Commit Graph

6483 Commits

Author SHA1 Message Date
Mehdi Amini f917356f9c Revert "[clang][cli] Port ObjCMTAction to new option parsing system"
This reverts commit 09248a5d25.

Some builds are broken. I suspect a `static constexpr` in a class missing a
definition out of class (required pre-c++17).
2020-11-11 20:01:03 +00:00
Nikita Popov 782a93cc9a [BasicAA] Add test for incorrect BatchAA result (NFC)
BatchAA produces an incorrect result, because a result based on
a temporary phi noalias assumption is cached.
2020-11-11 19:06:42 +01:00
Jan Svoboda 09248a5d25 [clang][cli] Port ObjCMTAction to new option parsing system
Merge existing marhsalling info kinds and add some primitives to
express flag options that contribute to a bitfield.

Depends on D82574

Reviewed By: Bigcheese

Differential Revision: https://reviews.llvm.org/D82860
2020-11-11 13:03:02 +01:00
Michael Kruse e5dba2d7e5 [OMPIRBuilder] Start 'Create' methods with lower case. NFC.
For consistency with the IRBuilder, OpenMPIRBuilder has method names starting with 'Create'. However, the LLVM coding style has methods names starting with lower case letters, as all other OpenMPIRBuilder already methods do. The clang-tidy configuration used by Phabricator also warns about the naming violation, adding noise to the reviews.

This patch renames all `OpenMPIRBuilder::CreateXYZ` methods to `OpenMPIRBuilder::createXYZ`, and updates all in-tree callers.

I tested check-llvm, check-clang, check-mlir and check-flang to ensure that I did not miss a caller.

Reviewed By: mehdi_amini, fghanim

Differential Revision: https://reviews.llvm.org/D91109
2020-11-09 19:35:11 -06:00
Jan Svoboda dbfa69c502 Port some floating point options to new option marshalling infrastructure
This ports a number of OpenCL and fast-math flags for floating point
over to the new marshalling infrastructure.

As part of this, `Opt{In,Out}FFlag` were enhanced to allow other flags to
imply them, via `DefaultAnyOf<>`. For example:
```
defm signed_zeros : OptOutFFlag<"signed-zeros", ...,
  "LangOpts->NoSignedZero",
  DefaultAnyOf<[cl_no_signed_zeros, menable_unsafe_fp_math]>>;
```
defines `-fsigned-zeros` (`false`) and `-fno-signed-zeros` (`true`)
linked to the keypath `LangOpts->NoSignedZero`, defaulting to `false`,
but set to `true` implicitly if one of `-cl-no-signed-zeros` or
`-menable-unsafe-fp-math` is on.

Note that the initial patch was written Daniel Grumberg.

Differential Revision: https://reviews.llvm.org/D82756
2020-11-09 18:00:10 -05:00
Michael Kruse f44ee0f5e7 [OpenMPIRBuilder] Implement CreateCanonicalLoop.
CreateCanonicalLoop generates a standardized control flow structure for OpenMP canonical for loops. The structure can be consumed by loop-associated directives such as worksharing-loop, distribute, simd etc. as well as loop transformations such as tile and unroll.

This is a first design without considering all complexities yet. The control-flow emits more basic block than strictly necessary, but these will be optimized by CFGSimplify anyway, provide a nice separation of concerns and might later be useful with more complex scenarios. I successfully implemented a basic tile construct using this API, which is not part of this patch.

The fundamental building block is the CreateCanonicalLoop that only takes the loop trip count and operates on the logical iteration spaces only. An overloaded CreateCanonicalLoop for using LB, UB, Increment is provided as well, but at least for C++, Clang will need to implement a loop counter to logical induction variable mapping anyway, since iterator overload resolution cannot be done in LLVMFrontend.

As there currently is no user for CreateCanonicalLoop, it is only called from unittests. Similarly, CanonicalLoopInfo::eraseFromParent() is used in my file implementation and might be generally useful for implementing loop-associated constructs, but is not used in this patch itself.

The following non-exhaustive list describes not yet covered items:
 * collapse clause (including non-rectangular and non-perfectly nested); idea is to provide a OpenMPIRBuilder::collapseLoopNest method consuming multiple nested loops and returning a new CanonicalLoopInfo that can be used for loop-associated directives.
 * simarly: ordered clause for DOACROSS loops
 * branch weights
 * Cancellation point (?)
 * AllocaIP
 * break statement (if needed at all)
 * Exceptions (if not completely handled in the front-end)
  * Using it in Clang; this requires implementing at least one loop-associated construct.
 * ...

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D90830
2020-11-09 15:03:32 -06:00
Lucas Prates c2c2cc1360 [ARM][AArch64] Adding Neoverse V1 CPU support
Add support for the Neoverse V1 CPU to the ARM and AArch64 backends.

This is based on patches from Mark Murray and Victor Campos.

Reviewed By: dmgreen

Differential Revision: https://reviews.llvm.org/D90765
2020-11-09 13:15:40 +00:00
Nikita Popov d1fbf39b64 [CaptureTrackingTest] Add missing override marker (NFC) 2020-11-07 11:44:02 +01:00
Nikita Popov d35366bcca [CaptureTracking] Correctly handle multiple uses in one instruction
If the same value is used multiple times in the same instruction,
CaptureTracking may end up reporting the wrong use as being captured,
and/or report the same use as being captured multiple times.

Make sure that all checks take the use operand number into account,
rather than performing unreliable comparisons against the used value.

I'm not sure whether this can cause any problems in practice, but
at least some capture trackers (ArgUsesTracker, AACaptureUseTracker)
do care about which call argument is captured.
2020-11-07 11:31:20 +01:00
Sander de Smalen 5ee9ef8519 [TypeSize] Extend UnivariateLinearPolyBase with getWithIncrement/Decrement methods
This patch adds getWithIncrement/getWithDecrement methods to
ElementCount and TypeSize to allow:

  TypeSize::getFixed(8).getWithIncrement(8)     <=> TypeSize::getFixed(16)
  TypeSize::getFixed(16).getWithDecrement(8)    <=> TypeSize::getFixed(8)
  TypeSize::getScalable(8).getWithIncrement(8)  <=> TypeSize::getScalable(16)
  TypeSize::getScalable(16).getWithDecrement(8) <=> TypeSize::getScalable(8)

This patch implements parts of the POC in D90342.

Reviewed By: ctetreau, dmgreen

Differential Revision: https://reviews.llvm.org/D90713
2020-11-06 09:01:19 +00:00
Giorgis Georgakoudis 700d2417d8 [CodeExtractor] Replace uses of extracted bitcasts in out-of-region lifetime markers
CodeExtractor handles bitcasts in the extracted region that have
lifetime markers users in the outer region as outputs. That
creates unnecessary alloca/reload instructions and extra lifetime
markers. The patch identifies those cases, and replaces uses in
out-of-region lifetime markers with new bitcasts in the outer region.

**Example**
```
define void @foo() {
entry:
  %0 = alloca i32
  br label %extract

extract:
  %1 = bitcast i32* %0 to i8*
  call void @llvm.lifetime.start.p0i8(i64 4, i8* %1)
  call void @use(i32* %0)
  br label %exit

exit:
  call void @use(i32* %0)
  call void @llvm.lifetime.end.p0i8(i64 4, i8* %1)
  ret void
}
```

**Current extraction**
```
define void @foo() {
entry:
  %.loc = alloca i8*, align 8
  %0 = alloca i32, align 4
  br label %codeRepl

codeRepl:                                         ; preds = %entry
  %lt.cast = bitcast i8** %.loc to i8*
  call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast)
  %lt.cast1 = bitcast i32* %0 to i8*
  call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast1)
  call void @foo.extract(i32* %0, i8** %.loc)
  %.reload = load i8*, i8** %.loc, align 8
  call void @llvm.lifetime.end.p0i8(i64 -1, i8* %lt.cast)
  br label %exit

exit:                                             ; preds = %codeRepl
  call void @use(i32* %0)
  call void @llvm.lifetime.end.p0i8(i64 4, i8* %.reload)
  ret void
}

define internal void @foo.extract(i32* %0, i8** %.out) {
newFuncRoot:
  br label %extract

exit.exitStub:                                    ; preds = %extract
  ret void

extract:                                          ; preds = %newFuncRoot
  %1 = bitcast i32* %0 to i8*
  store i8* %1, i8** %.out, align 8
  call void @use(i32* %0)
  br label %exit.exitStub
}
```

**Extraction with patch**
```
define void @foo() {
entry:
  %0 = alloca i32, align 4
  br label %codeRepl

codeRepl:                                         ; preds = %entry
  %lt.cast1 = bitcast i32* %0 to i8*
  call void @llvm.lifetime.start.p0i8(i64 -1, i8* %lt.cast1)
  call void @foo.extract(i32* %0)
  br label %exit

exit:                                             ; preds = %codeRepl
  call void @use(i32* %0)
  %lt.cast = bitcast i32* %0 to i8*
  call void @llvm.lifetime.end.p0i8(i64 4, i8* %lt.cast)
  ret void
}

define internal void @foo.extract(i32* %0) {
newFuncRoot:
  br label %extract

exit.exitStub:                                    ; preds = %extract
  ret void

extract:                                          ; preds = %newFuncRoot
  %1 = bitcast i32* %0 to i8*
  call void @use(i32* %0)
  br label %exit.exitStub
}
```

Reviewed By: vsk

Differential Revision: https://reviews.llvm.org/D90689
2020-11-05 17:01:08 -08:00
Sean Silva e9e2e3107d [STLExtras] Add append_range helper.
This is convenient in a lot of cases, such as when the thing you want
to append is `someReallyLongFunctionName()` that you'd rather not
write twice or assign to a variable for the paired begin/end calls.

