Changes

[ARM] Fix a test case typo. NFC.

The test looked for the wrong string, but it happened to match as
it was a substring of the actual output.

This fixes a typo from d8e67c1cccd8fcb62230166caea744592288da17.

[flang] Update tests for opaque pointers

There is still one remaining failure in Lower/forall/character-1.f90.

[flang] Update memcpy intrinsic mangling for opaque pointers

Flang is manually mangling names for memset/memcpy/memmove
intrinsics, so we need to update the mangling to use the opaque
pointer format (p0 instead of p0i8).

[OrcV2Examples] Fix test with opaque pointers

The other two modules now use opaque pointers, so make sure this
one does as well.

[SVE] Remove custom lowering of scalable vector MGATHER & MSCATTER operations.

Differential Revision: https://reviews.llvm.org/D126255

[Docs] Update default in opaque pointer docs (NFC)

Also mention a relevant C API.

[clang-tidy] Remove extra ";" in ModernizeModuleTest.cpp

Without this fix we get

../../clang-tools-extra/unittests/clang-tidy/ModernizeModuleTest.cpp:270:2: error: extra ';' outside of a function is incompatible with C++98 [-Werror,-Wc++98-compat-extra-semi]
};
 ^
1 error generated.

when compiling with -Werror.

[VPlan] Remove dead VPlan-native special case from BranchOnCount (NFC).

After 05776122b682684ad this special case doesn't exist any longer.

Fix llvm.memset semantics description

The description was referring to a ``src`` parameter probably copied over from ``llvm.memcpy``

[mlir][SCF] Add scf.foreach_thread.parallel_insert_slice canonicalization.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D126761

[flang][docs] Document CMake support

One out-of-date section is also deleted.

Differential Revision: https://reviews.llvm.org/D126712

Revert "Drop qualifiers from return types in C (DR423)"

This reverts commit d374b65f2da1bdd3d9a7e9ac8ed4ad5467c882f9.

The changes lose AST fidelity (reported in #55778), but also may be
improperly dropping _Atomic qualifiers. I am rolling the changes back
until I've finished discussions in WG14 about the proper resolution to
DR423.

Revert "cmake: use llvm dir variables for clang/utils/hmaptool"

As discussed on the review, this change breaks the standalone
clang build. When building against an installed LLVM, the
LLVM_TOOLS_BINARY_DIR cmake variable points to the location of
the installed LLVM tools, not to the cmake build directory. This
means that we would end up trying to move hmaptool into something
like /usr/bin as part of the normal build, while this should only
be happening when running an install target.

This reverts commit bf1ab1f0eb9578914343f48096229ecccd0ecf52.

[flang] Add check for conflict of BIND(C) and Parameter attributes

The entity with BIND(C) attribute cannot be a named constant, so the
BIND(C) and parameter attributes are conflicted. Add check for it.

Reviewed By: klausler

Differential Revision: https://reviews.llvm.org/D126654

[libunwind][ci][AIX] Add libunwind to buildbot CI

Summary:
This patch changes scripts to add libunwind CI on AIX. Test config file ibm-libunwind-shared.cfg.in is introduced for testing on AIX.

Reviewed by: ldionne, MaskRay, libunwind, ibc++abi

Differential Revision: https://reviews.llvm.org/D126017

Revert "[clang][AIX] add option mdefault-visibility-export-mapping"

This caused assertions, see comment on the code review:

llvm/clang/lib/AST/Decl.cpp:1510:
clang::LinkageInfo clang::LinkageComputer::getLVForDecl(const clang::NamedDecl *, clang::LVComputationKind):
Assertion `D->getCachedLinkage() == LV.getLinkage()' failed.

> The option mdefault-visibility-export-mapping is created to allow
> mapping default visibility to an explicit shared library export
> (e.g. dllexport). Exactly how and if this is manifested is target
> dependent (since it depends on how they map dllexport in the IR).
>
> Three values are provided for the option:
>
> * none: the default and behavior without the option, no additional export linkage information is created.
> * explicit: add the export for entities with explict default visibility from the source, including RTTI
> * all: add the export for all entities with default visibility
>
> This option is useful for targets which do not export symbols as part of
> their usual default linkage behaviour (e.g. AIX), such targets
> traditionally specified such information in external files (e.g. export
> lists), but this mapping allows them to use the visibility information
> typically used for this purpose on other (e.g. ELF) platforms.
>
> Reviewed By: MaskRay
>
> Differential Revision: https://reviews.llvm.org/D126340

This reverts commit 8c8a2679a20f621994fa904bcfc68775e7345edc.

