platform/upstream/llvm.git
3 years ago[libomptarget] Fixed MSVC build fail caused by __attribute__((used)).
Vyacheslav Zakharin [Wed, 24 Feb 2021 00:57:27 +0000 (16:57 -0800)]
[libomptarget] Fixed MSVC build fail caused by __attribute__((used)).

Differential Revision: https://reviews.llvm.org/D97348

3 years ago[MC][ARM] add .w suffixes for BL (T1) and DBG
Nick Desaulniers [Wed, 24 Feb 2021 17:47:18 +0000 (09:47 -0800)]
[MC][ARM] add .w suffixes for BL (T1) and DBG

F1.2 Standard assembler syntax fields
describes .w and .n suffixes for wide and narrow encodings.

arch/arm/probes/kprobes/test-thumb.c tests installing kprobes for
certain instructions using inline asm.  There's a few instructions we
fail to assemble due to missing .w t2InstAliases.

Adds .w suffixes for:
* bl  (F5.1.25 BL, BLX (immediate) T1)
* dbg (F5.1.42 DBG T1)

Reviewed By: DavidSpickett

Differential Revision: https://reviews.llvm.org/D97236

3 years ago[AArch64] Do not fold SP adjustments into pre-increment addr modes if it overflows...
Amara Emerson [Thu, 21 Jan 2021 22:54:26 +0000 (14:54 -0800)]
[AArch64] Do not fold SP adjustments into pre-increment addr modes if it overflows the redzone.

Instead of outright disabling this completely with the noredzone attribute,
we only avoid doing the optimization if there are memory operations between
the adjustment and the load/store that the adjustment would be folded into.
This avoids the case of something like a stack cookie being corrupted if an
exception happens before the pre-increment to the SP occurs.

This also prevents the folding happening if we have a redzone, but the offset
being folded is above the redzone amount (128 bytes in this case).

rdar://73269336

Differential Revision: https://reviews.llvm.org/D95179

3 years ago[flang] add attribute to trim runtime implementation establish call
Jean Perier [Wed, 24 Feb 2021 17:53:03 +0000 (18:53 +0100)]
[flang] add attribute to trim runtime implementation establish call

CFI allocatable attribute is needed so that the descriptor for the
result can be allocated/deallocated.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D97395

3 years ago[tests] precommit tests for an upcoming AA improvement
Philip Reames [Wed, 24 Feb 2021 17:50:33 +0000 (09:50 -0800)]
[tests] precommit tests for an upcoming AA improvement

3 years ago[OpenMP][Tests][NFC] rename macro to avoid naming clash
Joachim Protze [Wed, 24 Feb 2021 17:45:47 +0000 (18:45 +0100)]
[OpenMP][Tests][NFC] rename macro to avoid naming clash

Rename a macro use missed in e0f3acc5d34aa

3 years ago[OpenMP] Fixed a crash when offloading to x86_64 with target nowait
Shilei Tian [Wed, 24 Feb 2021 17:37:22 +0000 (12:37 -0500)]
[OpenMP] Fixed a crash when offloading to x86_64 with target nowait

PR#49334 reports a crash when offloading to x86_64 with `target nowait`,
which is caused by referencing a nullptr. The root cause of the issue is, when
pushing a hidden helper task in `__kmp_push_task`, it also maps the gtid to its
shadow gtid, which is wrong.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D97329

3 years ago[OpenMP][Tests][NFC] lit might also be known as llvm-lit.py
Joachim Protze [Wed, 24 Feb 2021 17:32:16 +0000 (18:32 +0100)]
[OpenMP][Tests][NFC] lit might also be known as llvm-lit.py

3 years agoRevert "[tests] Mark an autogened test as such"
Philip Reames [Wed, 24 Feb 2021 17:25:19 +0000 (09:25 -0800)]
Revert "[tests] Mark an autogened test as such"

This reverts commit 43a569faeb332ae8b355fffc33eec1ef6e33052e.

Unhelpfully, the tool just added the header and didn't actually update any of the tests.  I didn't notice until after pushing.

3 years agoMake sure some types are indeed trivially_copyable per llvm::is_trivially_copyable
serge-sans-paille [Thu, 11 Feb 2021 20:34:29 +0000 (21:34 +0100)]
Make sure some types are indeed trivially_copyable per llvm::is_trivially_copyable

Test a few types used as llvm::SmallVector parameter. It is important to ensure
we have a consistent behavior for these types to prevent ABI issues as the one
we met in https://bugs.llvm.org/show_bug.cgi?id=39427.

Differential Revision: https://reviews.llvm.org/D96536

3 years ago[libomptarget] Load images in order of registration
Manoel Roemmer [Wed, 24 Feb 2021 17:14:35 +0000 (18:14 +0100)]
[libomptarget] Load images in order of registration

This makes sure that images are loaded in the order in which they are registered with libomptarget.

If a target can load multiple images and these images depend on each other (for example if one image contains the programs target regions and one image contains library code), then the order in which images are loaded can be important for symbol resolution (for example, in the VE plugin).
In this case: because the same code exist in the host binaries, the order in which the host linker loads them (which is also the order in which images are registered with libomptarget) is the order in which the images have to be loaded onto the device.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D95530

3 years ago[tests] Mark an autogened test as such
Philip Reames [Wed, 24 Feb 2021 17:15:02 +0000 (09:15 -0800)]
[tests] Mark an autogened test as such

3 years ago[OpenMP][Tests][NFC] rename macro to avoid naming clash
Joachim Protze [Wed, 24 Feb 2021 17:12:06 +0000 (18:12 +0100)]
[OpenMP][Tests][NFC] rename macro to avoid naming clash

Rename a macro and macro use missed in 35ab6d6390ecd

3 years ago[AMDGPU] Add a bit more gfx90a test coverage
Jay Foad [Wed, 24 Feb 2021 12:07:22 +0000 (12:07 +0000)]
[AMDGPU] Add a bit more gfx90a test coverage

Update the GlobalISel version of llvm.amdgcn.workitem.id.ll to mostly
match the SelctionDAG version.

