Commit Graph

361064 Commits

Author SHA1 Message Date
Dan Liew 923cf890d1 Avoid failing a CHECK in `DlAddrSymbolizer::SymbolizePC`.
Summary:
It turns out the `CHECK(addr >= reinterpret_cast<upt>(info.dli_saddr)`
can fail because on armv7s on iOS 9.3 `dladdr()` returns
`info.dli_saddr` with an address larger than the address we provided.

We should avoid crashing here because crashing in the middle of reporting
an issue is very unhelpful. Instead we now try to compute a function offset
if the value we get back from `dladdr()` looks sane, otherwise we don't
set the function offset.

A test case is included. It's basically a slightly modified version of
the existing `test/sanitizer_common/TestCases/Darwin/symbolizer-function-offset-dladdr.cpp`
test case that doesn't run on iOS devices right now.

More details:

In the concrete scenario on armv7s `addr` is `0x2195c870` and the returned
`info.dli_saddr` is `0x2195c871`.

This what LLDB says when disassembling the code.

```
(lldb) dis -a 0x2195c870
libdyld.dylib`<redacted>:
    0x2195c870 <+0>: nop
    0x2195c872 <+2>: blx    0x2195c91c                ; symbol stub for: exit
    0x2195c876 <+6>: trap
```

The value returned by `dladdr()` doesn't make sense because it points
into the middle of a instruction.

There might also be other bugs lurking here because I noticed that the PCs we
gather during stackunwinding (before changing them with
`StackTrace::GetPreviousInstructionPc()`) look a little suspicious (e.g.  the
PC stored for the frame with fail to symbolicate is 0x2195c873) as they don't
look properly aligned. This probably warrants further investigation in the future.

rdar://problem/65621511

Reviewers: kubamracek, yln

Subscribers: kristof.beyls, llvm-commits, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D84262
2020-07-21 12:49:50 -07:00
Alexey Bataev 13bfe4b226 [OPENMP]Fix PR46012: declare target pointer cannot be accessed in target region.
Summary:
Need to avoid an optimization for base pointer mapping for target data
directives.

Reviewers: jdoerfert, ye-luo

Subscribers: yaxunl, guansong, cfe-commits, sstefan1, caomhin

Tags: #clang

Differential Revision: https://reviews.llvm.org/D84182
2020-07-21 15:48:32 -04:00
Fangrui Song 8a268bec1b Revert D82927 "[Loop Fusion] Integrate Loop Peeling into Loop Fusion"
This reverts commit bb8850d34d.

It broke 3 check-llvm-transforms-loopfusion tests in an ASAN build.

LoopFuse.cpp `for (BasicBlock *Pred : predecessors(BB)) {` may operate on a deleted BB.
2020-07-21 12:24:50 -07:00
David Green 1030e82598 [ARM] Add MVE_TwoOpPattern. NFC
This commons out a chunk of the different two operand MVE patterns into
a single helper multidef. Or technically two multidef patterns so that
the Dup qr patterns can also get the same treatment. This is most of the
two address instructions that we have some codegen pattern for (not ones
that we select purely from intrinsics). It does not include shifts,
which are more spread out and will need some extra work to be given the
same treatment.

Differential Revision: https://reviews.llvm.org/D83219
2020-07-21 19:51:37 +01:00
Jim Ingham 8d6aa688ee Remove the "bool" return from OptionValue::Clear and its subclasses.
Every override returns true and its return value is never checked.  I can't
see how clearing an OptionValue could fail, or what you would
do if it did.  The return serves no purpose.

Differential Revision: https://reviews.llvm.org/D84253
2020-07-21 11:32:55 -07:00
David Blaikie 63a45091e5 DebugInfo: make test/DebugInfo/X86/debug-macro-dwo.ll more comprehensive
The test doesn't really demonstrate the use of the debug_loc.dwo section
distinct from the debug_loc section for strings in debug_macro.dwo -
because there are no strings that appear uin debug_loc.dwo that weren't
already in debug_loc, so the indexes would remain the same even if the
section that was used was fixed (to use debug_loc.dwo as per spec).
2020-07-21 11:29:41 -07:00
Vedant Kumar 46334dfc3b [lldb/test] Skip test in TestBitfieldIvars.py instead of xfailing it
The test triggers an ASan exception, causing job failures on the
sanitizer bot.