[mlir] add decompose and generalize to structured transform ops

These ops complement the tiling/padding transformations by transforming
higher-level named structured operations such as depthwise convolutions into
lower-level and/or generic equivalents that are better handled by some
downstream transformations.

Differential Revision: https://reviews.llvm.org/D126698

[PS5] Support r and y specifiers of freebsd_kernel_printf format strings

Revert "unbreak Modules/cxx20-export-import.cpp with LLVM_APPEND_VC_REV after 8c8a2679a20f"

This reverts commit 4463bd0f89181234e0cef982e21de2e96038f873.
8c8a2679a20f was reverted in d42fe9aa8420.

Update more DR status information for C.

This adds new files to track DRs 100-199 and 400-499, but the file
contents are still a work in progress. It also updates the associated
status in the DR tracking page.

[Binary] Remove OffloadBinary from the Objects enumeration

Summary:
We use the beginning and end of this enumeration to determine what is
and isn't an object format. The enumeration for the OffloadBinary was
put here by mistake which led to it being mistakenly classified as an
Object file.

[SVE] Fixed custom lowering of ISD::INSERT_SUBVECTOR.

LowerINSERT_SUBVECTOR emits AArch64ISD::UUNPK## when lowering
scalable vector floating point INSERT_SUBVECTOR. However, these
nodes only make sense for integer types and thus isel patterns do
not exist for floating point, which leads to isel failures.

This patch ensures floating point operands are cast to integer
before the core lowering takes place.

Fixes: #55037

Differential Revision: https://reviews.llvm.org/D126487

[MCParser] Set default alignment value when meeting invalid align

Upon invalid alignment value, still set a default valid alignment value to avoid
hitting later asserts.

Fix #55273

Differential Revision: https://reviews.llvm.org/D125688

[llvm][ModuleInliner] Refactor InlineSizePriority and PriorityInlineOrder

This patch introduces the abstract base class InlinePriority to serve as
the comparison function for the priority queue.  A derived class, such
as SizePriority, may choose to cache the priorities for different
functions for performance reasons.

This design shields the type used for the priority away from classes
outside InlinePriority and classes derived from it.  In turn,
PriorityInlineOrder no longer needs to be a template class.

Reviewed By: kazu

Differential Revision: https://reviews.llvm.org/D126300

[lldb][NFC] Move generic DWARFASTParser code out of Clang-specific code

This patch moves ParseChildArrayInfo out of DWARFASTParserClang in order
to decouple Clang-specific logic from DWARFASTParser.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D114668

Signed-off-by: Luís Ferreira <contact@lsferreira.net>

[gn build] Port f9b8f422e711

Tidy up `pragma comment lib` handling and testing

A bit of historical research shows that over the years:
Commit 99efc036 added `pragma comment lib` support for PS4.
Commit fd4db533 added `pragma comment lib` support for all ELF targets.
Commit 1d16515f reworked dependent-library support for all ELF targets.

The upshot is that some PS4-specific code became dead, and the
testing became somewhat fragmented.  I've removed the dead code and
combined the previous PS4-specific and linux-specific tests for the
diagnostics into one generic ELF test.
Also added a couple of PS5 runs while I was in there.

[libc++][test] Enable some more string_view tests

Some test cases for `ends_with.ptr.pass` and `starts_with.ptr.pass` for
`string_view` are commented out, but work just fine. Uncomment them.

Differential Revision: https://reviews.llvm.org/D126849

[RISCV] Fix an inconsistency with compatible load/store handling

Once we've computed the incoming predecessor state, we should use the same compatibility check with knowledge of MI as we did in phase 2 in order to be consistent across all phases.

Differential Revision: https://reviews.llvm.org/D126574

[libc++] Lets to_chars use header implementation.

This removes the duplicated code from the dylib. Instead the dylib will
call the new functions in the header. Since this code is unneeded it's
removed from the unstable ABI.