Differential Revision: https://reviews.llvm.org/D97377

3 years ago[OpenMP][Tests][NFC] rename macro to avoid naming clash
Joachim Protze [Wed, 24 Feb 2021 16:54:50 +0000 (17:54 +0100)]
[OpenMP][Tests][NFC] rename macro to avoid naming clash

When including <ostream>, the register_callback macro of the OMPT callback.h
clashes with a function defined in ostream. This patch renames the macro
and includes ompt into the macro name.

3 years ago[libc][NFC] Exclude few targets from the `all` target.
Siva Chandra Reddy [Wed, 24 Feb 2021 15:22:58 +0000 (07:22 -0800)]
[libc][NFC] Exclude few targets from the `all` target.

3 years ago[libc++] NFC: Fix a few tests in tuple that would succeed trivially
Louis Dionne [Wed, 24 Feb 2021 16:33:41 +0000 (11:33 -0500)]
[libc++] NFC: Fix a few tests in tuple that would succeed trivially

3 years ago[libc++] NFC: Fix a few tests in pair that would succeed trivially
Louis Dionne [Wed, 24 Feb 2021 16:22:37 +0000 (11:22 -0500)]
[libc++] NFC: Fix a few tests in pair that would succeed trivially

3 years ago[flang][fir] Add zero_bits operation.
Eric Schweitz [Tue, 23 Feb 2021 21:09:10 +0000 (13:09 -0800)]
[flang][fir] Add zero_bits operation.

This patch adds the new zero_bits operation and upstrams other changes
including the following:

  - update tablegen syntax to newer forms
  - update memory effects annotations
  - update documentation [NFC]
  - other NFC, such as whitespace and formatting

Differential revision: https://reviews.llvm.org/D97331

3 years ago[clang-tidy] Fix readability-avoid-const-params-in-decls removing const in template...
Nathan James [Wed, 24 Feb 2021 15:54:10 +0000 (15:54 +0000)]
[clang-tidy] Fix readability-avoid-const-params-in-decls removing const in template paramaters

Fixes https://bugs.llvm.org/show_bug.cgi?id=38035

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D96209

3 years ago[mlir] Add polynomial approximation for math::LogOp (using builders API)
Eugene Zhulenev [Wed, 24 Feb 2021 14:59:28 +0000 (06:59 -0800)]
[mlir] Add polynomial approximation for math::LogOp (using builders API)

Replace math::LogOp with an approximations from the the Julien Pommier's SSE math library

Link: http://gruntthepeon.free.fr/ssemath
Reviewed By: asaadaldien

Differential Revision: https://reviews.llvm.org/D97304

3 years ago[libc][NFC] Remove headergen for the cacheline size macro.
Siva Chandra Reddy [Wed, 24 Feb 2021 08:05:53 +0000 (00:05 -0800)]
[libc][NFC] Remove headergen for the cacheline size macro.

We want to be able to build and test the string functions in contexts
like that of Fuchsia where LLVM pieces like tablegen are not available.
Since header generation uses tablegen, we are removing the dependency on
headergen here.

Reviewed By: gchatelet

Differential Revision: https://reviews.llvm.org/D97363

3 years ago[clang-tidy][test] Allow specifying potentially unused suffixes
Nathan James [Wed, 24 Feb 2021 15:22:53 +0000 (15:22 +0000)]
[clang-tidy][test] Allow specifying potentially unused suffixes

If a check-suffix is only required for a CHECK-FIXES or CHECK-MESSAGES. check_clang_tidy will pass the prefixes CHECK-FIXES<...> and CHECK-MESSAGES<...> to FileCheck.
This will result in a FileCheck failing because of an unused prefix.

This addresses the problem by not passing unused prefixes. Its also possible to fix this be passing `--allow-unused-prefixes` flag to FileCheck, but seeing as we have already done the legwork in the script to see its unused, this fix seems the better way to go.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D97322

3 years ago[Coverage][Unittest] Fix stringref issue
Jinsong Ji [Wed, 24 Feb 2021 14:27:23 +0000 (14:27 +0000)]
[Coverage][Unittest] Fix stringref issue

We will pass StringRef and change it in reader.
But we reuse the same Filename vector without clear it,
so in some systems, we may clobbeer previous results.

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D97353

3 years ago[lld-macho] Add REQUIRES to incompatible-arch-tapi test
Jez Ng [Wed, 24 Feb 2021 14:42:52 +0000 (09:42 -0500)]
[lld-macho] Add REQUIRES to incompatible-arch-tapi test

3 years ago[InstructionCost] NFC: Fix up missing cases in LoopVectorize and CodeGenPrep.
Sander de Smalen [Wed, 24 Feb 2021 11:54:18 +0000 (11:54 +0000)]
[InstructionCost] NFC: Fix up missing cases in LoopVectorize and CodeGenPrep.

This fixes the types of a few more cost variables to be of type InstructionCost.

3 years agoRevert "[ValueTracking] computeKnownBitsFromShiftOperator - remove non-zero shift...
Nico Weber [Wed, 24 Feb 2021 14:06:12 +0000 (09:06 -0500)]
Revert "[ValueTracking] computeKnownBitsFromShiftOperator - remove non-zero shift amount handling."

This reverts commit d37400168ce2f1f9ccc91847431f5b8c020a7d67.
Breaks Analysis/./AnalysisTests/ComputeKnownBitsTest.KnownNonZeroShift

3 years ago[ValueTracking] computeKnownBitsFromShiftOperator - remove non-zero shift amount...
Simon Pilgrim [Wed, 24 Feb 2021 13:49:00 +0000 (13:49 +0000)]
[ValueTracking] computeKnownBitsFromShiftOperator - remove non-zero shift amount handling.

This no longer affects any tests after the improvements to the KnownBits shift helpers.

3 years ago[mlir] Add a builder to `linalg.tiled_loop`.
Alexander Belyaev [Wed, 24 Feb 2021 10:39:25 +0000 (11:39 +0100)]
[mlir] Add a builder to `linalg.tiled_loop`.

https://llvm.discourse.group/t/rfc-add-linalg-tileop/2833

Differential Revision: https://reviews.llvm.org/D97372

3 years ago[lldb] Prevent double new lines behind errors/warning/messages from LLDB commands
Raphael Isemann [Wed, 24 Feb 2021 13:08:49 +0000 (14:08 +0100)]
[lldb] Prevent double new lines behind errors/warning/messages from LLDB commands

The current API for printing errors/warnings/messages from LLDB commands
sometimes adds newlines behind the messages for the caller. However, this
happens unconditionally so when the caller already specified a trailing newline
in the error message (or is trying to print a generated error message that ends
in a newline), LLDB ends up printing both the automatically added newline and
the one that was in the error message string. This leads to all the randomly
appearing new lines in error such as:

```
(lldb) command a
error: 'command alias' requires at least two arguments
(lldb) apropos a b
error: 'apropos' must be called with exactly one argument.

(lldb) why is there an empty line behind the second error?
```

This code adds a check that only appends the new line if the passed message
doesn't already contain a trailing new line.