Differential Revision: https://reviews.llvm.org/D90894
2020-11-05 16:20:02 -08:00
Reid Kleckner f55247456e Fix bugs in EOL marking in command line tokenizers
Add unit tests for this behavior, since the integration test for
clang-cl did not catch these bugs.

Fixes PR47604

Differential Revision: https://reviews.llvm.org/D90866
2020-11-05 13:01:32 -08:00
Simon Pilgrim 6729b6de1f [KnownBits] Move ValueTracking SREM KnownBits handling to KnownBits::srem. NFCI.
Move the ValueTracking implementation to KnownBits, the SelectionDAG version is more limited so I'm intending to replace that as a separate commit.
2020-11-05 14:58:33 +00:00
Simon Pilgrim e237d56b43 [KnownBits] Move ValueTracking/SelectionDAG UREM KnownBits handling to KnownBits::urem. NFCI.
Both these have the same implementation - so move them to a single KnownBits copy.

GlobalISel will be able to use this as well with minimal effort.
2020-11-05 14:30:59 +00:00
Simon Pilgrim 32bee18b84 [KnownBits] Move ValueTracking/SelectionDAG UDIV KnownBits handling to KnownBits::udiv. NFCI.
Both these have the same implementation - so move them to a single KnownBits copy.

GlobalISel will be able to use this as well with minimal effort.
2020-11-05 13:42:42 +00:00
Simon Pilgrim b25765792b Revert rGbbeb08497ce58 "Revert "[GlobalISel] GISelKnownBits::computeKnownBitsImpl - Replace TargetOpcode::G_MUL handling with the common KnownBits::computeForMul implementation""
Updated the GISel KnownBits tests as KnownBits::computeForMul allows more accurate computation.
2020-11-05 10:39:53 +00:00
Simon Pilgrim 6c1a31858d [UnitTests] Add exhaustive tests for KnownBits shl/lshr/ashr
Thanks to @foad for the suggestion.
2020-11-05 10:13:16 +00:00
Nikita Popov 52b86d35a4 [MemorySSA] Use provided memory location even if instruction is call
If getClobberingMemoryAccess() is called with an explicit
MemoryLocation, but the starting access happens to be a call, the
provided location is currently ignored, and alias analysis queries
will be performed against the call instruction instead. Something
similar happens if the starting access is a load with a MemoryDef.

Change the implementation to not set Q.Inst in the first place if
we want to perform a MemoryLocation-based query, to make sure it
can't be turned into an Instruction-based query along the way...

Additionally, remove the special handling that lifetime.start
intrinsics currently get. They simply report NoAlias for clobbers
between lifetime.start and other calls, but that's obviously not
right if the other call is something like a memset or memcpy. The
default behavior we get from getModRefInfo() will already do the
right thing here.

Differential Revision: https://reviews.llvm.org/D88782
2020-11-04 20:30:22 +01:00
Arthur Eubanks d8f531c42c [NewPM] Don't run before pass instrumentation on required passes
This allows those instrumentation to log when they decide to skip a
pass. This provides extra helpful info for optnone functions and also
will help with opt-bisect.

Have OptNoneInstrumentation print when it skips due to seeing optnone.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D90545
2020-11-04 09:45:10 -08:00
Simon Pilgrim b36cb12a49 Fix gcc braces warning. NFCI.
gcc warns that the EXPECT_TRUE macro isn't surrounded by if() {} - we already do this in other cases in the file.
2020-11-04 15:26:32 +00:00
Sander de Smalen 73b6cb67dc [NFCI] Replace AArch64StackOffset by StackOffset.
This patch replaces the AArch64StackOffset class by the generic one
defined in TypeSize.h.

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D88983
2020-11-04 08:49:00 +00:00
Hans Wennborg 1d3cd7172b Fix GCC error: specialization of 'template<class LeafTy> struct llvm::LinearPolyBaseTypeTraits' in different namespace 2020-11-03 16:55:32 +01:00
Jameson Nash a0ad066ce4 make the AsmPrinterHandler array public
This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of handlers already existed, this just cleans up the code
so that it can be exposed publically.

Replaces https://reviews.llvm.org/D74158

Differential Revision: https://reviews.llvm.org/D89613
2020-11-03 10:02:09 -05:00
Nathan James 97e8da45f9
[ADT] Add SmallVector::pop_back_n
Adds a method called pop_back_n to SmallVector.
This is more readable and less error prone than the alternatives of using
```lang=c++
Vector.resize(Vector.size() - N);
Vector.erase(Vector.end() - N, Vector.end());
for (unsigned I = 0;I<N;++I) Vector.pop_back();
```

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D90576
2020-11-03 14:57:10 +00:00
Sander de Smalen 1667d23e58 [NFCI] Add StackOffset class and base classes for ElementCount, TypeSize.
This patch adds a linear polynomial base class, called LinearPolyBase, which
serves as a base class for StackOffset. It tries to represent a linear
polynomial like:

  c0 * scale0 + c1 * scale1 + ... + cK * scaleK

where the scale is implicit, meaning that only the coefficients are
encoded.

This patch also adds a univariate linear polynomial, which serves as
a base class for ElementCount and TypeSize. This tries to represent a
linear polynomial where only one dimension can be set at any one time,
i.e. a TypeSize is either fixed-sized, or scalable-sized, but cannot be
a combination of the two.

  class LinearPolyBase
     ^
     |
     +---- class StackOffset  (dimensions = 2 (fixed/scalable), type = int64_t)

  class UnivariateLinearPolyBase
     |
     |
     +---- class LinearPolySize (dimensions = 2 (fixed/scalable))
                  ^
                  |
                  +-------- class ElementCount  (type = unsigned)
                  |
                  |
                  +-------- class TypeSize      (type = uint64_t)

Reviewed By: ctetreau, david-arm

Differential Revision: https://reviews.llvm.org/D88982
2020-11-03 09:41:39 +00:00
Georgii Rymar 1af3cb5424 [llvm-readobj/libObject] - Allow dumping objects that has a broken SHT_SYMTAB_SHNDX section.
Currently it is impossible to create an instance of ELFObjectFile when the
SHT_SYMTAB_SHNDX can't be read. We error out when fail to parse the
SHT_SYMTAB_SHNDX section in the factory method.

This change delays reading of the SHT_SYMTAB_SHNDX section entries,
with it llvm-readobj is now able to work with such inputs.

Differential revision: https://reviews.llvm.org/D89379
2020-11-03 11:30:28 +03:00
Reid Kleckner c0a922b3db Add parallelTransformReduce and parallelForEachError
parallelTransformReduce is modelled on the C++17 pstl API of
std::transform_reduce, except our wrappers do not use execution policy
parameters.

parallelForEachError allows loops that contain potentially failing
operations to propagate errors out of the loop. This was one of the
major challenges I encountered while parallelizing PDB type merging in
LLD. Parallelizing a loop with parallelForEachError is not behavior
preserving: the loop will no longer stop on the first error, it will
continue working and report all errors it encounters in a list.

I plan to use this to propagate errors out of LLD's
coff::TpiSource::remapTpiWithGHashes, which currently stores errors an
error in the TpiSource object.

Differential Revision: https://reviews.llvm.org/D90639
2020-11-02 16:50:14 -08:00
Fangrui Song 491dd2711f [LazyCallGraph] Build SCCs of the reference graph in order
```
// The legacy PM CGPassManager discovers SCCs this way:
for function in the source order
  tarjanSCC(function)

// While the new PM CGSCCPassManager does:
for function in the reversed source order [1]
  discover a reference graph SCC
  build call graph SCCs inside the reference graph SCC
```

In the common cases, reference graph ~= call graph, the new PM order is
undesired because for `a | b | c` (3 independent functions), the new PM will
process them in the reversed order: c, b, a. If `a <-> b <-> c`, we can see
that `-print-after-all` will report the sole SCC as `scc: (c, b, a)`.

This patch corrects the iteration order. The discovered SCC order will match
the legacy PM in the common cases.

For some tests (`Transforms/Inline/cgscc-*.ll` and
`unittests/Analysis/CGSCCPassManagerTest.cpp`), the behaviors are dependent on
the SCC discovery order and there are too many check lines for the particular
order.  This patch simply reverses the function order to avoid changing too many
check lines.

Differential Revision: https://reviews.llvm.org/D90566
2020-11-02 13:22:42 -08:00
Fangrui Song 395c8bed64 [MC] Make MCStreamer aware of AsmParser's StartTokLoc
A SMLoc allows MCStreamer to report location-aware diagnostics, which
were previously done by adding SMLoc to various methods (e.g. emit*) in an ad-hoc way.