As suggested by Shafik.
2020-07-21 11:29:09 -07:00
Aleksandr Platonov ff63d6be93 [clangd] Fixes in lit tests
Summary:
Changes:
- `background-index.test` Add Windows support.
- `did-change-configuration-params.test` Replace `cat | FileCheck` with `FileCheck --input-file`
- `test-uri-windows.test` This test did not run on Windows displite `REQUIRES: windows-gnu || windows-msvc` (replacement: `UNSUPPORTED: !(windows-gnu || windows-msvc)`).

Reviewers: sammccall, kadircet

Reviewed By: kadircet

Subscribers: njames93, ormris, ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83759
2020-07-21 21:21:40 +03:00
Guozhi Wei 28759e9fcc [MBP] Use profile count to compute tail dup cost if it is available
Current tail duplication in machine block placement pass uses block frequency
information in cost model. But frequency number has only relative meaning
compared to other basic blocks in the same function. A large frequency number
doesn't mean it is hot and a small frequency number doesn't mean it is cold.

To overcome this problem, this patch uses profile count in cost model if it's
available. So we can tail duplicate real hot basic blocks.

Differential Revision: https://reviews.llvm.org/D83265
2020-07-21 11:18:06 -07:00
Hiroshi Yamauchi 7bedae7dee [PGO][PGSO] Add profile guided size optimization to loop vectorization legality. 2020-07-21 11:16:36 -07:00
Marco Vanotti db00fac2a2 [compiler-rt][asan] decommit shadow memory for unmaps in fuchsia.
This CL allows asan allocator in fuchsia to decommit shadow memory
for memory allocated using mmap.

Big allocations in asan end up being allocated via `mmap` and freed with
`munmap`. However, when that memory is freed, asan returns the
corresponding shadow memory back to the OS via a call to
`ReleaseMemoryPagesToOs`.

In fuchsia, `ReleaseMemoryPagesToOs` is a no-op: to be able to free
memory back to the OS, you have to hold a handle to the vmo you want to
modify, which is tricky at the ReleaseMemoryPagesToOs level as that
function is not exclusively used for shadow memory.

The function `__sanitizer_fill_shadow` fills a given shadow memory range
with a specific value, and if that value is 0 (unpoison) and the memory
range is bigger than a threshold parameter, it will decommit that memory
if it is all zeroes.

This CL modifies the `FlushUnneededASanShadowMemory` function in
`asan_poisoning.cpp` to add a call to `__sanitizer_fill_shadow` with
value and threshold = 0. This way, all the unneeded shadow memory gets
returned back to the OS.

A test for this behavior can be found in fxrev.dev/391974

Differential Revision: https://reviews.llvm.org/D80355

Change-Id: Id6dd85693e78a222f0329d5b2201e0da753e01c0
2020-07-21 11:07:47 -07:00
Andy Soffer e5b3202b6f [libTooling] In Clang Transformer, change `Metadata` field to deferred evaluation.
`Metadata` is being changed from an `llvm::Any` to a `MatchConsumer<llvm::Any>`
so that it's evaluation can be be dependent on on `MatchResult`s passed in.

Reviewed By: ymandel, gribozavr2

Differential Revision: https://reviews.llvm.org/D83820
2020-07-21 18:05:49 +00:00
Serge Pavlov ac0edc5588 Revert "[Windows] Fix limit on command line size"
This reverts commit d4020ef7c4. It broke
LLDB buildbot: http://lab.llvm.org:8011/builders/lldb-x64-windows-ninja/builds/17702.
2020-07-22 01:00:32 +07:00
Jon Roelofs b9fc20ebe7 [compiler-rt][test][profile] Fix missing include
... on systems where wait() isn't one of the declarations transitively included
via unistd.h (i.e. Darwin).

Differential Revision: https://reviews.llvm.org/D84207
2020-07-21 11:59:27 -06:00
aartbik 19dbb230a2 [mlir] [VectorOps] Add scatter/gather operations to Vector dialect
Introduces the scatter/gather operations to the Vector dialect
(important memory operations for sparse computations), together
with a first reference implementation that lowers to the LLVM IR
dialect to enable running on CPU (and other targets that support
the corresponding LLVM IR intrinsics).