Also removes the AppendRawWarning which had only one caller and doesn't serve
any purpose now.

Reviewed By: #lldb, mib

Differential Revision: https://reviews.llvm.org/D96947

3 years ago[AMDGPU] Add more PAL metadata register names
Jay Foad [Fri, 29 Jan 2021 16:03:30 +0000 (16:03 +0000)]
[AMDGPU] Add more PAL metadata register names

Add all the registers that are currently used by
LLPC: https://github.com/GPUOpen-Drivers/llpc

This only affects disassembly of PAL metadata generated by LLPC and
similar frontends.

Differential Revision: https://reviews.llvm.org/D95619

3 years ago[mlir] Specify cuda-runner pass pipeline as command line options.
Christian Sigg [Sat, 20 Feb 2021 21:16:56 +0000 (22:16 +0100)]
[mlir] Specify cuda-runner pass pipeline as command line options.

The cuda-runner registers two pass pipelines for nested passes,
so that we don't have to use verbose textual pass pipeline specification.

Reviewed By: herhut

Differential Revision: https://reviews.llvm.org/D97091

3 years ago[AMDGPU] Update s_sendmsg messages
Jay Foad [Mon, 25 Jan 2021 17:40:56 +0000 (17:40 +0000)]
[AMDGPU] Update s_sendmsg messages

Update the list of s_sendmsg messages known to the assembler and
disassembler and validate the ones that were added or removed in gfx9
and gfx10.

Differential Revision: https://reviews.llvm.org/D97295

3 years ago[lldb][NFC] Move trivial ValueObject getters/setters to the header
Raphael Isemann [Wed, 24 Feb 2021 13:03:30 +0000 (14:03 +0100)]
[lldb][NFC] Move trivial ValueObject getters/setters to the header

NFC refactoring that moves the definitions of all the trivial getters/setters to the header file
which is what we usually do in LLVM.

Reviewed By: #lldb, JDevlieghere

Differential Revision: https://reviews.llvm.org/D97298

3 years ago[lldb][NFC] Rename the second ValueObjectManager to ValueObjectUpdater and remove...
Raphael Isemann [Wed, 24 Feb 2021 12:26:45 +0000 (13:26 +0100)]
[lldb][NFC] Rename the second ValueObjectManager to ValueObjectUpdater and remove the dead code

`ValueObject.h` contains the `ValueObject::ValueObjectManager` type which is
just a typedef for the ClusterManager that takes care of the whole ValueObject
memory management. However, there is also `ValueObjectManager` defined in the
same header which is only used in the curses UI implementation and consists
mostly of dead and completely untested code.

This code been around since a while (it was added in 2016 as
8369b28da0750129ababae357bea98940800a0e0), so I think we shouldn't just revert
the whole patch.

Instead this patch just moves the class to its own header that it isn't just
hiding in the ValueObject header and renames it to `ValueObjectUpdater` that it
at least has a unique name (which I hope also slightly better reflects the
purpose of this class). I also deleted all the dead code branches and functions.

Reviewed By: #lldb, mib, JDevlieghere

Differential Revision: https://reviews.llvm.org/D97287

3 years ago[OpenCL] Allow taking address of functions as an extension.
Anastasia Stulova [Wed, 24 Feb 2021 12:27:15 +0000 (12:27 +0000)]
[OpenCL] Allow taking address of functions as an extension.

When '__cl_clang_function_pointers' extension is enabled
the parser should allow obtaining the function address.

This fixes PR49264!

Differential Revision: https://reviews.llvm.org/D97203

3 years ago[lldb] Add asserts that prevent construction of cycles in the decl origin tracking
Raphael Isemann [Wed, 24 Feb 2021 12:25:18 +0000 (13:25 +0100)]
[lldb] Add asserts that prevent construction of cycles in the decl origin tracking

LLDB tracks where any imported `clang::Decl` originally came from via a simple
map from 'imported decl' to 'original decl'. That information is used to later
complete parts of the Decl when more information is requested about a certain
Decl (e.g., via the ExternalASTSource interface from Clang).

When finding the 'original decl' for a given decl, the ASTImporterDelegate
essentially just recursively follows the previously mentioned map from
'imported' to 'original decl' until it can find any further 'original decl'. The
final found decl is then the one that will be imported. The recursion is
necessary as in LLDB we don't just import decls from one ASTContext to another,
but also from one ASTContext to another via a (potentially temporary)
ASTContext. For example, the expression parser creates a temporary ASTContext
for parsing the current expression.

The problem with the recursion is however that if we somehow get a cycle into
our mapping, then the ASTImporterDelegate will just infinite recurse. As the
infinite recursion usually happens after the cycle was already created in a code
path such as completing a type, the crash backtraces we get for these bugs are
not very useful. However having the backtrace where the faulty map entry is
created usually makes the code trivial to fix (as there should be some rogue
CopyType call or something similar nearby. See for example D96366).

This patch tries to make these issues easier to track down by putting a bunch of
sanity asserts in the code that fills out the map. All the asserts are just
checking that there is no direct cycle (ASTContext maps to itself) when updating
the origin tracking map.

The assert in the ASTImportDelegate constructor is an `lldbassert` (which also
is getting checked in release builds with disabled asserts) as the code path
there is pretty cold and we can reliably detect a rogue CopyType call from
there.

I also had to update some code in
`ClangASTImporter::ASTImporterDelegate::Imported`. This code already had a
safety check for creating a cycle in the origin tracking map, but it still
constructed an ASTImporter while checking for the cycle (by requesting a
delegate via `GetDelegate` and passing two identical ASTContexts which looks
like a rogue CopyType call to the checks).