Since the file:line is most important, the column is less important and
the start token location suffices in many cases, this patch reverts
b7e7131af2

```
// old
symbol-binding-changed.s:6:8: error: local changed binding to STB_GLOBAL
.globl local
       ^
// new
symbol-binding-changed.s:6:1: error: local changed binding to STB_GLOBAL
.globl local
^
```

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D90511
2020-11-02 12:32:07 -08:00
Duncan P. N. Exon Smith c17da8676a Support: Avoid std::tie in Support/FileSystem/UniqueID.h, NFC
Running `-fsyntax-only` on UniqueID.h is 2x faster with this patch
(which avoids calling `std::tie` for `operator<`).  Since the transitive
includers of this file will go up as `FileEntryRef` gets used in more
places, avoid that compile-time hit.  This is a follow-up to
23ed570af1 (suggested by Reid Kleckner).

Also drop the `<tuple>` include from FileSystem.h (which was vestigal
from before UniqueID.h was split out).

Differential Revision: https://reviews.llvm.org/D90471
2020-11-02 13:26:15 -05:00
Arthur Eubanks 5c31b8b94f Revert "Use uint64_t for branch weights instead of uint32_t"
This reverts commit 10f2a0d662.

More uint64_t overflows.
2020-10-31 00:25:32 -07:00
Arthur Eubanks 2e31727a88 [NFC] Clean up PassBuilder
Make DebugLogging a member variable so that users of PassBuilder don't
need to pass it around so much.

Move call to TargetMachine::registerPassBuilderCallbacks() within
PassBuilder so users don't need to remember to call it.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D90437
2020-10-30 10:03:59 -07:00
Arthur Eubanks 10f2a0d662 Use uint64_t for branch weights instead of uint32_t
CallInst::updateProfWeight() creates branch_weights with i64 instead of i32.
To be more consistent everywhere and remove lots of casts from uint64_t
to uint32_t, use i64 for branch_weights.

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D88609
2020-10-30 10:03:46 -07:00
Nathan James cf8d19f4fb
[ADT] Add methods to SmallString for efficient concatenation
A common pattern when using SmallString is to repeatedly call append to build a larger string.
The issue here is the optimizer can't see through this and often has to check there is enough space in the storage for each string you try to append.
This results in lots of conditional branches and potentially multiple calls to grow needing to be emitted if the buffer wasn't large enough.
By taking an initializer_list of StringRefs, SmallString can preallocate the storage it needs for all of the StringRefs which only need to grow one time at most, then use a fast path of copying all the strings into its storage knowing there is guaranteed to be enough capacity.
By using StringRefs, this also means you can append different string like types in one go as they will all be implicitly converted to a StringRef.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D90386
2020-10-30 10:07:40 +00:00
Fangrui Song b7e7131af2 [MC] Add SMLoc to MCStreamer::emitSymbolAttribute and report changed binding warnings/errors for ELF 2020-10-29 19:43:11 -07:00
Adam Balogh 184eb4fa4f [ADT] Fix for ImmutableMapRef
The `Root` member of `ImmutableMapRef` was changed recently from a plain
pointer to `IntrusiveRefCntPtr`. However, the `Profile` member function
was not adjusted. This results in comilation error whenever the
`Profile` method is used on an `ImmutableMapRef`. This patch fixes this
issue and also adds unit tests for `ImmutableMapRef`.

Differential Revision: https://reviews.llvm.org/D89486
2020-10-29 13:19:51 +01:00
Florian Hahn 88d6421e4c [SCEV] Match 'zext (trunc A to iB) to iY' as URem.
URem operations with constant power-of-2 second operands are modeled as
such. This patch on its own has very little impact (e.g. no changes in
CodeGen for MultiSource/SPEC2000/SPEC2006 on X86 -O3 -flto), but I'll
soon post follow-up patches that make use of it to more accurately
determine the trip multiple.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D89821
2020-10-29 10:46:52 +00:00
River Riddle 1095419b10 [llvm][StringExtras] Add a fail-able version of `fromHex`
This revision adds a fail-able/checked version of `fromHex` that fails when the input string contains a non-hex character. This removes the need for users to have a separate check for if the string contains all hex digits. This becomes very costly for large hex strings given that checking if a string contains only hex digits is effectively the same as just converting it in the first place.

Context: In MLIR we use hex strings to represent very large constants in the textual format of the IR. These changes lead to a large decrease in compile time when parsing these constants (2 seconds -> 1 second).

Differential Revision: https://reviews.llvm.org/D90265
2020-10-28 16:58:06 -07:00
Adrian Prantl 0b2b50a5d2 [DebugInfo] Expose Fortran array debug info attributes through DIBuilder.
The support of a few debug info attributes specifically for Fortran
arrays have been added to LLVM recently, but there's no way to take
advantage of them through DIBuilder. This patch extends
DIBuilder::createArrayType to enable the settings of those attributes.

Patch by Chih-Ping Chen!

Differential Review: https://reviews.llvm.org/D90323
2020-10-28 13:13:35 -07:00
Alok Kumar Sharma a6dd01afa3 [DebugInfo] Support for DW_TAG_generic_subrange
This is needed to support fortran assumed rank arrays which
have runtime rank.

  Summary:
Fortran assumed rank arrays have dynamic rank. DWARF TAG
DW_TAG_generic_subrange is needed to support that.

  Testing:
unit test cases added (hand-written)
check llvm
check debug-info

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D89218
2020-10-29 01:34:15 +05:30
Max Kazantsev 5ef84688fb Re-enable "[SCEV] Prove implications of different type via truncation"
When we need to prove implication of expressions of different type width,
the default strategy is to widen everything to wider type and prove in this
type. This does not interact well with AddRecs with negative steps and
unsigned predicates: such AddRec will likely not have a `nuw` flag, and its
`zext` to wider type will not be an AddRec. In contraty, `trunc` of an AddRec
in some cases can easily be proved to be an `AddRec` too.

This patch introduces an alternative way to handling implications of different
type widths. If we can prove that wider type values actually fit in the narrow type,
we truncate them and prove the implication in narrow type.

The return was due to revert of underlying patch that this one depends on.

Unit test temporarily disabled because the required logic in SCEV is switched
off due to compile time reasons.

Differential Revision: https://reviews.llvm.org/D89548
2020-10-28 16:02:14 +07:00
Mitch Phillips ae76729a01 Revert "[DebugInfo] Expose Fortran array debug info attributes through DIBuilder."
This reverts commit 5b3bf8b453.

This caused a regression in the ASan buildbot. See comments at
https://reviews.llvm.org/D89817 for more information.
2020-10-27 20:50:51 -07:00
Mitch Phillips 481e002584 Revert "[ADT] Fix for ImmutableMapRef"
This reverts commit a6336eab0c.

This commit broke check-llvm under ASan:

See http://lab.llvm.org:8011/#/builders/5/builds/446 for more details.
2020-10-27 20:50:46 -07:00
Sam McCall 1a1aad9156 [ADT] Fix accidental pointer comparison in test 2020-10-27 18:11:45 +01:00
Nico Weber 2a4e704c92 Revert "Use uint64_t for branch weights instead of uint32_t"
This reverts commit e5766f25c6.
Makes clang assert when building Chromium, see https://crbug.com/1142813
for a repro.
2020-10-27 09:26:21 -04:00
Alex Richardson 565f4e72da [ValueTracking] Add more tests for alignment assume bundles
I noticed that alignment was no longer inferred as well after I last merged
our CHERI fork from upstream. I opened this review before seeing that D88669
already fixes the same problem, so this commit simply adds the new test that
I added as part of this change.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D89830
2020-10-27 12:16:45 +00:00
Arthur Eubanks e5766f25c6 Use uint64_t for branch weights instead of uint32_t
CallInst::updateProfWeight() creates branch_weights with i64 instead of i32.
To be more consistent everywhere and remove lots of casts from uint64_t
to uint32_t, use i64 for branch_weights.

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D88609
2020-10-26 20:24:04 -07:00
Adrian Prantl 5b3bf8b453 [DebugInfo] Expose Fortran array debug info attributes through DIBuilder.
The support of a few debug info attributes specifically for Fortran
arrays have been added to LLVM recently, but there's no way to take
advantage of them through DIBuilder. This patch extends
DIBuilder::createArrayType to enable the settings of those attributes.

Patch by Chih-Ping Chen!

Differential Revision: https://reviews.llvm.org/D89817
2020-10-26 16:23:36 -07:00
Paul C. Anagnostopoulos 26e2e9f2de [TableGen] [tests] Change integer ranges to use new '...' punctuation
Differential Revision: https://reviews.llvm.org/D90057
2020-10-26 10:47:29 -04:00
Simon Pilgrim b481e00bf4 Fix some signed/unsigned comparison gcc warnings from D87930 2020-10-24 12:51:51 +01:00
Simon Pilgrim ce356e1546 [DAG] Add BuildVectorSDNode::getRepeatedSequence helper to recognise multi-element splat patterns
Replace the X86 specific isSplatZeroExtended helper with a generic BuildVectorSDNode method.

I've just used this to simplify the X86ISD::BROADCASTM lowering so far (and remove isSplatZeroExtended), but we should be able to use this in more places to lower to complex broadcast patterns.

Differential Revision: https://reviews.llvm.org/D87930
2020-10-24 12:23:09 +01:00
Nikita Popov d09c592142 [BasicAA] Fix caching in the presence of phi cycles
Any time we insert a block into VisitedPhiBBs, previously cached
values may no longer be valid for the recursive alias queries. As
such, perform them using an empty AAQueryInfo.

