuild AST if inputs have not changed
Summary:
If the contents are the same, the update most likely comes from the
fact that compile commands were invalidated. In that case we want to
avoid rebuilds in case the compile commands are actually the same.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: simark, javed.absar, MaskRay, jkorous, arphaman, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D49783

llvm-svn: 338012
2018-07-26 09:21:07 +00:00
Sam McCall bed5885d9e [clangd] Upgrade logging facilities with levels and formatv.
Summary:
log() is split into four functions:
 - elog()/log()/vlog() have different severity levels, allowing filtering
 - dlog() is a lazy macro which uses LLVM_DEBUG - it logs to the logger, but
   conditionally based on -debug-only flag and is omitted in release builds

All logging functions use formatv-style format strings now, e.g:
  log("Could not resolve URI {0}: {1}", URI, Result.takeError());

Existing log sites have been split between elog/log/vlog by best guess.

This includes a workaround for passing Error to formatv that can be
simplified when D49170 or similar lands.

Subscribers: ilya-biryukov, javed.absar, ioeric, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D49008

llvm-svn: 336785
2018-07-11 10:35:11 +00:00
Ilya Biryukov 4a9312079a [clangd] Wait for first preamble before code completion
Summary:
To avoid doing extra work of processing headers in the preamble
mutilple times in parallel.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: javed.absar, ioeric, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D48940

llvm-svn: 336538
2018-07-09 10:45:33 +00:00
Benjamin Kramer c36c09fe8e [clangd] Replace UniqueFunction with llvm::unique_function.
One implementation of this ought to be enough for everyone.

llvm-svn: 336228
2018-07-03 20:59:33 +00:00
Ilya Biryukov ba7b824939 [clangd] Fix a data race in TUScheduler
By recomputing CompilerInvocation instead of copying it.
The problem was caused by the fact that copies of CompilerInvocation
store references to the shared state (DiagnosticOptions) when copied,
causing data races when two different copies are destroyed from
different threads.

llvm-svn: 335836
2018-06-28 11:04:45 +00:00
Ilya Biryukov 0da27c7c8a [clangd] Compute better estimates for memory usage of the AST
Also fix the return value of IdleASTs::getUsedBytes().
It was 'bool' instead of 'size_t' *facepalm*.

llvm-svn: 333758
2018-06-01 14:44:57 +00:00
Ilya Biryukov cd16e559d2 [clangd] Attempt the fix the buildbots after r333737
llvm-svn: 333742
2018-06-01 12:03:16 +00:00
Ilya Biryukov 823b056f58 [clangd] Keep only a limited number of idle ASTs in memory
Summary:
After this commit, clangd will only keep the last 3 accessed ASTs in
memory. Preambles for each of the opened files are still kept in
memory to make completion and AST rebuilds fast.

AST rebuilds are usually fast enough, but having the last ASTs in
memory still considerably improves latency of operations like
findDefinition and documeneHighlight, which are often sent multiple
times a second when moving around the code. So keeping some of the last
accessed ASTs in memory seems like a reasonable tradeoff.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: malaperle, arphaman, klimek, javed.absar, ioeric, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D47063

llvm-svn: 333737
2018-06-01 10:08:43 +00:00
Ilya Biryukov 6c5e99ed46 [clangd] Build index on preamble changes instead of the AST changes
Summary:
This is more efficient and avoids data races when reading files that
come from the preamble. The staleness can occur when reading a file
from disk that changed after the preamble was built. This can lead to
crashes, e.g. when parsing comments.

We do not to rely on symbols from the main file anyway, since any info
that those provide can always be taken from the AST.

Reviewers: ioeric, sammccall

Reviewed By: ioeric

Subscribers: malaperle, klimek, javed.absar, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D47272

llvm-svn: 333196
2018-05-24 15:50:15 +00:00
Ilya Biryukov f1f3d57eb2 [clangd] Don't expose vfs in TUScheduler::runWithPreamble.
Summary:
It was previously an easy way to concurrently access a mutable vfs,
which is a recipe for disaster.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: klimek, jkorous-apple, cfe-commits, ioeric

Differential Revision: https://reviews.llvm.org/D44463

llvm-svn: 327537
2018-03-14 17:46:52 +00:00
Ilya Biryukov 71028b83e7 [clangd] Revamp handling of diagnostics.
Summary:
The new implementation attaches notes to diagnostic message and shows
the original diagnostics in the message of the note.

Reviewers: hokein, ioeric, sammccall

Reviewed By: sammccall

Subscribers: klimek, mgorny, cfe-commits, jkorous-apple

Differential Revision: https://reviews.llvm.org/D44142

llvm-svn: 327282
2018-03-12 15:28:22 +00:00
Sam McCall d1e0deb271 [clangd] Debounce streams of updates.
Summary:
Don't actually start building ASTs for new revisions until either:
- 500ms have passed since the last revision, or
- we actually need the revision for something (or to unblock the queue)

In practice, this avoids the "first keystroke results in diagnostics" problem.
This is kind of awkward to test, and the test is pretty bad.
It can be observed nicely by capturing a trace, though.