Reviewed By: shafik

Differential Revision: https://reviews.llvm.org/D97300

3 years ago[ValueTracking] ComputeKnownBits - minimum leading/trailing zero bits in LSHR/SHL...
Simon Pilgrim [Wed, 24 Feb 2021 12:12:43 +0000 (12:12 +0000)]
[ValueTracking] ComputeKnownBits - minimum leading/trailing zero bits in LSHR/SHL (PR44526)

Followup to D72573 - as detailed in https://blog.regehr.org/archives/1709 we don't make use of the known leading/trailing zeros for shifted values in cases where we don't know the shift amount value.

Stop ValueTracking returning zero for poison shift patterns and use the KnownBits shift helpers directly.

Extend KnownBits::shl to combine all possible shifted combinations if both min/max shift amount values are in range.

Differential Revision: https://reviews.llvm.org/D90479

3 years ago[asan] Avoid putting globals in a comdat section when targetting elf.
Pierre Gousseau [Wed, 24 Feb 2021 12:01:56 +0000 (12:01 +0000)]
[asan] Avoid putting globals in a comdat section when targetting elf.

Putting globals in a comdat for dead-stripping changes the semantic and
can potentially cause false negative odr violations at link time.
If odr indicators are used, we keep the comdat sections, as link time
odr violations will be dectected for the odr indicator symbols.

This fixes PR 47925

3 years ago[Utils] collectBitParts - add truncate() handling
Simon Pilgrim [Wed, 24 Feb 2021 11:48:03 +0000 (11:48 +0000)]
[Utils] collectBitParts - add truncate() handling

3 years ago[docs][JITLink] Remove the JITLink doc for now.
Lang Hames [Wed, 24 Feb 2021 11:32:18 +0000 (22:32 +1100)]
[docs][JITLink] Remove the JITLink doc for now.

I'll reinstate and continue investigation tomorrow.

3 years ago[docs][JITLink] Yet more experiments to try to understand sphinx error.
Lang Hames [Wed, 24 Feb 2021 11:22:16 +0000 (22:22 +1100)]
[docs][JITLink] Yet more experiments to try to understand sphinx error.

3 years ago[docs][JITLink] More experiments to try to understand sphinx error.
Lang Hames [Wed, 24 Feb 2021 11:14:17 +0000 (22:14 +1100)]
[docs][JITLink] More experiments to try to understand sphinx error.

3 years ago[dexter] Force dexter tests to use the host triple
OCHyams [Wed, 24 Feb 2021 11:09:18 +0000 (11:09 +0000)]
[dexter] Force dexter tests to use the host triple

If the default target and host triple don't match then print the following
message when the lit test runs:

    Forcing dexter tests to use host triple {HOST_TRIPLE}.

If we can't target the host arch then, when lit runs, we mark
the dexter test directories as UNSUPPORTED and print the message:

    Host triple {HOST_TRIPLE} not supported. Skipping dexter tests in
    the debuginfo-tests project.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D96494

3 years ago[clangd] Fix a race
Kadir Cetinkaya [Wed, 24 Feb 2021 09:42:42 +0000 (10:42 +0100)]
[clangd] Fix a race

Differential Revision: https://reviews.llvm.org/D97366

3 years ago[DAG] Add basic mul-with-overflow constant folding support
Simon Pilgrim [Wed, 24 Feb 2021 11:08:49 +0000 (11:08 +0000)]
[DAG] Add basic mul-with-overflow constant folding support

As noticed on D97160

3 years ago[docs][JITLink] Make ``ObjectLinkingLayer`` not a paragraph start.
Lang Hames [Wed, 24 Feb 2021 11:04:14 +0000 (22:04 +1100)]
[docs][JITLink] Make ``ObjectLinkingLayer`` not a paragraph start.

More experiments as I try to placate sphinx.

3 years ago[docs][JITLink] Return to `` for inline literals.
Lang Hames [Wed, 24 Feb 2021 10:55:49 +0000 (21:55 +1100)]
[docs][JITLink] Return to `` for inline literals.

Also awkwardly reformat text to test whether the error is occurring
on the line with the '::', or the previous one.

3 years ago[docs][JITLink] Try explicit literal blocks for monospace list elements.
Lang Hames [Wed, 24 Feb 2021 10:47:20 +0000 (21:47 +1100)]
[docs][JITLink] Try explicit literal blocks for monospace list elements.

3 years ago[docs][JITLink] More attempted fixes for formatting issues in the JITLink doc.
Lang Hames [Wed, 24 Feb 2021 10:40:01 +0000 (21:40 +1100)]
[docs][JITLink] More attempted fixes for formatting issues in the JITLink doc.

Try using the literal domain for `ObjectLinkingLayer::Plugin` and literal
blocks for multi-line method names.

3 years agoRecommit "[LV] Allow tryToCreateWidenRecipe to return a VPValue, use for blends."
Florian Hahn [Wed, 24 Feb 2021 09:55:39 +0000 (09:55 +0000)]
Recommit "[LV] Allow tryToCreateWidenRecipe to return a VPValue, use for blends."

This reverts the revert commit 437f0bbcd509d0ed71b91ec1f86f48c2f4aae980.

It adds a new toVPRecipeResult, which forces VPRecipeOrVPValueTy to be
constructed with a VPRecipeBase *. This should address ambiguous
constructor issues for recipe sub-types that also inherit from VPValue.

3 years ago[mlir][linalg] Fix Linalg roundtrip test.
Alexander Belyaev [Wed, 24 Feb 2021 10:22:10 +0000 (11:22 +0100)]
[mlir][linalg] Fix Linalg roundtrip test.

The test did not check whether the operations can be parsed again after
printing them once.

Differential Revision: https://reviews.llvm.org/D97368

3 years agoUpdate REQUIRES line in 4 tests that attempt to use arm64 which should be aarch64...
Douglas Yung [Wed, 24 Feb 2021 10:24:26 +0000 (02:24 -0800)]
Update REQUIRES line in 4 tests that attempt to use arm64 which should be aarch64 not arm.

3 years ago[docs][JITLink] Sphinx does not like '::' in monotype. Try using a
Lang Hames [Wed, 24 Feb 2021 10:23:10 +0000 (21:23 +1100)]
[docs][JITLink] Sphinx does not like '::' in monotype. Try using a
cpp domain expr instead.