Note that if we recurse to the same phi, the block will already
be inserted, so we reuse the old AAQueryInfo, and thus still
protect against infinite recursion.

This problem can appear with with an without BatchAA, but is more
likely to occur with BatchAA, as more values are cached.

Differential Revision: https://reviews.llvm.org/D90066
2020-10-24 09:58:02 +02:00
David Blaikie 0ec5baa132 llvm-dwarfdump: Support verbose printing DW_OP_convert to print the CU local offset before the resolved absolute offset 2020-10-23 18:50:15 -07:00
Michael Liao 9497e2e7d8 Fix shared build. NFC. 2020-10-23 15:53:05 -04:00
Nikita Popov 1b65a51af8 [BasicAA] Add additional phi cycle test (NFC)
This is a variation of the BatchAA problem that also applies
without BatchAA. We may have a cached result from earlier in
the same query.
2020-10-23 20:31:20 +02:00
vpykhtin 00255f4192 [AMDGPU] Fix access beyond the end of the basic block in execMayBeModifiedBeforeAnyUse.
I was wrong in thinking that MRI.use_instructions return unique instructions and mislead Jay in his previous patch D64393.

First loop counted more instructions than it was in reality and the second loop went beyond the basic block with that counter.

I used Jay's previous code that relied on MRI.use_operands to constrain the number of instructions to check among.
modifiesRegister is inlined to reduce the number of passes over instruction operands and added assert on BB end boundary.

Differential Revision: https://reviews.llvm.org/D89386
2020-10-23 19:17:48 +03:00
Alexander Shaposhnikov 27e11d7120 [MC] Adjust StringTableBuilder for linked Mach-O binaries
LD64 emits string tables which start with a space and a zero byte.
This diff adjusts StringTableBuilder for linked Mach-O binaries to match LD64's behavior.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D89561
2020-10-22 19:19:41 -07:00
Jay Foad 922285abec [PatternMatch] Add new FP matchers. NFC.
This adds matchers m_NonNaN, m_NonInf, m_Finite and m_NonZeroFP as well
as generic support for binding the matched value to an APFloat.

I tried to follow the existing convention of using an FP suffix for
predicates like zero and non-zero, which could be confused with the
integer versions, but not for predicates which are clearly already
FP-specific.

Differential Revision: https://reviews.llvm.org/D89038
2020-10-22 19:43:12 +01:00
Nikita Popov 32b6e9a450 [DomTree] Accept Value as Def (NFC)
Non-instruction defs like arguments, constants or global values
always dominate all instructions/uses inside the function. This
case currently needs to be treated separately by the caller, see
https://reviews.llvm.org/D89623#inline-832818 for an example.

This patch makes the dominator tree APIs accept a Value instead of
an Instruction and always returns true for the non-Instruction case.

A complication here is that BasicBlocks are also Values. For that
reason we can't support the dominates(Value *, BasicBlock *)
variant, as it would conflict with dominates(BasicBlock *, BasicBlock *),
which has different semantics. For the other two APIs we assert
that the passed value is not a BasicBlock.

Differential Revision: https://reviews.llvm.org/D89632
2020-10-22 18:32:03 +02:00
Quentin Colombet ee6abef532 [ValueTracking] Interpret GEPs as a series of adds multiplied by the related scaling factor
Prior to this patch, computeKnownBits would only try to deduce trailing zeros
bits for getelementptrs. This patch adds the logic to treat geps as a series
of add * scaling factor.

Thanks to this patch, using a gep or performing an address computation
directly "by hand" (ptrtoint followed by adds and mul followed by inttoptr)
offers the same computeKnownBits information.

Previously, the "by hand" approach would have given more information.

This is related to https://llvm.org/PR47241.

Differential Revision: https://reviews.llvm.org/D86364
2020-10-21 15:07:04 -07:00
Adam Balogh a6336eab0c [ADT] Fix for ImmutableMapRef
The `Root` member of `ImmutableMapRef` was changed recently from a plain
pointer to `IntrusiveRefCntPtr`. However, the `Profile` member function
was not adjusted. This results in comilation error whenever the
`Profile` method is used on an `ImmutableMapRef`. This patch fixes this
issue and also adds unit tests for `ImmutableMapRef`.

Differential Revision: https://reviews.llvm.org/D89486
2020-10-21 12:13:20 +02:00
David Sherwood f5815105d2 [SVE] Remove reliance on TypeSize comparison operators in unit tests
The EXPECT_XY comparison functions all rely upon using the existing
TypeSize comparison operators, which we are deprecating in favour
of isKnownXY. I've changed all such cases to compare either the known
minimum size or the fixed size.

Differential Revision: https://reviews.llvm.org/D89531
2020-10-21 08:05:55 +01:00
Max Kazantsev bed02fa8b0 Revert "[SCEV] Prove implications of different type via truncation"
This reverts commit 80852a4f2f.

Test is now broken because underlying required patch was also reverted SUDDENLY.
2020-10-21 13:03:46 +07:00
Max Kazantsev 80852a4f2f [SCEV] Prove implications of different type via truncation
When we need to prove implication of expressions of different type width,
the default strategy is to widen everything to wider type and prove in this
type. This does not interact well with AddRecs with negative steps and
unsigned predicates: such AddRec will likely not have a `nuw` flag, and its
`zext` to wider type will not be an AddRec. In contraty, `trunc` of an AddRec
in some cases can easily be proved to be an `AddRec` too.

This patch introduces an alternative way to handling implications of different
type widths. If we can prove that wider type values actually fit in the narrow type,
we truncate them and prove the implication in narrow type.

Differential Revision: https://reviews.llvm.org/D89548
Reviewed By: fhahn
2020-10-21 12:53:22 +07:00
Cyndy Ishida acb33cba6d [llvm] Fix ODRViolations for VersionTuple YAML specializations NFC
It appears for Swift there was confusing errors when trying to parse APINotes, when libAPINotes and libInterfaceStub are linked, they both export symbol
`__ZN4llvm4yaml7yamlizeINS_12VersionTupleEEENSt3__19enable_ifIXsr16has_ScalarTraitsIT_EE5valueEvE4typeERNS0_2IOERS5_bRNS0_12EmptyContextE`, and discovered
same symbol defined within llvm-ifs.

This consolidates the boilerplate into YAMLTraits and defers the specific validation in reading the whole input.
fixes: rdar://problem/70450563

Reviewed By: phosek, dblaikie

Differential Revision: https://reviews.llvm.org/D89764
2020-10-20 18:29:15 -07:00
Georgii Rymar 6487ffafd1 Reland "[yaml2obj][ELF] - Simplify the code that performs sections validation."
This reverts commit 1b589f4d4d and relands the D89463
with the fix: update `MappingTraits<FileFilter>::validate()` in ClangTidyOptions.cpp to
match the new signature (change the return type to "std::string" from "StringRef").

Original commit message:

This:

Changes the return type of MappingTraits<T>>::validate to std::string
instead of StringRef. It allows to create more complex error messages.

It introduces std::vector<std::pair<StringRef, bool>> getEntries():
a new virtual method of Section, which is the base class for all sections.
It returns names of special section specific keys (e.g. "Entries") and flags that says if them exist in a YAML.
The code in validate() uses this list of entries descriptions to generalize validation.
This approach was discussed in the D89039 thread.

Differential revision: https://reviews.llvm.org/D89463
2020-10-20 16:25:33 +03:00
Georgii Rymar 1b589f4d4d Revert "[yaml2obj][ELF] - Simplify the code that performs sections validation."
This reverts commit b9e2b59680.
2020-10-20 15:16:56 +03:00
Georgii Rymar b9e2b59680 [yaml2obj][ELF] - Simplify the code that performs sections validation.
This:
1) Changes the return type of `MappingTraits<T>>::validate` to `std::string`
instead of `StringRef`. It allows to create more complex error messages.

2) It introduces std::vector<std::pair<StringRef, bool>> getEntries():
a new virtual method of Section, which is the base class for all sections.
It returns names of special section specific keys (e.g. "Entries") and flags that
says if them exist in a YAML. The code in validate() uses this list of entries
descriptions to generalize validation.
This approach was discussed in the D89039 thread.

Differential revision: https://reviews.llvm.org/D89463
2020-10-20 11:28:23 +03:00
Nikita Popov ddd0f08318 [BatchAA] Add test for incorrect phi cycle result (NFC)
AA computes the correct result for phi/a1 aliasing, while BatchAA
produces an incorrect result depening on which queries have been
performed beforehand.
2020-10-19 20:53:11 +02:00
Mircea Trofin d454328ea8 [ML] Add final reward logging facility.
Allow logging final rewards. A final reward is logged only once, and is
serialized as all-zero values, except for the last one.

Differential Revision: https://reviews.llvm.org/D89626
2020-10-19 08:44:50 -07:00
Lang Hames 069919c9ba [ORC] Update Symbol Lookup / DefinitionGenerator system.
This patch moves definition generation out from the session lock, instead
running it under a per-dylib generator lock. It also makes the
DefinitionGenerator::tryToGenerate method optionally asynchronous: Generators
are handed an opaque LookupState object which can be captured to stop/restart
the lookup process.