Reviewers: hokein, ilya-biryukov

Subscribers: klimek, jkorous-apple, ioeric, cfe-commits

Differential Revision: https://reviews.llvm.org/D43648

llvm-svn: 326546
2018-03-02 08:56:37 +00:00
Sam McCall 091557d2a8 [clangd] BindWithForward -> Bind. NFC
llvm-svn: 325868
2018-02-23 07:54:17 +00:00
Simon Pilgrim cadaf755f3 Fix "not all control paths return a value" MSVC warning. NFCI.
llvm-svn: 325802
2018-02-22 16:12:27 +00:00
Sam McCall 568e17f1e6 [clangd] Allow embedders some control over when diagnostics are generated.
Summary:
Through the C++ API, we support for a given snapshot version:
 - Yes: make sure we generate diagnostics for exactly this version
 - Auto: generate eventually-consistent diagnostics for at least this version
 - No: don't generate diagnostics for this version
Eventually auto should be debounced for better UX.

Through LSP, we force diagnostics for initial load (bypassing future debouncing)
and all updates follow the "auto" policy.

This is complicated to implement under the CancellationFlag design, so
rewrote that part to just inspect the queue instead.

It turns out we never pass None to the diagnostics callback, so remove Optional
from the signature. The questionable behavior of not invoking the callback at
all if CppFile::rebuild fails is not changed.

Reviewers: ilya-biryukov

Subscribers: klimek, jkorous-apple, ioeric, cfe-commits

Differential Revision: https://reviews.llvm.org/D43518

llvm-svn: 325774
2018-02-22 13:11:12 +00:00
Sam McCall c901c5db78 [clangd] Tracing: name worker threads, and enforce naming scheduled async tasks
Summary:
This has a bit of a blast radius, but I think there's enough value in "forcing"
us to give names to these async tasks for debugging. Guessing about what
multithreaded code is doing is so unfun...

The "file" param attached to the tasks may seem to be redundant with the thread
names, but note that thread names are truncated to 15 chars on linux!
We'll be lucky to get the whole basename...

Reviewers: ilya-biryukov

Subscribers: klimek, jkorous-apple, ioeric, cfe-commits

Differential Revision: https://reviews.llvm.org/D43388

llvm-svn: 325480
2018-02-19 09:56:28 +00:00
Sam McCall 0bb24cd4fa [clangd] Stop exposing Futures from ClangdServer operations.
Summary:
LSP has asynchronous semantics, being able to block on an async operation
completing is unneccesary and leads to tighter coupling with the threading.

In practice only tests depend on this, so we add a general-purpose "block until
idle" function to the scheduler which will work for all operations.

To get this working, fix a latent condition-variable bug in ASTWorker, and make
AsyncTaskRunner const-correct.

Reviewers: ilya-biryukov

Subscribers: klimek, jkorous-apple, ioeric, cfe-commits

Differential Revision: https://reviews.llvm.org/D43127

llvm-svn: 324990
2018-02-13 08:59:23 +00:00
Ilya Biryukov 44ba9e0364 [clangd] Remove threading-related code from ClangdUnit.h
Reviewers: sammccall, hokein, ioeric

Reviewed By: sammccall

Subscribers: klimek, jkorous-apple, cfe-commits

Differential Revision: https://reviews.llvm.org/D43065

llvm-svn: 324725
2018-02-09 10:17:23 +00:00
Ilya Biryukov 7e5ee26d1a Resubmit "[clangd] The new threading implementation"
Initially submitted as r324356 and reverted in r324386.

This change additionally contains a fix to crashes of the buildbots.
The source of the crash was undefined behaviour caused by
std::future<> whose std::promise<> was destroyed without calling
set_value().

llvm-svn: 324575
2018-02-08 07:37:35 +00:00
Ilya Biryukov 3693f5941a Revert "[clangd] The new threading implementation" (r324356)
And the follow-up changes r324361 and r324363.
These changes seem to break two buildbots:
  - http://lab.llvm.org:8011/builders/clang-atom-d525-fedora-rel/builds/14091
  - http://lab.llvm.org:8011/builders/clang-x86_64-linux-selfhost-modules-2/builds/16001

We will need to investigate what went wrong and resubmit the changes
afterwards.

llvm-svn: 324386
2018-02-06 19:22:40 +00:00
Ilya Biryukov cce8883094 [clangd] The new threading implementation
Summary:
In the new threading model clangd creates one thread per file to manage
the AST and one thread to process each of the incoming requests.
The number of actively running threads is bounded by the semaphore to
avoid overloading the system.

Reviewers: sammccall

Reviewed By: sammccall

Subscribers: klimek, mgorny, jkorous-apple, ioeric, hintonda, cfe-commits

Differential Revision: https://reviews.llvm.org/D42573

llvm-svn: 324356
2018-02-06 15:53:42 +00:00
Sam McCall d1a7a37c22 [clangd] Pass Context implicitly using TLS.
Summary:
Instead of passing Context explicitly around, we now have a thread-local
Context object `Context::current()` which is an implicit argument to
every function.
Most manipulation of this should use the WithContextValue helper, which
augments the current Context to add a single KV pair, and restores the
old context on destruction.

Advantages are:
- less boilerplate in functions that just propagate contexts
- reading most code doesn't require understanding context at all, and
  using context as values in fewer places still
- fewer options to pass the "wrong" context when it changes within a
  scope (e.g. when using Span)
- contexts pass through interfaces we can't modify, such as VFS
- propagating contexts across threads was slightly tricky (e.g.
  copy vs move, no move-init in lambdas), and is now encapsulated in
  the threadpool

Disadvantages are all the usual TLS stuff - hidden magic, and
potential for higher memory usage on threads that don't use the
context. (In practice, it's just one pointer)

Reviewers: ilya-biryukov

Subscribers: klimek, jkorous-apple, ioeric, cfe-commits

Differential Revision: https://reviews.llvm.org/D42517

llvm-svn: 323872
2018-01-31 13:40:48 +00:00