Depends on D125704

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D125761

Revert "[llvm][ModuleInliner] Refactor InlineSizePriority and PriorityInlineOrder"

This reverts commit 50de7f1e7787bf327d1d04c4daab97c1c180b58c.

[llvm][ModuleInliner] Refactor InlineSizePriority and PriorityInlineOrder

This patch introduces the abstract base class InlinePriority to serve as
the comparison function for the priority queue.  A derived class, such
as SizePriority, may choose to cache the priorities for different
functions for performance reasons.

This design shields the type used for the priority away from classes
outside InlinePriority and classes derived from it.  In turn,
PriorityInlineOrder no longer needs to be a template class.

Reviewed By: kazu

Differential Revision: https://reviews.llvm.org/D126300

[OpenMP][libomp] Make LIBOMP_CONFIGURED_LIBFLAGS a list instead of string

When configuring llvm with the openmp subproject, the build for the omp
target fails if LIBOMP_CONFIGURED_LIBFLAGS contains more than one item.
LIBOMP_CONFIGURED_LIBFLAGS should be a semicolon-separated list instead
of a string with items separated by spaces.

Differential Revision: https://reviews.llvm.org/D125370

[OpenMP] omp_get_proc_id uses sched_getcpu fallback on FreeBSD 13.1 and above.

Reviewers: jlpeyton, jdoerfert

Reviewed-By: jlpeyton

Differential-Revision: https://reviews.llvm.org/D126408

[lldb][NFC] Move non-clang specific method to the generic DWARF Parser

This patch renames DW_ACCESS_to_AccessType function and move it to the abstract
DWARFASTParser, since there is no clang-specific code there. This is useful for
plugins other than Clang.

Reviewed By: shafik, bulbazord

Differential Revision: https://reviews.llvm.org/D114719

[RISCV] Add test case showing unnecessary extend after i32 smax on rv64. NFC

One of the operands of the smax is a positive value so computeKnownBits
determines the result of the smax must always be positive. This allows
DAG combiner to convert the sign extend to zero extend before type
legalization.

After type legalization the smax is promoted to i64 by sign extending
its inputs and the zero extend becomes an AND instruction. We are unable
to remove the AND at this point and it becomes a pair of shifts or a
zext.w.

The result of smax has as many sign bits as the minimum of its inputs.
Had we kept the sign extend instead of turning it into a zero extend
it would be removed by DAG combiner after type legalization.

[mlir] translate memref.reshape with static shapes but dynamic dims

Prior to this patch, the lowering of memref.reshape operations to the
LLVM dialect failed if the shape argument had a static shape with
dynamic dimensions.  This patch adds the necessary support so that when
the shape argument has dynamic values, the lowering probes the dimension
at runtime to set the size in the `MemRefDescriptor` type.  This patch
also computes the stride for dynamic dimensions by deriving it from the
sizes of the inner dimensions.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D126604

[libc++] Fix typo in comment at __optional_storage_base

Small typo fix(es) for struct definition of __optional_storage_base for
a reference type.

Reviewed By: #libc, jloser, philnik

Differential Revision: https://reviews.llvm.org/D126621

[analyzer][NFC] Add partial specializations for ProgramStateTraits

I'm also hoisting common code from the existing specializations into a
common trait impl to reduce code duplication.

Reviewed By: martong

Differential Revision: https://reviews.llvm.org/D126801

[analyzer][NFC] Uplift checkers after D126801

Reviewed By: martong

Differential Revision: https://reviews.llvm.org/D126802

[llvm][analyzer][NFC] Introduce SFINAE for specializing FoldingSetTraits

Reviewed By: martong

Differential Revision: https://reviews.llvm.org/D126803

[PS5] Classify __m64 as integer, matching PS4 ABI

[PS5] Make passing unions in registers match PS4 ABI

[AMDGPU] gfx11 ds instructions

MC layer support for ds instructions

Contributors:
Piotr Sobczak <Piotr.Sobczak@amd.com>

Patch 14/N for upstreaming of AMDGPU gfx11 architecture.

Depends on D126463

Reviewed By: arsenm, #amdgpu

Differential Revision: https://reviews.llvm.org/D126468

Fix a buglet in remove_dots().

The function promises to canonicalize the path, but neglected to do so
for the root component.