The new scheme provides the following benefits and guarantees:

(1) Queries that do not need to attempt definition generation (because all
    requested symbols matched against existing definitions in the JITDylib)
    can proceed without being blocked by any running definition generators.

(2) Definition generators can capture the LookupState to continue their work
    asynchronously. This allows generators to run for an arbitrary amount of
    time without blocking a thread. Definition generators that do not need to
    run asynchronously can return without capturing the LookupState to eliminate
    unnecessary recursion and improve lookup performance.

(3) Definition generators still do not need to worry about concurrency or
    re-entrance: Since they are still run under a (per-dylib) lock, generators
    will never be re-entered concurrently, or given overlapping symbol sets to
    generate.

Finally, the new system distinguishes between symbols that are candidates for
generation (generation candidates) and symbols that failed to match for a query
(due to symbol visibility). This fixes a bug where an unresolved symbol could
trigger generation of a duplicate definition for an existing hidden symbol.
2020-10-19 01:59:03 -07:00
Lang Hames 5d2e359ce6 [ORC] Move DefinitionGenerator out of JITDylib.
This will make it easier to implement asynchronous definition generators.
2020-10-19 01:59:03 -07:00
Lang Hames d54c4e3821 [ORC] Move SimpleResourceManager function object inits out of constructor.
MSVC doesn't seem to like capturing references to variables in lambdas passed to
the variable's constructor. This should fix the windows bots that have been
unable to build the new ResourceTracker unit test.
2020-10-19 00:19:46 -07:00
Lang Hames 0aec49c853 [ORC] Add support for resource tracking/removal (removable code).
This patch introduces new APIs to support resource tracking and removal in Orc.
It is intended as a thread-safe generalization of the removeModule concept from
OrcV1.

Clients can now create ResourceTracker objects (using
JITDylib::createResourceTracker) to track resources for each MaterializationUnit
(code, data, aliases, absolute symbols, etc.) added to the JIT. Every
MaterializationUnit will be associated with a ResourceTracker, and
ResourceTrackers can be re-used for multiple MaterializationUnits. Each JITDylib
has a default ResourceTracker that will be used for MaterializationUnits added
to that JITDylib if no ResourceTracker is explicitly specified.

Two operations can be performed on ResourceTrackers: transferTo and remove. The
transferTo operation transfers tracking of the resources to a different
ResourceTracker object, allowing ResourceTrackers to be merged to reduce
administrative overhead (the source tracker is invalidated in the process). The
remove operation removes all resources associated with a ResourceTracker,
including any symbols defined by MaterializationUnits associated with the
tracker, and also invalidates the tracker. These operations are thread safe, and
should work regardless of the the state of the MaterializationUnits. In the case
of resource transfer any existing resources associated with the source tracker
will be transferred to the destination tracker, and all future resources for
those units will be automatically associated with the destination tracker. In
the case of resource removal all already-allocated resources will be
deallocated, any if any program representations associated with the tracker have
not been compiled yet they will be destroyed. If any program representations are
currently being compiled then they will be prevented from completing: their
MaterializationResponsibility will return errors on any attempt to update the
JIT state.

Clients (usually Layer writers) wishing to track resources can implement the
ResourceManager API to receive notifications when ResourceTrackers are
transferred or removed. The MaterializationResponsibility::withResourceKeyDo
method can be used to create associations between the key for a ResourceTracker
and an allocated resource in a thread-safe way.

RTDyldObjectLinkingLayer and ObjectLinkingLayer are updated to use the
ResourceManager API to enable tracking and removal of memory allocated by the
JIT linker.

The new JITDylib::clear method can be used to trigger removal of every
ResourceTracker associated with the JITDylib (note that this will only
remove resources for the JITDylib, it does not run static destructors).

This patch includes unit tests showing basic usage. A follow-up patch will
update the Kaleidoscope and BuildingAJIT tutorial series to OrcV2 and will
use this API to release code associated with anonymous expressions.
2020-10-18 21:02:54 -07:00
Lang Hames 6154c4115c [ORC] Remove OrcV1 APIs.
This removes all legacy layers, legacy utilities, the old Orc C bindings,
OrcMCJITReplacement, and OrcMCJITReplacement regression tests.

ExecutionEngine and MCJIT are not affected by this change.
2020-10-18 21:02:44 -07:00
Hubert Tong f4d8e86dbe [test][NFC] Do ptrdiff_t comparison with signed instead of unsigned constants
... because using unsigned constants for comparing against signed values
is liable to mutate the signed value via conversion to an unsigned type
due to the usual arithmetic conversions.
2020-10-18 12:38:41 -04:00
Mircea Trofin 57d3e9cd9b [NFC][ML] Avoid source of some signed/unsigned warnings in TFUtilsTest 2020-10-17 09:07:02 -07:00
Jameson Nash 4242df1470 Revert "make the AsmPrinterHandler array public"
I messed up one of the tests.
2020-10-16 17:22:07 -04:00
Jameson Nash ac2def2d8d make the AsmPrinterHandler array public
This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of handlers already existed, this just cleans up the code
so that it can be exposed publically.

Differential Revision: https://reviews.llvm.org/D74158
2020-10-16 16:27:31 -04:00
Hans Wennborg 95fb3542e8 Disable DynamicLibraryTests when using LLVM_INTEGRATED_CRT_ALLOC (PR47881) 2020-10-16 16:49:58 +02:00
Roman Lebedev 7ee6c40247
Revert "Reland "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown"" and it's follow-ups
While we haven't encountered an earth-shattering problem with this yet,
by now it is pretty evident that trying to model the ptr->int cast
implicitly leads to having to update every single place that assumed
no such cast could be needed. That is of course the wrong approach.

Let's back this out, and re-attempt with some another approach,
possibly one originally suggested by Eli Friedman in
https://bugs.llvm.org/show_bug.cgi?id=46786#c20
which should hopefully spare us this pain and more.

This reverts commits 1fb6104293,
7324616660,
aaafe350bb,
e92a8e0c74.

I've kept&improved the tests though.
2020-10-14 16:09:18 +03:00
Juneyoung Lee 9b3c2a72e4 [ValueTracking] Use assume's noundef operand bundle
This patch updates `isGuaranteedNotToBeUndefOrPoison` to use `llvm.assume`'s `noundef` operand bundle.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D89219
2020-10-14 20:16:33 +09:00
Rainer Orth 3b956a58f3 Reland "[Support][unittests] Enforce alignment in ConvertUTFTest"
This relands commit 53b3873cf4.  The failure
of `ConvertUTFTest.UTF16WrappersForConvertUTF16ToUTF8String` detected the
first time is fixed.

Differential Revision: https://reviews.llvm.org/D88824
2020-10-14 12:02:27 +02:00
Duncan P. N. Exon Smith f2b7d9f7fa Support: Allow use of MemoryBufferRef with line_iterator
Split out from https://reviews.llvm.org/D66782, use `Optional<MemoryBufferRef>`
in `line_iterator` so you don't need access to a `MemoryBuffer*`.  Follow up
patches in `clang/` will leverage this.

Differential Revision: https://reviews.llvm.org/D89280
2020-10-13 16:43:49 -04:00
Duncan P. N. Exon Smith f087597124 Support: Add operator== for MemoryBufferRef and split out MemoryBufferRef.h
As preparation for changing `LineIterator` to work with `MemoryBufferRef`:

- Add an `operator==` that uses buffer pointer identity to ensure two buffers
  are equivalent.
- Split out `MemoryBufferRef.h`, to avoid polluting `LineIterator.h` includers
  with everything from `MemoryBuffer.h`. This also means moving the
  `MemoryBuffer` constructor to a source file.

Differential Revision: https://reviews.llvm.org/D89279
2020-10-13 16:42:24 -04:00
Konstantin Schwarz 7341123439 [GlobalISel][KnownBits] Early return on out of bound shift amounts
If the known shift amount is bigger than or equal to the bitwidth of the type of the value to be shifted,
the result is target dependent, so don't try to infer any bits.

This fixes a crash we've seen in one of our internal test suites.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D89232
2020-10-12 18:39:19 +02:00
Sam McCall 31a575bbc0 [JSON] Add ObjectMapper::mapOptional to validate optional data.
Currently the idiom for mapping optional fields is:
  ObjectMapper O(Val, P);
  if (!O.map("required1", Out.R1) || !O.map("required2", Out.R2))
    return false;
  O.map("optional1", Out.O1); // ignore result
  return true;

If `optional1` is present but malformed, then we won't detect/report
that error. We may even leave `Out` in an incomplete state while returning true.
Instead, we'd often prefer to ignore `optional1` if it is absent, but otherwise
behave just like map().

Differential Revision: https://reviews.llvm.org/D89128
2020-10-12 12:48:08 +02:00
Alok Kumar Sharma 96bd4d34a2 [DebugInfo] Support for DWARF attribute DW_AT_rank
This patch adds support for DWARF attribute DW_AT_rank.

  Summary:
Fortran assumed rank arrays have dynamic rank. DWARF attribute
DW_AT_rank is needed to support that.

  Testing:
unit test cases added (hand-written)
check llvm
check debug-info

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D89141
2020-10-10 17:51:12 +05:30
Bevin Hansson dd3014f3dc [Fixed Point] Add floating point methods to APFixedPoint.
This adds methods to APFixedPoint for converting to and from
floating point values.