3 years ago[docs][JITLink] Add a JITLink design and API document.
Lang Hames [Wed, 24 Feb 2021 10:04:35 +0000 (21:04 +1100)]
[docs][JITLink] Add a JITLink design and API document.

3 years ago[JITLink] Add assertions, fix a comment.
Lang Hames [Wed, 24 Feb 2021 08:17:35 +0000 (19:17 +1100)]
[JITLink] Add assertions, fix a comment.

The new assertions check that Addressables removed when removing
external or absolute symbols are not referenced by another symbol.

A comment on post-fixup passes is updated: vmaddrs have all been
set up by the time the pre-fixup passes are run, post-fixup passes
run after fixups have been applied to content.

3 years ago[JITLink] Fix comments about JITLink's generic link algorithm.
Lang Hames [Wed, 24 Feb 2021 08:16:16 +0000 (19:16 +1100)]
[JITLink] Fix comments about JITLink's generic link algorithm.

These comments had gotten out of date with the code.

3 years ago[AArch64] Use CMTST for != 0 vector compares (vnot (CMEQz A)).
Florian Hahn [Wed, 24 Feb 2021 09:30:30 +0000 (09:30 +0000)]
[AArch64] Use CMTST for != 0 vector compares (vnot (CMEQz A)).

(CMTST A, A) will only set elements to 0 if the element is 0 in A. Use
it for != 0 compares, which currently use (vnot (CMEQz A)). This saves a
mvn instruction.

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D97303

3 years ago[OpenCL] Add ndrange builtin functions to TableGen
Sven van Haastregt [Wed, 24 Feb 2021 09:27:22 +0000 (09:27 +0000)]
[OpenCL] Add ndrange builtin functions to TableGen

Also ensure all kernel enqueue functions have CL 2.0 as minimum
version.

Differential Revision: https://reviews.llvm.org/D97060

3 years ago[OpenCL] Add declarations with enum/typedef args
Sven van Haastregt [Wed, 24 Feb 2021 09:27:13 +0000 (09:27 +0000)]
[OpenCL] Add declarations with enum/typedef args

Add the remaining missing builtin function declarations that have enum
or typedef argument or return types.

Differential Revision: https://reviews.llvm.org/D96860

3 years ago[libcxx] [test] Don't pass INCLUDE to clang via -isystem
Martin Storsjö [Thu, 22 Oct 2020 09:08:33 +0000 (09:08 +0000)]
[libcxx] [test] Don't pass INCLUDE to clang via -isystem

Passing the MSVC include dirs via -isystem makes them included before
clang's own include resource dir (<prefix>/lib/clang/<version>/include).
This causes includes of stddef.h to bypass clang's stddef.h which
defines max_align_t, which libc++ needs defined.

This was added in 4372f06d0fcaba1a6913e2f37be064e06a7b5b5b when the
initial windows testing support was added, and has been brought along
since. It's unclear if this was needed back then - now it no longer is
needed at least, and since libc++ started depending on max_align_t, this
became an issue.

Differential Revision: https://reviews.llvm.org/D97167

3 years ago[LLD] [COFF] Allow invoking lib.exe mode via -lib in addition to /lib
Martin Storsjö [Mon, 15 Feb 2021 11:30:18 +0000 (13:30 +0200)]
[LLD] [COFF] Allow invoking lib.exe mode via -lib in addition to /lib

Remove a stray -lib argument in guardcf-lto.ll; llvm-lib doesn't
support generating import libs from a def file unlike lib.exe.
Previously this worked because the -lib argument was ignored
(printing only a warning).

Differential Revision: https://reviews.llvm.org/D96699

3 years ago[ARM] Expand the range of allowed post-incs in load/store optimizer
David Green [Wed, 24 Feb 2021 08:46:15 +0000 (08:46 +0000)]
[ARM] Expand the range of allowed post-incs in load/store optimizer

Currently the load/store optimizer will only fold in increments of the
same size as the load/store. This patch expands that to any legal
immediate for the post-inc instruction.

This is a recommit of 3b34b06fc5908b with correctness fixes and extra
tests.

Differential Revision: https://reviews.llvm.org/D95885

3 years agoRevert "[InstrProfiling] Use nobits as __llvm_prf_cnts section type in ELF"
Petr Hosek [Wed, 24 Feb 2021 08:37:54 +0000 (00:37 -0800)]
Revert "[InstrProfiling] Use nobits as __llvm_prf_cnts section type in ELF"

This reverts commit 6b286d93f7ec8518c685a302269e44b06a0a24f3 because
in some cases when the optimizer evaluates the global initializer,
__llvm_prf_cnts may not be entirely zero initialized.

3 years ago[libc++] [docs] [C++2b] Update status page with papers adopted in February 2021 virtu...
Marek Kurdej [Wed, 24 Feb 2021 08:40:33 +0000 (09:40 +0100)]
[libc++] [docs] [C++2b] Update status page with papers adopted in February 2021 virtual meeting.

3 years agoAdd REQUIRES aarch64 to test incompatible-arch.s since it fails if that target is...
Douglas Yung [Wed, 24 Feb 2021 08:02:21 +0000 (00:02 -0800)]
Add REQUIRES aarch64 to test incompatible-arch.s since it fails if that target is not built.

This should fix the PS4 linux buildbot failure: http://lab.llvm.org:8011/#/builders/139/builds/63

3 years ago[LegalizeIntegerTypes] Use GetExpandedInteger instead of SplitInteger in ExpandIntRes...
Craig Topper [Wed, 24 Feb 2021 07:52:01 +0000 (23:52 -0800)]
[LegalizeIntegerTypes] Use GetExpandedInteger instead of SplitInteger in ExpandIntRes_XMULO.

We know the input is going to be expanded as well, so we should
just ask for the already expanded operands. Otherwise we create
nodes that are just going to need to be legalized.

3 years ago[Test][AArch64] Test SADDO/SSUBO narrowing legalization
Cassie Jones [Wed, 24 Feb 2021 07:40:58 +0000 (02:40 -0500)]
[Test][AArch64] Test SADDO/SSUBO narrowing legalization

Reviewed By: aemerson

Differential Revision: https://reviews.llvm.org/D96675

3 years ago[asan] Increase CHECK limit in __sanitizer_annotate_contiguous_container
Vitaly Buka [Wed, 24 Feb 2021 00:44:00 +0000 (16:44 -0800)]
[asan] Increase CHECK limit in __sanitizer_annotate_contiguous_container

Asan allocator already support up to (1 << 40) bytes allocations.