The operations can be used directly where applicable, or can be used
during progressively lowering to bring other memory operations closer to
hardware ISA support for a gather/scatter. The semantics of the operation
closely correspond to those of the corresponding llvm intrinsics.

Note that the operation allows for a dynamic index vector (which is
important for sparse computations). However, this first reference
lowering implementation "serializes" the address computation when
base + index_vector is converted to a vector of pointers. Exploring
how to use SIMD properly during these step is TBD. More general
memrefs and idiomatic versions of striding are also TBD.

Reviewed By: arpith-jacob

Differential Revision: https://reviews.llvm.org/D84039
2020-07-21 10:57:40 -07:00
Stefan Pintilie 0d3a5d09e3 [NFC][PowerPC] Updated a number of Power PC tests used for PC Relative
Updated the tests to use -mcpu=pwr10 instead of -mcpu=future.
Updated the tests to include Big Endian testing.
2020-07-21 12:28:56 -05:00
Fangrui Song aa830e9768 [LLVMgold.so][test] Fix tests after D84132/55fa315b0352 2020-07-21 10:18:32 -07:00
Jonas Devlieghere dd064afe84 [lldb] Add missing member initialziation list
My previous commit added the default arguments but didn't use them in
the member initialization list...
2020-07-21 10:15:38 -07:00
Raphael Isemann e031eda08d Revert "[lldb] Unify type name matching in FormattersContainer"
This reverts commit 5b0de5756c.

Apparently that caused some test to get stuck on Linuxx. Reverting for now.
2020-07-21 19:03:33 +02:00
Nico Weber 4fe912f186 Build: Move TF source file inclusion from build system to source files
Outside of compiler-rt (where it's arguably an anti-pattern too),
LLVM tries to keep its build files as simple as possible. See e.g.
llvm/docs/SupportLibrary.rst, "Code Organization".

Differential Revision: https://reviews.llvm.org/D84243
2020-07-21 13:02:34 -04:00
Kevin P. Neal 2d27f24b5a [NFC] Make documentation for CallBase::hasFnAttr() more clear. 2020-07-21 12:59:24 -04:00
Arthur Eubanks b13b858182 [NewPM] Support optnone under new pass manager
OptNoneInstrumentation is part of StandardInstrumentations. It skips
functions (or loops) that are marked optnone.

The feature of skipping optional passes for optnone functions under NPM
is gated on a -enable-npm-optnone flag. Currently it is by default
false. That is because we still need to mark all required passes to be
required. Otherwise optnone functions will start having incorrect
semantics.  After that is done in following changes, we can remove the
flag and always enable this.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D83519
2020-07-21 09:53:43 -07:00
Jonas Devlieghere 98efa3d57f [lldb] Change the CommandArgumentData ctor (NFC)
By using default arguments the caller can specify a subset without the
need for overloads. This is particularly useful in combination with
emplace_back as these objects are generally stored in a vector.
2020-07-21 09:50:30 -07:00
Raphael Isemann 5b0de5756c [lldb] Unify type name matching in FormattersContainer
Summary:

FormattersContainer stores LLDB's formatters. It's implemented as a templated
map-like data structures that supports any kind of value type and only allows
ConstString and RegularExpression as the key types. The keys are used for
matching type names (e.g., the ConstString key `std::vector` matches the type
with the same name while RegularExpression keys match any type where the
RegularExpression instance matches).

The fact that a single FormattersContainer can only match either by string
comparison or regex matching (depending on the KeyType) causes us to always have
two FormatterContainer instances in all the formatting code. This also leads to
us having every type name matching logic in LLDB twice. For example,
TypeCategory has to implement every method twice (one string matching one, one
regex matching one).

This patch changes FormattersContainer to instead have a single `TypeMatcher`
key that wraps the logic for string-based and regex-based type matching and is
now the only possible KeyType for the FormattersContainer. This means that a
single FormattersContainer can now match types with both regex and string
comparison.