Differential Revision: https://reviews.llvm.org/D85961
2020-10-09 10:27:42 +02:00
Quentin Colombet d421e0484a [KnownBits] Add a sextOrTrunc method
We already offer zextOrTrunc and it seems natural to offer the
same capability for sign extension.

This patch is a preparatory addition useful for future computeKnownBits
developments.

Differential Revision: https://reviews.llvm.org/D88937
2020-10-08 11:33:06 -07:00
Quentin Colombet 9431f8ad2e [KnownBits] Add a computeForMul method
This patch refactors the logic in ValueTracking.cpp so that
computeKnownBitsForMul now uses a helper function from KnownBits.

NFC

Differential Revision: https://reviews.llvm.org/D88935
2020-10-08 11:33:06 -07:00
Quentin Colombet f1f31eb2da [unittests] Add a few tests for computeKnownBits with ranges
These tests make sure that the range information is properly
understood during computeKnownBits analysis.

NFC

Differential Revision: https://reviews.llvm.org/D88934
2020-10-08 11:33:06 -07:00
Max Kazantsev a5ef2e0a1e Return "[SCEV] Prove implicaitons via AddRec start"
The initial version of the patch was reverted because it missed the check that
the predicate being proved is actually guarded by this check on 1st iteration.
If it was not executed on 1st iteration (but possibly executes after that), then
it is incorrect to use reasoning about IV start to prove it.

Added the test where the miscompile was seen. Unfortunately, my attempts
to reduce it with bugpoint did not succeed; it can further be reduced when
we understand how to do it without losing the initial bug's notion.

Returning assuming the miscompiles are now gone.

Differential Revision: https://reviews.llvm.org/D88208
2020-10-08 11:15:35 +07:00
Arthur Eubanks 6dcbea877b [NewPM] Use PassInstrumentation for -verify-each
This removes "VerifyEachPass" parameters from a lot of functions which is nice.

Don't verify after special passes or VerifierPass.

This introduces verification on loop and cgscc passes, verifying the corresponding function/module.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D88764
2020-10-07 19:24:25 -07:00
Nico Weber a4961f0d8a Revert "[Support][unittests] Enforce alignment in ConvertUTFTest"
This reverts commit 53b3873cf4.
Seems to break SupportTests.exe's
ConvertUTFTest.UTF16WrappersForConvertUTF16ToUTF8String
on Windows.
2020-10-07 22:23:08 -04:00
Daniel Sanders 91a98ec11e [json] Provide a means to delegate writing a value to another API
(Based on D87170 by dsanders)

I recently had need to call out to an external API to emit a JSON object as part
of one an LLVM tool was emitting. However, our JSON support didn't provide a way
to delegate part of the JSON output to that API.

Add rawValueBegin() and rawValueEnd() to maintain and check the internal state
while something else is writing to the stream. It's the users responsibility to
ensure that the resulting JSON output is still valid.

Differential Revision: https://reviews.llvm.org/D88902
2020-10-07 18:31:45 +02:00
Sam McCall b953a01b2c Reapply [ADT] function_ref's constructor is unavailable if the argument is not callable.
This reverts commit 281703e67f.

GCC 5.4 bugs are worked around by avoiding use of variable templates.

Differential Revision: https://reviews.llvm.org/D88977
2020-10-07 18:31:12 +02:00
Sam McCall 281703e67f Revert "[ADT] function_ref's constructor is unavailable if the argument is not callable."
This reverts commit 4cae6228d1.

Breaks GCC build:
http://lab.llvm.org:8011/#/builders/8/builds/33/steps/6/logs/stdio
2020-10-07 16:37:13 +02:00
Sam McCall 4cae6228d1 [ADT] function_ref's constructor is unavailable if the argument is not callable.
This allows overload sets containing function_ref arguments to work correctly
Otherwise they're ambiguous as anything "could be" converted to a function_ref.

This matches proposed std::function_ref, absl::function_ref, etc.

Differential Revision: https://reviews.llvm.org/D88901
2020-10-07 16:31:09 +02:00
Rainer Orth 53b3873cf4 [Support][unittests] Enforce alignment in ConvertUTFTest
`LLVM-Unit :: Support/./SupportTests/ConvertUTFTest.ConvertUTF16LittleEndianToUTF8String`
`FAIL`s on Solaris/sparcv9:

In `llvm/lib/Support/ConvertUTFWrapper.cpp` (`convertUTF16ToUTF8String`)
the `SrcBytes` arg is reinterpreted/accessed as `UTF16` (`unsigned short`,
which requires 2-byte alignment on strict-alignment targets like Sparc)
without anything guaranteeing the alignment, so the access yields a
`SIGBUS`.

This patch avoids this by enforcing the required alignment in the callers.

Tested on `sparcv9-sun-solaris2.11`.

Differential Revision: https://reviews.llvm.org/D88824
2020-10-07 09:08:41 +02:00
Simon Pilgrim 3cb8347c94 [APIntTest] Extend extractBits to check 'lshr+trunc' pattern for each case as well.
Noticed while triaging PR47731 that we don't have great coverage for such patterns.
2020-10-06 16:32:40 +01:00
Dávid Bolvanský 86429c4eaf [SimplifyLibCalls] Optimize mempcpy_chk to mempcpy 2020-10-06 17:08:46 +02:00
Max Kazantsev bbb0ee6e34 Revert "[SCEV] Prove implicaitons via AddRec start"
This reverts commit 69acdfe075.

Need to investigate reported miscompiles.
2020-10-06 11:40:14 +07:00
Mircea Trofin 36bb1fb1fe [MLInliner] Factor out logging
Factored out the logging facility, to allow its reuse outside the
inliner.

Differential Revision: https://reviews.llvm.org/D88770
2020-10-05 18:09:17 -07:00
Mircea Trofin b268e24d43 [NFC][regalloc] Separate iteration from AllocationOrder
This separates the two concerns - encapsulation of traversal order; and
iteration.

Differential Revision: https://reviews.llvm.org/D88256
2020-10-05 16:13:18 -07:00
Amara Emerson c2bce848ec [GlobalISel] Fix CSEMIRBuilder silently allowing use-before-def.
If a CSEMIRBuilder query hits the instruction at the current insert point,
move insert point ahead one so that subsequent uses of the builder don't end up with
uses before defs.

This fix also shows that AMDGPU was also affected by this bug often, but got away
with it because it was using a G_IMPLICIT_DEF before the use.

Differential Revision: https://reviews.llvm.org/D88605
2020-10-05 11:00:00 -07:00
Florian Hahn 348d85a6c7 [VPlan] Clean up uses/operands on VPBB deletion.
Update the code responsible for deleting VPBBs and recipes to properly
update users and release operands.

This is another preparation for D84680 & following patches towards
enabling modeling def-use chains in VPlan.
2020-10-05 14:43:52 +01:00
Florian Hahn 357bbaab66 [VPlan] Add VPRecipeBase::toVPUser helper (NFC).
This adds a helper to convert a VPRecipeBase pointer to a VPUser, for
recipes that inherit from VPUser. Once VPRecipeBase directly inherits
from VPUser this helper can be removed.
2020-10-04 19:43:27 +01:00
Florian Hahn f5fe7abe8a [VPlan] Account for removed users in replaceAllUsesWith.
Make sure we do not iterate using an invalid iterator.

Another small fix/step towards traversing the def-use chains in VPlan.
2020-10-04 18:18:58 +01:00
Florian Hahn 82dcd383c4 [VPlan] Properly update users when updating operands.
When updating operands of a VPUser, we also have to adjust the list of
users for the new and old VPValues. This is required once we start
transitioning recipes to become VPValues.
2020-10-03 20:54:58 +01:00
Sjoerd Meijer 8825fec37e [AArch64] Add CPU Cortex-R82
This adds support for -mcpu=cortex-r82. Some more information about this
core can be found here:

https://www.arm.com/products/silicon-ip-cpu/cortex-r/cortex-r82

One note about the system register: that is a bit of a refactoring because of
small differences between v8.4-A AArch64 and v8-R AArch64.

This is based on patches from Mark Murray and Mikhail Maltsev.

Differential Revision: https://reviews.llvm.org/D88660
2020-10-02 12:47:23 +01:00
David Sherwood b8ce6a6756 [SVE][CodeGen] Add new EVT/MVT getFixedSizeInBits() functions
When we know that a particular type is always going to be fixed
width we have so far been writing code like this:

  getSizeInBits().getFixedSize()

Since we are doing this in quite a few places now it seems to make
sense to add a new helper function that allows us to replace
these calls with a single getFixedSizeInBits() call.

Differential Revision: https://reviews.llvm.org/D88649
2020-10-02 07:47:31 +01:00
Max Kazantsev b8ac19cf1c [SCEV] Limited support for unsigned preds in isImpliedViaOperations
The logic there only considers `SLT/SGT` predicates. We can use the same logic
for proving `ULT/UGT` predicates if all involved values are non-negative.

Adding full-scale support for unsigned might be challenging because of code amount,
so we can consider this in the future.