3 years ago[ThinLTO, NewPM] Run OptimizerLastEPCallbacks from buildThinLTOPreLinkDefaultPipeline
Vitaly Buka [Wed, 10 Feb 2021 09:44:05 +0000 (01:44 -0800)]
[ThinLTO, NewPM] Run OptimizerLastEPCallbacks from buildThinLTOPreLinkDefaultPipeline

-O1 and above do dont call real optimizer pipeline in ThinLTO PreLink.
Also clang can't add PostLink OptimizerLastEPCallbacks for in-process ThinLTO.
This results in missing sanitizer passes with ThinLTO.

Simple working solution is just call OptimizerLastEPCallbacks
at the end of buildThinLTOPreLinkDefaultPipeline.

Differential Revision: https://reviews.llvm.org/D96320

3 years agoReduce the number of attributes attached to each function
Dávid Bolvanský [Wed, 24 Feb 2021 06:08:33 +0000 (07:08 +0100)]
Reduce the number of attributes attached to each function

Patch takes advantage of the implicit default behavior to reduce the number of attributes, which in turns reduces compilation time.

Reviewed By: serge-sans-paille

Differential Revision: https://reviews.llvm.org/D97116

3 years agoRevert "patch" it wass my mistake inusing git
xgupta [Wed, 24 Feb 2021 05:34:35 +0000 (11:04 +0530)]
Revert "patch" it wass my mistake inusing git

This reverts commit 3f30cd73795d17f071cc03926fea28943c65f05f.

3 years ago[libc][NFC] Merge llvmlibc and llvmlibm targets in to a single target.
Siva Chandra Reddy [Wed, 24 Feb 2021 05:19:05 +0000 (21:19 -0800)]
[libc][NFC] Merge llvmlibc and llvmlibm targets in to a single target.

The single target is called llvmlibc. We can add back smaller libm and
other targets in future if required.

3 years ago[Docs] Mention clone depth feature of git in LLVM getting started
xgupta [Wed, 24 Feb 2021 05:26:10 +0000 (10:56 +0530)]
[Docs] Mention clone depth feature of git in LLVM getting started

The current size of the llvm-project repository exceeds 1 GB. A shallow clone can save a lot of space and time. Some developers might not aware of this feature.

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D97118

3 years agopatch
xgupta [Mon, 22 Feb 2021 18:44:18 +0000 (00:14 +0530)]
patch

3 years ago[ASan] Introduce a way set different ways of emitting module destructors.
Dan Liew [Wed, 10 Feb 2021 01:01:41 +0000 (17:01 -0800)]
[ASan] Introduce a way set different ways of emitting module destructors.

Previously there was no way to control how module destructors were emitted
by `ModuleAddressSanitizerPass`. However, we want language frontends (e.g. Clang)
to be able to decide how to emit these destructors (if at all).

This patch introduces the `AsanDtorKind` enum that represents the different ways
destructors can be emitted. There are currently only two valid ways to emit destructors.

* `Global` - Use `llvm.global_dtors`. This was the previous behavior and is the default.
* `None`   - Do not emit module destructors.

The `ModuleAddressSanitizerPass` and the various wrappers around it have been updated
to take the `AsanDtorKind` as an argument.

The `-asan-destructor-kind=` command line argument has been introduced to make this
easy to test from `opt`. If this argument is specified it overrides the value passed
to the `ModuleAddressSanitizerPass` constructor.

Note that `AsanDtorKind` is not `bool` because we will introduce a new way to
emit destructors in a subsequent patch.

Note that `AsanDtorKind` is given its own header file because if it is declared
in `Transforms/Instrumentation/AddressSanitizer.h` it leads to compile error
(Module is ambiguous) when trying to use it in
`clang/Basic/CodeGenOptions.def`.

rdar://71609176

Differential Revision: https://reviews.llvm.org/D96571

3 years ago[HIP] Fix managed variable linkage
Yaxun (Sam) Liu [Fri, 5 Feb 2021 19:40:16 +0000 (14:40 -0500)]
[HIP] Fix managed variable linkage

Currently managed variables are emitted as undefined symbols, which
causes difficulty for diagnosing undefined symbols for non-managed
variables.

This patch transforms managed variables in device compilation so that
they can be emitted as normal variables.

Reviewed by: Artem Belevich

Differential Revision: https://reviews.llvm.org/D96195

3 years ago[AArch64][GlobalISel][PostSelectOpt] Constrain reg operands after mutating instructions.
Amara Emerson [Tue, 23 Feb 2021 23:43:29 +0000 (15:43 -0800)]
[AArch64][GlobalISel][PostSelectOpt] Constrain reg operands after mutating instructions.

The non-flag setting variants of instructions may have different regclass
requirements. If so, we need to constrain them.

Differential Revision: https://reviews.llvm.org/D97343

3 years ago[XCOFF] add C_FILE symbol at index 0 of symbol table.
Chen Zheng [Wed, 24 Feb 2021 02:48:58 +0000 (21:48 -0500)]
[XCOFF] add C_FILE symbol at index 0 of symbol table.

This is for XCOFF DWARF support.

Seems when DWARF debug is enable, symbol 0 has special usage
for AIX binder. At least, symbol 0 can not be the .text
section. Otherwise, we get some binding time error.

Add correct C_FILE symbol at index 0 here to make AIX binder
work.

Reviewed By: hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D97117

3 years agoRevert "Add more historic DWARF vendor extensions"
Nico Weber [Wed, 24 Feb 2021 03:10:02 +0000 (22:10 -0500)]
Revert "Add more historic DWARF vendor extensions"

This reverts commit c4a91444689455a35db1e7f50bcd876a3eb86126.
Breaks check-llvm everywhere, see https://reviews.llvm.org/D97242#2583716

3 years ago[lld-macho] Better deduplication of personality pointers
Jez Ng [Wed, 24 Feb 2021 02:42:02 +0000 (21:42 -0500)]
[lld-macho] Better deduplication of personality pointers

{D95809} introduced a mechanism for synthetic symbol creation of personality
pointers. When multiple section relocations referred to the same personality
pointer, it would deduplicate them. However, it neglected to consider that we
could have symbol relocations that also refer to the same personality pointer.
This diff fixes it.