To summarize the changes in this patch:
* Remove all the `*_Impl` methods from `FormattersContainer`
* Instead call the FormatMap functions from `FormattersContainer` with a
  `TypeMatcher` type that does the respective matching.
* Replace `ConstString` with `TypeMatcher` in the few places that directly
  interact with `FormattersContainer`.

I'm working on some follow up patches that I split up because they deserve their
own review:

* Unify FormatMap and FormattersContainer (they are nearly identical now).
* Delete the duplicated half of all the type matching code that can now use one
  interface.
* Propagate TypeMatcher through all the formatter code interfaces instead of
  always offering two functions for everything.

There is one ugly design part that I couldn't get rid of yet and that is that we
have to support getting back the string used to construct a `TypeMatcher` later
on. The reason for this is that LLDB only supports referencing existing type
matchers by just typing their respective input string again (without even
supplying if it's a regex or not).

Reviewers: davide, mib

Reviewed By: mib

Subscribers: mgorny, JDevlieghere

Differential Revision: https://reviews.llvm.org/D84151
2020-07-21 18:44:50 +02:00
Jordan Rupprecht 1ee1da1ea5 [NFC] Fix unused var warning 2020-07-21 09:26:01 -07:00
Jonas Devlieghere 1c9cc094d0 [lldb] Fix typo that went unnoticed on my case insensitive FS 2020-07-21 09:13:26 -07:00
Logan Smith fa42b7cf29 [clang-tools-extra] Disable -Wsuggest-override for unittests/
This avoids massive warning spam due to the unit tests' use of gtest and gmock, which do not use the 'override' keyword in their sources.

Differential Revision: https://reviews.llvm.org/D84213
2020-07-21 09:11:53 -07:00
Diego Caballero f8b72fba86 [MLIR][EDSC] Add fptrunc and fpext to EDSC
Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D84216
2020-07-21 08:55:18 -07:00
Jonas Devlieghere 9f8d481d68 [lldb/Reproducers] Don't recursively record everything in the CWD
RecordInterestingDirectory was added to collect dSYM bundles and their
content. For the current working directory we only want the directory to
be part of the VFS, not necessarily its contents. This patch renames the
current method to RecordInterestingDirectoryRecursively and adds a new
one that's not recursive.
2020-07-21 09:02:38 -07:00
Sidharth Baveja bb8850d34d [Loop Fusion] Integrate Loop Peeling into Loop Fusion
Summary:
This patch adds the ability to peel off iterations of the first loop in loop
fusion. This can allow for both loops to have the same trip count, making it
legal for them to be fused together.

Here is a simple scenario peeling can be used in loop fusion:

for (i = 0; i < 10; ++i)
  a[i] = a[i] + 3;
for (j = 1; j < 10; ++j)
  b[j] = b[j] + 5;

Here is we can make use of peeling, and then fuse the two loops together. We can
peel off the 0th iteration of the loop i, and then combine loop i and j for
i = 1 to 10.

a[0] = a[0] +3;
for (i = 1; i < 10; ++i) {
  a[i] = a[i] + 3;
  b[i] = b[i] + 5;
}

Currently peeling with loop fusion is only supported for loops with constant
trip counts and a single exit point. Both unguarded and guarded loops are
supported.

Author: sidbav (Sidharth Baveja)

Reviewers: kbarton, Meinersbur, bkramer, Whitney, skatkov, ashlykov, fhahn, bmahjour

Reviewed By: bmahjour

Subscribers: bmahjour, mgorny, hiraditya, zzheng

Tags: LLVM

Differential Revision: https://reviews.llvm.org/D82927
2020-07-21 15:59:14 +00:00
Chris Gyurgyik a16129c138
[libc] [Obvious] Fix typo.
Fixes typo for strstr in entrypoints.
str -> src.
2020-07-21 11:52:12 -04:00
Fangrui Song 86ab98b001 [ELF] -r: rewrite SHT_GROUP content if some members are combined or discarded
* If two group members are combined, we should leave just one index in the SHT_GROUP content.
* If a group member is discarded (/DISCARD/ or upcoming -r --gc-sections combination),
  we should drop its index in the SHT_GROUP content. LLD currently crashes (`getOutputSection()` is null).