For example, calling remove_dots("/tmp/foo.c", Style::windows_backslash)
resulted in "/tmp\foo.c". Now it produces "\tmp\foo.c".

Also fix FIXME in the corresponding test.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D126412

scan-build-py: Change scripts to explicitly require python3

The "#!" line in all scan-build-py scripts were using just bare
"/usr/bin/python" which according to PEP-0394 can be either python3,
python2 or not exist at all.

E.g in latest debian and ubuntu releases "/usr/bin/python" does not
exist at all by default and user must install python-is-python2 or
python-is-python3 packages to get the bare version less "python"
command.

Until recently (70b06fe8a186 "scan-build-py: Force the opening in utf-8"
changed "libscanbuild") these scripts worked in both python2 and
python3, but now they (rightfully) are python3 only, and broke on
systems where the "python" command means python2.

By changing the "#!" to be "python3" it is not only explicit that the
scripts require python3 it also works on systems where "python" command
is python2 or nonexistent.

Differential Revision: https://reviews.llvm.org/D126804

[SLP]Improve shuffles cost estimation where possible.

Improved/fixed cost modeling for shuffles by providing masks, improved
cost model for non-identity insertelements.

Differential Revision: https://reviews.llvm.org/D115462

[mlir:MultiOpDriver] Don't add ops which are not in the allowed list

In strict mode, only the new inserted operation is allowed to add to the
worklist. Before this change, it would add the users of a replaced op
and it didn't check if the users are allowed to be pushed into the
worklist

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D126899

[AMDGPU] gfx11 vop3 and inherited vop instructions

This patch includes MC layer support for VOP3 encoded instructions and generic VOP support
classes.
Some VOP1 and VOP2 instructions which share an encoding with gfx10 and are using
the AssemblerPredicate = isGFX10Plus are also enabled. That predicate
will be changed to isGFX10Only in a later patch.

Patch 15/N for upstreaming of AMDGPU gfx11 architecture.

Depends on D126468

Reviewed By: dp

Differential Revision: https://reviews.llvm.org/D126475

Adapt IRForTarget::RewriteObjCSelector() for D126689.

With opaque pointers, the LLVM IR expected by this function changed.

[mlir][sparse][bufferization] fix doc on new init operation

The example was still using the -now- removed sparse_tensor.init_tensor.
Also, I made the input operands of the matrix multiplication sparse too
(since it looks a bit strange to multiply two dense matrices into a sparse).

Reviewed By: bixia

Differential Revision: https://reviews.llvm.org/D126897

[GVN] Add test for capture tracking use limit.

Test for capture-tracking-max-uses-to-explore, adjusted in D126236.

[PS5] Apply 'packed' attribute to base classes, matching PS4 ABI

[PS5] Pack non-POD members in packed structs, matching PS4 ABI

[OpenMP][libomp] do not try to dlopen libmemkind on macOS

The memkind library is only available for linux. Calling dlopen here
can also be problematic in a client app that fork'ed.

Differential Revision: https://reviews.llvm.org/D126579

[libc++][test] Fix unused variable warning in string_view tests

In 6423a9f0ec8ba70049ea76e7bcfc9a9d1a54e826, I accidentally thought this was
getting tested, but these variables are unused. Just remove the lines instead of
leaving them commented out.

Differential Revision: https://reviews.llvm.org/D126901

[DAGCombiner][RISCV] Improve computeKnownBits for (smax X, C) where C is non-negative.

If C is non-negative, the result of the smax must also be
non-negative, so all sign bits of the result are 0.

This allows DAGCombiner to remove a zext_inreg in the modified test.
This zext_inreg started as a sext that became zext before type
legalization then was promoted to a zext_inreg.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D126896

[BOLT][NFC] Fix braces in BinaryEmitter

Reviewed By: rafauler

Differential Revision: https://reviews.llvm.org/D126844

[InstCombine] make pattern matching more consistent; NFC

We could go either way on this and several similar matches.
Just matching as a binop is possibly slightly more efficient;
we don't need to re-confirm the opcode of the instruction.

[InstCombine] add tests for mul with low-bit mask operand; NFC

[HLSL] Add WaveActiveCountBits as Langugage builtin function for HLSL

One clang builtins are introduced
 uint WaveActiveCountBits( bool bBit ) as Langugage builtin function for HLSL.