In practice, this mix of relocations arises when there is a statically-linked
personality routine that is referenced from multiple object files. Within the
same object file, it will be referred to via section relocations, but
(obviously) other object files will refer to it via symbol relocations. Failing
to deduplicate these references resulted in us going over the
3-personality-pointer limit when linking some larger applications.

Fixes llvm.org/PR48389.

Reviewed By: #lld-macho, thakis, alexshap

Differential Revision: https://reviews.llvm.org/D97245

3 years ago[lld-macho] Check for arch compatibility when loading ObjFiles and TBDs
Jez Ng [Wed, 24 Feb 2021 02:42:00 +0000 (21:42 -0500)]
[lld-macho] Check for arch compatibility when loading ObjFiles and TBDs

The silent failures had confused me a few times.

I haven't added a similar check for platform yet as we don't yet have logic to
infer the platform automatically, and so adding that check would require
updating dozens of test files.

Reviewed By: #lld-macho, thakis, alexshap

Differential Revision: https://reviews.llvm.org/D97209

3 years ago[lld-macho] Fix semantics & add tests for ARM64 GOT/TLV relocs
Jez Ng [Wed, 24 Feb 2021 02:41:54 +0000 (21:41 -0500)]
[lld-macho] Fix semantics & add tests for ARM64 GOT/TLV relocs

I've adjusted the RelocAttrBits to better fit the semantics of
the relocations. In particular:

1. *_UNSIGNED relocations are no longer marked with the `TLV` bit, even
   though they can occur within TLV sections. Instead the `TLV` bit is
   reserved for relocations that can reference thread-local symbols, and
   *_UNSIGNED relocations have their own `UNSIGNED` bit. The previous
   implementation caused TLV and regular UNSIGNED semantics to be
   conflated, resulting in rebase opcodes being incorrectly emitted for TLV
   relocations.

2. I've added a new `POINTER` bit to denote non-relaxable GOT
   relocations. This distinction isn't important on x86 -- the GOT
   relocations there are either relaxable or non-relaxable loads -- but
   arm64 has `GOT_LOAD_PAGE21` which loads the page that the referent
   symbol is in (regardless of whether the symbol ends up in the GOT). This
   relocation must reference a GOT symbol (so must have the `GOT` bit set)
   but isn't itself relaxable (so must not have the `LOAD` bit). The
   `POINTER` bit is used for relocations that *must* reference a GOT
   slot.

3. A similar situation occurs for TLV relocations.

4. ld64 supports both a pcrel and an absolute version of
   ARM64_RELOC_POINTER_TO_GOT. But the semantics of the absolute version
   are pretty weird -- it results in the value of the GOT slot being
   written, rather than the address. (That means a reference to a
   dynamically-bound slot will result in zeroes being written.) The
   programs I've tried linking don't use this form of the relocation, so
   I've dropped our partial support for it by removing the relevant
   RelocAttrBits.

Reviewed By: alexshap

Differential Revision: https://reviews.llvm.org/D97031

3 years ago[lld-macho] Use full input file name in invalid relocation error message
Jez Ng [Wed, 24 Feb 2021 02:41:52 +0000 (21:41 -0500)]
[lld-macho] Use full input file name in invalid relocation error message

Just something I noticed while debugging arm relocations...

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D97078

3 years ago[mlir][Inliner] Don't optimize callees in async mode if there is only one to optimize
River Riddle [Wed, 24 Feb 2021 02:43:55 +0000 (18:43 -0800)]
[mlir][Inliner] Don't optimize callees in async mode if there is only one to optimize

This avoids unnecessary async overhead in situations that won't benefit from it.

3 years ago[Debug-Info][NFC] move emitDwarfUnitLength to MCStreamer class
Chen Zheng [Wed, 24 Feb 2021 02:18:47 +0000 (21:18 -0500)]
[Debug-Info][NFC] move emitDwarfUnitLength to MCStreamer class

We may need to do some customization for DWARF unit length in DWARF
section headers for some targets for some code generation path.

For example, for XCOFF in assembly path, AIX assembler does not require
the debug section containing its debug unit length in the header.

Move emitDwarfUnitLength to MCStreamer class so that we can do
customization in different Streamers

Reviewed By: ikudrin

Differential Revision: https://reviews.llvm.org/D95932

3 years agoAdd more historic DWARF vendor extensions
Adrian Prantl [Wed, 24 Feb 2021 01:52:21 +0000 (17:52 -0800)]
Add more historic DWARF vendor extensions

The maintainer of libdwarf kindly provided this patch with a bunch of
historic DWARF extensions that are missing from Dwarf.def. This list
is helpful to avoid potential conflicts in the user-defined vendor
extension space in the future.

Patch by David Anderson!

Differential Revision: https://reviews.llvm.org/D97242

3 years ago[LoopNest] Use `getUniqueSuccessor()` instead when checking empty blocks
Ta-Wei Tu [Wed, 24 Feb 2021 01:52:46 +0000 (09:52 +0800)]
[LoopNest] Use `getUniqueSuccessor()` instead when checking empty blocks

Blocks that contain only a single branch instruction to the next block can be skipped in analyzing the loop-nest structure.
This is currently done by `getSingleSuccessor()`.
However, the branch instruction might have multiple targets which happen to all be the same.
In this case, the block should still be considered as empty and skipped.

An example is `test/Transforms/LoopInterchange/update-condbranch-duplicate-successors.ll` (the LIT test for this patch is modified from it as well).

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D97286

3 years ago[SimplifyCFG] Update passingValueIsAlwaysUndefined to check more attributes
Juneyoung Lee [Tue, 23 Feb 2021 02:46:59 +0000 (11:46 +0900)]
[SimplifyCFG] Update passingValueIsAlwaysUndefined to check more attributes

This is a simple patch to update SimplifyCFG's passingValueIsAlwaysUndefined to inspect more attributes.