Differential Revision: https://reviews.llvm.org/D88087
Reviewed By: reames
2020-10-02 10:20:57 +07:00
Sanjay Patel 149f5b573c [APFloat] convert SNaN to QNaN in convert() and raise Invalid signal
This is an alternate fix (see D87835) for a bug where a NaN constant
gets wrongly transformed into Infinity via truncation.
In this patch, we uniformly convert any SNaN to QNaN while raising
'invalid op'.
But we don't have a way to directly specify a 32-bit SNaN value in LLVM IR,
so those are always encoded/decoded by calling convert from/to 64-bit hex.

See D88664 for a clang fix needed to allow this change.

Differential Revision: https://reviews.llvm.org/D88238
2020-10-01 14:37:38 -04:00
Max Kazantsev 69acdfe075 [SCEV] Prove implicaitons via AddRec start
If we know that some predicate is true for AddRec and an invariant
(w.r.t. this AddRec's loop), this fact is, in particular, true on the first
iteration. We can try to prove the facts we need using the start value.

The motivating example is proving things like
```
  isImpliedCondOperands(>=, X, 0, {X,+,-1}, 0}
```

Differential Revision: https://reviews.llvm.org/D88208
Reviewed By: reames
2020-10-01 17:09:38 +07:00
Craig Topper b23916504a Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes (bug 34579)
Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes to behave correctly in the case that the size of the significand is a multiple of the width of the integerParts making up the significand.

The patch to IEEEFloat::isSignificandAllOnes fixes bug 34579, and the patch to IEEE:Float:isSignificandAllZeros fixes the unit test "APFloatTest.x87Next" I added here. I have included both in this diff since the changes are very similar.

Patch by Andrew Briand
2020-09-30 16:07:15 -07:00
Florian Hahn d856365470 [VPlan] Change recipes to inherit from VPUser instead of a member var.
Now that VPUser is not inheriting from VPValue, we can take the next
step and turn the recipes that already manage their operands via VPUser
into VPUsers directly. This is another small step towards traversing
def-use chains in VPlan.

This is NFC with respect to the generated code, but makes the interface
more powerful.
2020-09-30 14:39:00 +01:00
Mircea Trofin 6d193ba333 [NFC][regalloc] Unit test for AllocationOrder iteration.
Added unittests. In the process, separated core construction - which just
needs the hits, order, and 'HardHints' values - from construction from
current register allocation state, to simplify testing.

Differential Revision: https://reviews.llvm.org/D88455
2020-09-29 10:48:07 -07:00
Dominik Montada 113114a5da [GlobalISel] fix widenScalarUnmerge if widen type is not a multiple of destination type
Fix creation of illegal unmerge when widen was requested to a type which
is not a multiple of the destination type. E.g. when trying to widen
an s48 unmerge to s64 the existing code would create an illegal unmerge
from s64 to s48.

Instead, create further unmerges to a GCD type, then use this to remerge
these intermediate results to the actual destinations.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D88422
2020-09-29 15:52:20 +02:00
Mikhail Maltsev 07b7a24e3f [unittests] Preserve LD_LIBRARY_PATH in crash recovery test
We need to preserve the LD_LIBRARY_PATH environment variable when
spawning a child process (certain setups rely on non-standard paths
for e.g. libstdc++). In order to achieve this, set
LLVM_CRC_UNIXCRCRETURNCODE in the parent process instead of creating
the child's environment from scratch.

Reviewed By: aganea

Differential Revision: https://reviews.llvm.org/D88308
2020-09-28 17:46:03 +01:00
Juneyoung Lee ba8911d560 [ValueTracking] Fix analyses to update CxtI to be phi's incoming edges' terminators
It was mentioned that D88276 that when a phi node is visited, terminators at their incoming edges should be used for CtxI.
This is a patch that makes two functions (ComputeNumSignBitsImpl, isGuaranteedNotToBeUndefOrPoison) to do so.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D88360
2020-09-28 23:24:20 +09:00
David Sherwood bafdd11326 [SVE] Replace / operator in TypeSize/ElementCount with divideCoefficientBy
After some recent upstream discussion we decided that it was best
to avoid having the / operator for both ElementCount and TypeSize,
since this could give the impression that these classes can be used
in the same way as basic integer integer types. However, division
for scalable types is a bit odd because we are only dividing the
minimum quantity by a value, as opposed to something like:

  (MinSize * Vscale) / SomeValue

This is why when performing division it's important the caller
first establishes whether the operation makes sense, perhaps by
calling isKnownMultipleOf() prior to division. The caller must now
explictly call divideCoefficientBy() on the class to perform the
operation.

Differential Revision: https://reviews.llvm.org/D87700
2020-09-28 08:03:00 +01:00
Juneyoung Lee 1c45220028 [ValueTracking] Check uses of Argument if it is given to isGuaranteedNotToBeUndefOrPoison
This is a patch that allows isGuaranteedNotToBeUndefOrPoison to return more precise result
when an argument is given, by looking through its uses at the entry block (and following blocks as well, if it is checking poison only).

This is useful when there is a function call with noundef arguments at the entry block.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D88207
2020-09-25 08:57:57 +09:00
Reid Kleckner 495a5e94ba Revert "[NFCI][IR] ConstantRangeTest: add basic scaffolding for next-gen precision/correctness testing"
This reverts commit 9bcf7b1c7a.

Breaks build with MSVC.
2020-09-24 16:47:45 -07:00
Vedant Kumar dfc5a9eb57 [Instruction] Add dropLocation and updateLocationAfterHoist helpers
Introduce a helper which can be used to update the debug location of an
Instruction after the instruction is hoisted. This can be used to safely
drop a source location as recommended by the docs.

For more context, see the discussion in https://reviews.llvm.org/D60913.

Differential Revision: https://reviews.llvm.org/D85670
2020-09-24 15:00:04 -07:00
Roman Lebedev 9bcf7b1c7a
[NFCI][IR] ConstantRangeTest: add basic scaffolding for next-gen precision/correctness testing
I have long complained that while we have exhaustive tests
for ConstantRange, they are, uh, not good.

The approach of groking our own constant range
via exhaustive enumeration is, mysterious.

It neither tells us without doubt that the result is
conservatively correct, nor the precise match to the ConstantRange
result tells us that the result is precise.
But yeah, it's fast, i give it that.

In short, there are three things that we need to check:
1. That ConstantRange result is conservatively correct
2. That ConstantRange range is reasonable
3. That ConstantRange result is reasonably precise

So let's not just check the middle one, but all three.

This provides precision test coverage for D88178.
2020-09-25 00:36:42 +03:00
Roman Lebedev 31177949cb
[NFCI][IR] ConstantRangeTest: refactor operation range gatherers
We do the same dance to acquire the "exact" range of an op via
an exhaustive approach in many places.
Let's not invent the wheel each time.
2020-09-25 00:36:41 +03:00
Matt Arsenault e75afc9acf GlobalISel: Use unmerge when copying wide vectors to result registers
Avoid using G_EXTRACT and move towards a more consistent vector
legalization strategy.
2020-09-24 15:19:51 -04:00
Sanjay Patel e34bd1e0b0 [APFloat] prevent NaN morphing into Inf on conversion (PR43907)
We shift the significand right on a truncation, but that needs to be made NaN-safe:
always set at least 1 bit in the significand.
https://llvm.org/PR43907

See D88238 for the likely follow-up (but needs some plumbing fixes before it can proceed).

Differential Revision: https://reviews.llvm.org/D87835
2020-09-24 14:02:19 -04:00
Alexandre Ganea a6a6ccfc4c Fix f5314d15af - [Support] On Unix, let the CrashRecoveryContext return the signal code
This was causing bots to fail: http://green.lab.llvm.org/green/job/clang-stage1-RA/14828/consoleFull#6384962949ba4694-19c4-4d7e-bec5-911270d8a58c
2020-09-24 09:07:22 -04:00
Alexandre Ganea f5314d15af [Support] On Unix, let the CrashRecoveryContext return the signal code
Before this patch, the CrashRecoveryContext was returning -2 upon a signal, like ExecuteAndWait does. This didn't match the behavior on Windows, where the the exception code was returned.

We now return the signal's code, which optionally allows for re-throwing the signal later. Doing so requires all custom handlers to be removed first, through llvm::sys::unregisterHandlers() which we made a public API.

This is part of https://reviews.llvm.org/D70378
2020-09-24 08:21:43 -04:00
Alexandre Ganea 24f510570f [Support] On Windows, ensure abort() can be catched several times in a row with CrashRecoveryContext
Before this patch, the CrashRecoveryContext would only catch the first abort(). Any further calls to abort() inside subsquent CrashRecoveryContexts would not be catched. This is because the Windows CRT removes the abort() handler before calling it.

This is part of https://reviews.llvm.org/D70378
2020-09-24 08:21:42 -04:00
Sanjay Patel b2c46633d1 [APFloat] add tests for convert of NAN; NFC
More coverage for the bug fix proposed in D87835.
2020-09-24 07:43:07 -04:00
Florian Hahn d4ddf63fc4 [SCEV] Use loop guard info when computing the max BE taken count in howFarToZero.
For some expressions, we can use information from loop guards when
we are looking for a maximum. This patch applies information from
loop guards to the expression used to compute the maximum backedge
taken count in howFarToZero. It currently replaces an unknown
expression X with UMin(X, Y), if the loop is guarded by
X ult Y.