The detail for WaveActiveCountBits is at
https://github.com/microsoft/DirectXShaderCompiler/wiki/Wave-Intrinsics#uint-waveactivecountbits-bool-bbit-

This is only clang part change to make WaveActiveCountBits into AST.
llvm intrinsic for WaveActiveCountBits will be add in separate PR.

Reviewed By: Anastasia

Differential Revision: https://reviews.llvm.org/D126857

[RISCV] Inline one copy of needVSETVLI into the other [NFC]

Calling the non-MI version directly was unsound (as fixed in dcdb0bf2), so remove that version to decrease likelyhood of future mistakes.

Adapt IRForTarget::RewriteObjCConstStrings() for D126689.

With opaque pointers, the LLVM IR expected by this function changed.

[Inline][Remark][NFC] Optionally provide inline context to inline
advisor.

This patch has no functional change, and merely a preparation patch for
main functional change. The motivating use case is to annotate inline
remark pass name with context information (e.g. prelink or postlink,
CGSCC or always-inliner), see D125495 for more details.

Differential Revision: https://reviews.llvm.org/D126824

[mlir] Add integer range inference analysis

This commit defines a dataflow analysis for integer ranges, which
uses a newly-added InferIntRangeInterface to compute the lower and
upper bounds on the results of an operation from the bounds on the
arguments. The range inference is a flow-insensitive dataflow analysis
that can be used to simplify code, such as by statically identifying
bounds checks that cannot fail in order to eliminate them.

The InferIntRangeInterface has one method, inferResultRanges(), which
takes a vector of inferred ranges for each argument to an op
implementing the interface and a callback allowing the implementation
to define the ranges for each result. These ranges are stored as
ConstantIntRanges, which hold the lower and upper bounds for a
value. Bounds are tracked separately for the signed and unsigned
interpretations of a value, which ensures that the impact of
arithmetic overflows is correctly tracked during the analysis.

The commit also adds a -test-int-range-inference pass to test the
analysis until it is integrated into SCCP or otherwise exposed.

Finally, this commit fixes some bugs relating to the handling of
region iteration arguments and terminators in the data flow analysis
framework.

Depends on D124020

Depends on D124021

Reviewed By: rriddle, Mogball

Differential Revision: https://reviews.llvm.org/D124023

[docs] Mention LLVMContext::setOpaquePointers for C++ API

[ELF] Remove support for legacy .zdebug sections

.zdebug is unlikely used any longer: gcc -gz switched from legacy
.zdebug to SHF_COMPRESSED with binutils 2.26 (2016), which has been
several years. clang 14 dropped -gz=zlib-gnu support. According to
Debian Code Search (`gz=zlib-gnu`), no project uses -gz=zlib-gnu.

Remove .zdebug support to (a) simplify code and (b) allow removal of llvm-mc's
--compress-debug-sections=zlib-gnu.

In case the old object file `a.o` uses .zdebug, run `objcopy --decompress-debug-sections a.o`

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D126793

[CaptureTracking] Increase limit and use it for all visited uses.

Currently the MaxUsesToExplore limit only applies to the number of users
per value, not the total number of users to explore.

The current limit of 20 pessimizes IR with opaque pointers in some
cases. Without opaque pointers, we have deeper pointer def-use chains in
general due to extra bitcasts and geps for structs with index 0.

With opaque pointers the def-use chain is not as deep but wider, due to
bitcasts & 0-geps missing.

To improve the situation for opaque pointers, this patch does 2 things:

 1. Apply the limit to the total number of uses visited. From the
    wording in the description of the option it seems like this may be
    the original intention. With the current implementation we could
    still end up walking a lot of uses.
 2. Increase the limit to 100. This is quite arbitrary, but enables
    a good number of additional optimizations.

Those adjustments have a noticeable compile-time impact though. In part
that is likely due to additional transformations (and conversely
the current baseline misses optimizations after switching to opaque
pointers).

This recovers some regressions that showed up after enabling opaque
pointers.