A new function `CallBase::isPassingUndefUB` checks attributes that imply noundef.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D97244

3 years agoRevert "[Driver][Windows] Support per-target runtimes dir layout for profile instr...
Nico Weber [Wed, 24 Feb 2021 01:38:16 +0000 (20:38 -0500)]
Revert "[Driver][Windows] Support per-target runtimes dir layout for profile instr generate"

This reverts commit 7f9d5d6e444c91ce6f2e377b312ac573dfc6779a.
Breaks check-clang everywhere, see https://reviews.llvm.org/D96638#2583608

3 years ago[mlir] ExecutionEngine needs special handling for COFF binaries
Kern Handa [Sun, 21 Feb 2021 09:20:37 +0000 (01:20 -0800)]
[mlir] ExecutionEngine needs special handling for COFF binaries

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D97141

3 years ago[mlir][Inliner] Keep the number of async pass managers constant
River Riddle [Wed, 24 Feb 2021 00:40:09 +0000 (16:40 -0800)]
[mlir][Inliner] Keep the number of async pass managers constant

This prevents a bug in the pass instrumentation implementation where the main thread would end up with a different pass manager in different runs of the pass.

3 years ago[NFC] Make TrailingObjects non-copyable/non-movable
Erich Keane [Tue, 23 Feb 2021 19:58:46 +0000 (11:58 -0800)]
[NFC] Make TrailingObjects non-copyable/non-movable

This got me pretty recently... TrailingObjects cannot be copied or
moved, since they need to be pre-allocated. This patch deletes the copy
and move operations (plus re-adds the default ctor).

Differential Revision: https://reviews.llvm.org/D97324

3 years ago[AArch64][GlobalISel] Correct function evaluation order in applyINS
Jessica Paquette [Wed, 24 Feb 2021 00:12:56 +0000 (16:12 -0800)]
[AArch64][GlobalISel] Correct function evaluation order in applyINS

The order in which the nested calls to Builder.buildWhatever are
evaluated in differs between GCC and Clang.

This caused a bot failure because the MIR in the testcase was
coming out in a different order than expected.

Rather than using nested calls, pull them out in order to fix the
order of evaluation.

3 years agocollectUsedGlobalVariables: migrate SmallPtrSetImpl overload to SmallVecImpl overload...
Fangrui Song [Wed, 24 Feb 2021 00:09:05 +0000 (16:09 -0800)]
collectUsedGlobalVariables: migrate SmallPtrSetImpl overload to SmallVecImpl overload after D97128

And delete the SmallPtrSetImpl overload.

While here, decrease inline element counts from 8 to 4. See D97128 for the choice.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D97257

3 years agoFix unstable SmallPtrSet iteration issues due to collectUsedGlobalVariables
Fangrui Song [Tue, 23 Feb 2021 20:32:08 +0000 (12:32 -0800)]
Fix unstable SmallPtrSet iteration issues due to collectUsedGlobalVariables

While here, decrease inline element counts from 8 to 4. See D97128 for the choice.

Depends on D97128 (which added a new SmallVecImpl overload for collectUsedGlobalVariables).

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D97139

3 years ago[ThinLTO] Make cloneUsedGlobalVariables deterministic
Fangrui Song [Tue, 23 Feb 2021 23:50:45 +0000 (15:50 -0800)]
[ThinLTO] Make cloneUsedGlobalVariables deterministic

Iterating on `SmallPtrSet<GlobalValue *, 8>` with more than 8 elements
is not deterministic. Use a SmallVector instead because `Used` is guaranteed to contain unique elements.

While here, decrease inline element counts from 8 to 4. The number of
`llvm.used`/`llvm.compiler.used` elements is usually 0 or 1. For full
LTO/hybrid LTO, the number may be large, so we need to be careful.

According to tejohnson's analysis https://reviews.llvm.org/D97128#2582399 , 4 is
good for a large project with WholeProgramDevirt, when available_externally
vtables are placed in the llvm.compiler.used set.

Differential Revision: https://reviews.llvm.org/D97128

3 years ago[WPD] Fix handling of pure virtual base class
Teresa Johnson [Sat, 20 Feb 2021 22:09:10 +0000 (14:09 -0800)]
[WPD] Fix handling of pure virtual base class

The fix in 3c4c205060c9398da705eb71b63ddd8a04999de9 caused an assert in
the case of a pure virtual base class. In that case, the vTableFuncs
list on the summary will be empty, so we were hitting the new assert
that the linkage type was not available_externally.

In the case of pure virtual, we do not want to assert, and additionally
need to set VS so that we don't treat it conservatively and quit the
analysis of the type id early.

This exposed a pre-existing issue where we were not updating the vcall
visibility on pure virtual functions when whole program visibility was
specified. We were skipping updating the visibility on any global vars
that didn't have any vTableFuncs, which meant all pure virtual were not
updated, and the later analysis would block any devirtualization of
calls that had a type id used on those pure virtual vtables (see the
handling in the other code modified in this patch). Simply remove that
check. It will mean that we may update the vcall visibility on global
vars that aren't vtables, but that setting is ignored for any global
vars that didn't have type metadata anyway.

Added a new test case that asserted without removing the assert, and
that requires the other fixes in this patch (updateVCallVisibilityInIndex
and not skipping all vtables without virtual funcs) to get a successful
devirtualization with index-only WPD. I added cases to test hybrid and
regular LTO for completeness, although those already worked without the
fixes here.

With this final fix, a clang multistage bootstrap with WPD builds and
runs all tests successfully.

Differential Revision: https://reviews.llvm.org/D97126

3 years ago[RISCV] Add vadd with mask and without mask builtin.
Hsiangkai Wang [Thu, 4 Feb 2021 04:57:44 +0000 (12:57 +0800)]
[RISCV] Add vadd with mask and without mask builtin.

Demonstrate how to add RISC-V V builtins and lower them to IR intrinsics for V extension.

Authored-by: Roger Ferrer Ibanez <rofirrim@gmail.com>
Co-Authored-by: Hsiangkai Wang <kai.wang@sifive.com>
Differential Revision: https://reviews.llvm.org/D93446

3 years ago[libc] Add a standalone flavor of an equivalent of std::string_view.
Siva Chandra Reddy [Tue, 23 Feb 2021 08:13:42 +0000 (00:13 -0800)]
[libc] Add a standalone flavor of an equivalent of std::string_view.

This class is to serve as a replacement for llvm::StringRef as part of
the plans to limit dependency on other parts of LLVM. One use of
llvm::StringRef in MPFRWrapper has been replaced with the new class.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D97330