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D84129
2020-07-21 08:49:45 -07:00
cgyurgyik d080635bfc [libc] Add strstr implementation.
Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D83956
2020-07-21 11:39:23 -04:00
Vince Bridgers 2015741086 [ASTImporter] Refactor ASTImporter to support custom downstream tests
Summary:
The purpose of this change is to do a small refactoring of code in
ASTImporterTest.cpp by moving it to ASTImporterFixtures.h in order to
support tests of downstream custom types and minimize the "living
downstream burden" of frequent integrations from community to a
downstream repo that implements custom AST import tests.

Reviewers: martong, a.sidorin, shafik

Reviewed By: martong

Subscribers: balazske, dkrupp, bjope, rnkovacs, teemperor, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83970
2020-07-21 10:34:17 -05:00
Fangrui Song 8c6d48baf6 [llvm-readobj] Construct relocation-aware DWARFDataExtractor to decode .eh_frame addresses correctly
In an object file, a "PC Begin" field in a FDE is usually relocated by a
PC-relative relocation. Use a relocation-aware DWARFDataExtractor overload (with
DWARFContext and a reference to its internal .eh_frame representation) to decode
addresses correctly. In an object file, most sections have addresses of zero. So
the displayed addresses are almost always offsets relative to the start of the
associated text section.

DWARFContext::create handles .eh_frame and .rela.eh_frame by itself, so if there
are more than one .eh_frame (technically possible, but almost always erronerous
in practice), this will only handle the first one.  Supporting multiple
.eh_frame is beyond the scope of this patch.

Reviewed By: grimar, jhenderson

Differential Revision: https://reviews.llvm.org/D84106
2020-07-21 08:33:19 -07:00
Saiyedul Islam 741e55aeed [OpenMP] Temporarily disable failing runtime tests for clang-12
Following tests were disabled for clang-11 after upgrading to
version 5.0 in D82963:

1. openmp/runtime/test/env/kmp_set_dispatch_buf.c
2. openmp/runtime/test/worksharing/for/kmp_set_dispatch_buf.c

They are also failing for clang-12. Thus this temporary disabling
until they are fixed.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84241
2020-07-21 15:32:46 +00:00
Jon Roelofs dc09c65f63 LoopIdiomRecognize: use ExpandedValuesCleaner in another place
This is a necessary cleanup after having expanded a SCEV.

See: https://reviews.llvm.org/D84071#inline-774728

Differential Revision: https://reviews.llvm.org/D84174
2020-07-21 09:32:23 -06:00
Jon Roelofs 4d75cc4b0a More conservatively report status from LoopIdiomRecognize
Being "precise" here is getting us into trouble with one of the
EXPENSIVE_CHECKS buildbots, see [1].  Rather than reporting IR additions that
later get rolled back as "no change", instead we now conservatively report that
there was.

1: http://lists.llvm.org/pipermail/llvm-dev/2020-July/143509.html

Differential Revision: https://reviews.llvm.org/D84071
2020-07-21 09:32:22 -06:00
Chris Morin 28da5759bd Fix typo in tutorial 2020-07-21 17:28:24 +02:00
Mitch Phillips 4f029d1be4 [GWP-ASan] Split the unwinder into segv/non-segv.
Note: Resubmission with frame pointers force-enabled to fix builds with
-DCOMPILER_RT_BUILD_BUILTINS=False

Summary:
Splits the unwinder into a non-segv (for allocation/deallocation traces) and a
segv unwinder. This ensures that implementations can select an accurate, slower
unwinder in the segv handler (if they choose to use the GWP-ASan provided one).
This is important as fast frame-pointer unwinders (like the sanitizer unwinder)
don't like unwinding through signal handlers.

Reviewers: morehouse, cryptoad

Reviewed By: morehouse, cryptoad

Subscribers: cryptoad, mgorny, eugenis, pcc, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D83994
2020-07-21 08:25:37 -07:00
Sander de Smalen 9bacf15885 [AArch64][SVE] Fix PCS for functions taking/returning scalable types.
The default calling convention needs to save/restore the SVE callee
saves according to the SVE PCS when the function takes or returns
scalable types, even when the `aarch64_sve_vector_pcs` CC is not
specified for the function.