Limit=100:

* NewPM-O3: +0.21%
* NewPM-ReleaseThinLTO: +0.87%
* NewPM-ReleaseLTO-g: +0.46%

https://llvm-compile-time-tracker.com/compare.php?from=2e50ecb2ef4e1da1aeab05bcf66380068e680991&to=7e6fbe519d958d09f32f01d5d44a622f551e2031&stat=instructions

Limit=60:

* NewPM-O3: +0.14%
* NewPM-ReleaseThinLTO: +0.41%
* NewPM-ReleaseLTO-g: +0.21%

https://llvm-compile-time-tracker.com/compare.php?from=aeb19817d66f1a15754163c7f48e01e9ebdd6d45&to=520563fdc146319aae90d06f88d87f2e9e1247b7&stat=instructions

Limit=40:
* NewPM-O3: +0.11%
* NewPM-ReleaseThinLTO: +0.12%
* NewPM-ReleaseLTO-g: +0.09%

https://llvm-compile-time-tracker.com/compare.php?from=aeb19817d66f1a15754163c7f48e01e9ebdd6d45&to=c9182576e9fe3f1c84a71479665aef91a416318c&stat=instructions

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D126236

[RISCV] Add custom isel for (add X, imm) used by load/stores.

If the imm is out of range for an ADDI, we will materialize it in
a register using multiple instructions. If the ADD is used by a
load/store, doPeepholeLoadStoreADDI can try to pull an ADDI from
the constant materialization into the load/store offset. This only
works if the ADD has a single use, otherwise the peephole would have
to rebuild multiple nodes.

This patch instead tries to solve the problem when the add is selected.
We check that the add is only used by loads/stores and if it is
we will select it to (ADDI (ADD X, Imm-Lo12), Lo12). This will enable
the simple case in doPeepholeLoadStoreADDI that can bypass an ADDI
used as a pointer. As a result we can remove the more complicated
peephole from doPeepholeLoadStoreADDI.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D126576

Support warn_unused_result on typedefs

While it's not as robust as using the attribute on enums/classes (the
type information may be lost through a function pointer, a declaration
or use of the underlying type without using the typedef, etc) but I
think there's still value in being able to attribute a typedef and have
all return types written with that typedef pick up the
warn_unused_result behavior.

Specifically I'd like to be able to annotate LLVMErrorRef (a wrapper for
llvm::Error used in the C API - the underlying type is a raw pointer, so
it can't be attributed itself) to reduce the chance of unhandled errors.

Differential Revision: https://reviews.llvm.org/D102122

cmake fill `cmake_args` when cross-compiling external project with non-clang compiler

This makes it possible to crosscompile runtimes with cl.exe on Windows.

An external project is completely misconfigured otherwise because
cmake_args is set only for native builds or builds crosscompiled with
clang.

Differential Revision: https://reviews.llvm.org/D122578
Reviewed By: beanz, compnerd

[AMDGPU] Improve codegen of extractelement/insertelement in some cases

This patch improves the codegen of extractelement and insertelement for vector
containing 8 elements. Before, a dag combine transformation was generating a
sequence of 8 select/cmp.
This patch changes the upper limit for this transformation and the movrel
instruction will eventually be used instead. Extractlement/insertelement for
vectors containing less than 8 elements are unchanged.

Differential Revision: https://reviews.llvm.org/D126389

AMDGPU: Move SpilledReg from MFI to SIRegisterInfo

This isn't the most natural place for it, but it avoids a circular
include dependency in an out of tree patch.

Revert "[mlir] Add integer range inference analysis"

This reverts commit 1350c9887dca5ba80af8e3c1e61b29d6696eb240.

Shared library build is broken with undefined references.

[PS5] Ignore 'packed' on one-byte bitfields, matching PS4

[Clang][OpenMP] Avoid using `IgnoreImpCasts` if possible

This patch removes all `IgnoreImpCasts` in Sema, and only uses it if necessary. If the expression is not of the same type as the pointer value, a cast is inserted.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D126602

Clean "./" from __FILE__ expansion.

This is alternative to https://reviews.llvm.org/D121733
and helps with Clang header modules in which FILE
may expand to "./foo.h" or "foo.h" depending on whether the file was
included directly or not.

Only do this when UseTargetPathSeparator is true, as we are already
changing the path in that case.

Reviewed By: ayzhao

Differential Revision: https://reviews.llvm.org/D126396