This patch is minimal in what conditions it applies, and there
are a few TODOs to generalize.

This partly addresses PR40961. We will also need an update to
LV to address it completely.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D67178
2020-09-24 11:06:55 +01:00
Alexander Belyaev a90d72127a [llvm] Use instead of in IRSimilarityIdentifierTest.cpp. 2020-09-24 11:28:26 +02:00
Mikael Holmen a1217620a8 [unittests] Use std::make_tuple to make some toolchains happy again
My toolchain stopped working (LLVM 8.0, libstdc++ 5.4.0) after 577adda:

06:25:37 ../unittests/Support/Path.cpp:91:7: error: chosen constructor is explicit in copy-initialization
06:25:37       {"", false, false},  {"/", true, true},      {"/foo", true, true},
06:25:37       ^~~~~~~~~~~~~~~~~~
06:25:37 /proj/flexasic/app/llvm/8.0/bin/../lib/gcc/x86_64-unknown-linux-gnu/5.4.0/../../../../include/c++/5.4.0/tuple:479:19: note: explicit constructor declared here
06:25:37         constexpr tuple(_UElements&&... __elements)
06:25:37                   ^

This commit adds explicit calls to std::make_tuple to work around
the problem.
2020-09-24 11:25:36 +02:00
Andrew Litteken b63bfc2030 [IRSim] Adding a basic similarity identifier.
This takes the mapped instructions from the IRInstructionMapper, and
passes it to the Suffix Tree to find the repeated substrings.  Within
each set of repeated substrings, the IRSimilarityCandidates are compared
against one another for structure, and ensuring that the operands in the
instructions are used in the same way.  Each of these structurally
similarity IRSimilarityCandidates are contained in a SimilarityGroup.

Tests checking for identifying identity of structure, different
isomorphic structure, and different
nonisomoprhic structure are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.

Differential Revision: https://reviews.llvm.org/D86972
2020-09-24 02:05:25 -05:00
Andrew Litteken d1aa143aa8 [IRSim] Adding structural comparison to IRSimilarityCandidate.
Just because sequences of instructions are similar to one another,
doesn't mean they are doing the same thing.

This introduces a structural check for the IRSimilarityCandidate that
compares two IRSimilarityCandidates against one another, and in each
instruction creates a mapping between the operands and results, or
checks that the existing mapping is valid.  If this check passes, it
means we have structurally similar IRSimilarityCandidates.

Tests for whether the candidates are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.

Recommit of: b27db2bb68 for Differential
URL.

Differential Revision: https://reviews.llvm.org/D86971
2020-09-23 22:42:30 -05:00
Andrew Litteken 0a8e097e72 Revert "[IRSim] Adding structural comparison to IRSimilarityCandidate."
This reverts commit b27db2bb68.
2020-09-23 22:40:37 -05:00
Andrew Litteken b27db2bb68 [IRSim] Adding structural comparison to IRSimilarityCandidate.
Just because sequences of instructions are similar to one another,
doesn't mean they are doing the same thing.

This introduces a structural check for the IRSimilarityCandidate that
compares two IRSimilarityCandidates against one another, and in each
instruction creates a mapping between the operands and results, or
checks that the existing mapping is valid.  If this check passes, it
means we have structurally similar IRSimilarityCandidates.

Tests for whether the candidates are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
2020-09-23 22:31:12 -05:00
Arthur Eubanks 29aaa18848 Revert "[NewPM] Add callbacks to PassBuilder to run before/after parsing a pass"
This reverts commit 111aa4e366.
2020-09-23 18:43:13 -07:00
Sam McCall fa69b60806 [JSON] Add error reporting to fromJSON and ObjectMapper
Translating between JSON objects and C++ strutctures is common.
From experience in clangd, fromJSON/ObjectMapper work well and save a lot of
code, but aren't adopted elsewhere at least partly due to total lack of error
reporting beyond "ok"/"bad".

The recently-added error model should be rich enough for most applications.
It requires tracking the path within the root object and reporting local
errors at appropriate places.
To do this, we exploit the fact that the call graph of recursive
parse functions mirror the structure of the JSON itself.
The current path is represented as a linked list of segments, each of which is
on the stack as a parameter. Concretely, fromJSON now looks like:
  bool fromJSON(const Value&, T&, Path);

Beyond the signature change, this is reasonably unobtrusive: building
the path segments is mostly handled by ObjectMapper and the vector<T> fromJSON.
However the root caller of fromJSON must now create a Root object to
store the errors, which is a little clunky.

I've added high-level parse<T>(StringRef) -> Expected<T>, but it's not
general enough to be the primary interface I think (at least, not usable in
clangd).

All existing users (mostly just clangd) are updated in this patch,
making this change backwards-compatible is a bit hairy.

Differential Revision: https://reviews.llvm.org/D88103
2020-09-24 01:20:09 +02:00
Sam McCall 38de1c33a8 [JSON] Display errors associated with Paths in context
When an error occurs processing a JSON object, seeing the actual
surrounding data helps. Dumping just the node where the problem
was identified can be too much or too little information.

printErrorContext() shows the error message in its context, as a comment.
JSON values along the path to the broken place are shown in some detail,
the rest of the document is elided. For example:

```
{
  "credentials": [
    {
      "username": /* error: expected string */ 42,
      "password": "secret"
    },
    { ... }
  ]
  "backups": { ... }
}
```

Differential Revision: https://reviews.llvm.org/D88103
2020-09-24 00:34:11 +02:00
Arthur Eubanks 111aa4e366 [NewPM] Add callbacks to PassBuilder to run before/after parsing a pass
This is in preparation for supporting -debugify-each, which adds a debug
info pass before and after each pass.

Switch VerifyEach to use this.

Reviewed By: ychen

Differential Revision: https://reviews.llvm.org/D88107
2020-09-23 15:25:40 -07:00
Arthur Eubanks 6b1ce83a12 [NewPM][CGSCC] Handle newly added functions in updateCGAndAnalysisManagerForPass
This seems to fit the CGSCC updates model better than calling
addNewFunctionInto{Ref,}SCC() on newly created/outlined functions.
Now addNewFunctionInto{Ref,}SCC() are no longer necessary.

However, this doesn't work on newly outlined functions that aren't
referenced by the original function. e.g. if a() was outlined into b()
and c(), but c() is only referenced by b() and not by a(), this will
trigger an assert.

This also fixes an issue I was seeing with newly created functions not
having passes run on them.

Ran check-llvm with expensive checks.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87798
2020-09-23 15:22:18 -07:00
Sam McCall 16619e7139 [JSON] Facility to track position within an object and report errors.
This error model should be rich enough for most applications. It comprises:

- a name for the root object, so the user knows what we're parsing
- a path from the root object to the JSON node most associated with the error
- a local error message

This can be presented as an llvm::Error e.g.
  "expected string at ConfigFile.credentials[0].username"

It's designed to be cheap: Paths are a linked list of lightweight
objects on the stack. No heap allocations unless errors are encountered.

A subsequent commit will make use of this in the JSON-to-object
translation facilities: fromJSON and ObjectMapper.
However it's independent of these and can be used for e.g. validation alone.

Another subsequent commit will support showing the error in its context
within the parsed value.

Differential Revision: https://reviews.llvm.org/D88103
2020-09-24 00:09:09 +02:00
Sam McCall 140b7b6f09 [JSON] Allow emitting comments in json::OStream
This isn't standard JSON, but is a popular extension.
It will be used to show errors in context, rendering pseudo-json for humans.

Differential Revision: https://reviews.llvm.org/D88103
2020-09-23 23:34:57 +02:00
Andrew Litteken 6ada9e516f [IRSim] Adding IRSimilarityCandidate that contains a region of IRInstructionData.
The IRSimilarityCandidate is a container to hold a region of
IRInstructions and offer interfaces for the starting instruction, ending
instruction, parent function, length.  It also assigns a global value
number for each unique instance of a value in the region.

It also contains an interface to compare two IRSimilarity as to whether
they have the same sequence of similar instructions.

Tests for whether the instructions are similar are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.

Recommit of: 4944bb190f

Differential Revision: https://reviews.llvm.org/D86970
2020-09-23 13:43:34 -05:00
Vinicius Tinti 577adda54f [Support/Path] Add path::is_absolute_gnu
Implements IS_ABSOLUTE_PATH from GNU tools.

C++17 is_absolute behavior is different the from the behavior defined by GNU
tools.

According to cppreference.com, C++17 states: "An absolute path is a path
that unambiguously identifies the location of a file without reference
to an additional starting location."

In other words, the rules are:
 1. POSIX style paths with nonempty root directory are absolute.
 2. Windows style paths with nonempty root name and root directory are
    absolute.
 3. No other paths are absolute.

GNU rules are:
 1. Paths starting with a path separator are absolute.
 2. Windows style paths are also absolute if they start with a character
    followed by ':'.
 3. No other paths are absolute.

On Windows style the path "C:\Users\Default" has "C:" as root name and "\"
as root directory.

Hence "C:" on Windows is absolute under GNU rules and not absolute under
C++17 because it has no root directory. Likewise "/" and "\" on Windows are
absolute under GNU and are not absolute under C++17 due to empty root name.

Related to PR46368.

Differential Revision: https://reviews.llvm.org/D87667
2020-09-23 18:01:32 +01:00