Reviewers: efriedma, paulwalker-arm, david-arm, rengolin

Reviewed By: paulwalker-arm

Differential Revision: https://reviews.llvm.org/D84041
2020-07-21 15:55:39 +01:00
MaheshRavishankar 44e1a93ccf [mlir][SPIR-V] Adding rationale for not using memref descriptors
SPIR-V lowering does not use `MemrefDescriptor`s when lowering memref
types. This adds rationale for the choice made.

Differential Revision: https://reviews.llvm.org/D84184
2020-07-21 07:28:59 -07:00
George Mitenkov 61dd481f11 [MLIR][LLVMDialect] SelectionOp conversion pattern
This patch introduces conversion pattern for `spv.selection` op.
The conversion can only be applied to selection with all blocks being
reachable. Moreover, selection with control attributes "Flatten" and
"DontFlatten" is not supported.
Since the `PatternRewriter` hook for block merging has not been implemented
for `ConversionPatternRewriter`, merge and continue blocks are kept
separately.

Reviewed By: antiagainst, ftynse

Differential Revision: https://reviews.llvm.org/D83860
2020-07-21 17:11:46 +03:00
Bruno Ricci 7b5bddfd03
[clang] Partially revert "Disable a few formatting options for test/"
The changes to "AlignTrailingComments" and "CommentPragmas" did not
result in what I expected (just leave the special comments alone).

Instead now the following:
  void test() {
    int i; // expected-error
           // expected-warning
  }

is formatted into:
  void test() {
    int i; // expected-error
    // expected-warning
  }

which is even worse.
2020-07-21 14:53:37 +01:00
AndreyChurbanov 617787ea77 [OpenMP] add missed REQUIRES:ompt for 2 OMPT tests 2020-07-21 16:31:17 +03:00
Louis Dionne 14c4de13e9 [compiler-rt] Use -nostdinc++ in clang_rt.profile to avoid including C++ headers
Most of the code in compiler_rt is C code. However, clang_rt.profile
contains the InstrProfilingRuntime.cpp file, which builds as C++. This
means that including e.g. <stdint.h> will actually include libc++'s
<stdint.h> and then #include_next the system's <stdint.h>. However, if
the target we're building compiler-rt for isn't supported by libc++,
this will lead to a failure since libc++'s <stdint.h> includes <__config>,
which performs various checks.

Since the goal seems to *not* be including any header from the C++ Standard
Library in clang_rt.profile, using -nostdinc++ to ensure that doesn't
happen unknowingly seems to make sense.

rdar://65852694

Differential Revision: https://reviews.llvm.org/D84205
2020-07-21 09:14:33 -04:00
AndreyChurbanov 5a8779169e [OpenMP] libomp build fix without OMPT_SUPPORT 2020-07-21 16:03:17 +03:00
Petre-Ionut Tudor 1af9fc8213 [ARM] Generate [SU]HADD from ((a + b) >> 1)
Summary:
Teach LLVM to recognize the above pattern, where the operands are
either signed or unsigned types.

Subscribers: kristof.beyls, hiraditya, danielkiss, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83777
2020-07-21 13:22:07 +01:00
Raphael Isemann 5c15426d7c [lldb] Remove FormattersContainer's name member
Summary:

FormattersContainer currently has an unused `m_name` member. Usually LLDB allows
giving objects names, but for the FormattersContainer it seems excessive. There
are only 4 FormattersContainer variables in LLDB and they are not usually passed
around, so one can always just go up a few frames when debugging to find out
which FormattersContainer you're dealing with.

Reviewers: mib, davide

Reviewed By: mib

Subscribers: JDevlieghere

Differential Revision: https://reviews.llvm.org/D84154
2020-07-21 13:54:38 +02:00
Muhammad Omair Javaid b621e8c787 [LLDB] Fix build on windows caused by LinuxPTraceDefines_arm64sve.h
This patch fixes build on lldb-x64-windows-ninja. The error is caused by
use of two leading underscores.

According to MSVC documentation:
In Microsoft C++, identifiers with two leading underscores are reserved
for compiler implementations.

https://docs.microsoft.com/en-us/cpp/cpp/keywords-cpp?view=vs-2019
2020-07-21 16:47:25 +05:00