Commit Graph

117 Commits

Author SHA1 Message Date
Fangrui Song 597dfb3bd5 [Driver] Rename AddGoldPlugin to addLTOOptions. NFC
AddGoldPlugin does more than adding `-plugin path/to/LLVMgold.so`.
It works with lld and GNU ld, and adds other LTO options.
So AddGoldPlugin is no longer a suitable name.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D74591
2020-02-14 08:06:37 -08:00
Fangrui Song 8aa3f507c3 [Driver] Don't pass -plugin LLVMgold.so when the linker is ld.lld
This is does not cover the case when ld is lld (e.g. /usr/bin/ld on
modern FreeBSD systems).
2020-02-07 22:53:14 -08:00
Roland McGrath fdf31ae32d [Fuchsia] Never link in implicit "system dependencies" of sanitizer runtimes
This is never appropriate on Fuchsia and any future needs for
system library dependencies of compiler-supplied runtimes will
be addressed via .deplibs instead of driver hacks.

Patch By: mcgrathr

Differential Revision: https://reviews.llvm.org/D73734
2020-01-30 14:21:23 -08:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Yaxun (Sam) Liu b7e415f37f [HIP] Fix environment variable HIP_DEVICE_LIB_PATH
Currently device lib path set by environment variable HIP_DEVICE_LIB_PATH
does not work due to extra "-L" added to each entry.

This patch fixes that by allowing argument name to be empty in addDirectoryList.

Differential Revision: https://reviews.llvm.org/D73299
2020-01-28 11:27:01 -05:00
Roland McGrath f4261e1121 [Clang] Enable -fsanitize=leak on Fuchsia targets
This required some fixes to the generic code for two issues:

1. -fsanitize=safe-stack is default on x86_64-fuchsia and is *not* incompatible with -fsanitize=leak on Fuchisa
2. -fsanitize=leak and other static-only runtimes must not be omitted under -shared-libsan (which is the default on Fuchsia)

Patch By: mcgrathr

Differential Revision: https://reviews.llvm.org/D73397
2020-01-27 23:37:51 -08:00
Josh Kunz 6551ac7489 [Driver] Make -static-libgcc imply static libunwind
In the GNU toolchain, `-static-libgcc` implies that the unwindlib will
be linked statically. However, when `--unwindlib=libunwind`, this flag is
ignored, and a bare `-lunwind` is added to the linker args.  Unfortunately,
this means that if both `libunwind.so`, and `libunwind.a` are present
in the library path, `libunwind.so` will be chosen in all cases where
`-static` is not set.

This change makes `-static-libgcc` affect the `-l` flag produced by
`--unwindlib=libunwind`. After this patch, providing
`-static-libgcc --unwindlib=libunwind` will cause the driver to explicitly
emit `-l:libunwind.a` to statically link libunwind. For all other cases
it will emit `-l:libunwind.so` matching current behavior with a more
explicit link line.

https://reviews.llvm.org/D70416
2019-11-22 15:33:13 -08:00
Tim Northover 44e5879f0f AArch64: add arm64_32 support to Clang. 2019-11-12 12:45:18 +00:00
Hans Wennborg b1ac1f0071 Revert cdcf58e5af "[RISCV] enable LTO support, pass some options to linker."
This started passing target-features on the linker line, not just for RISCV but
for all targets, leading to error messages in Chromium Android build:

  '+soft-float-abi' is not a recognized feature for this target (ignoring feature)
  '+soft-float-abi' is not a recognized feature for this target (ignoring feature)

See Phabricator review for details.

Reverting until this can be fixed properly.

> Summary:
> 1. enable LTO need to pass target feature and abi to LTO code generation
>    RISCV backend need the target feature to decide which extension used in
>    code generation.
> 2. move getTargetFeatures to CommonArgs.h and add ForLTOPlugin flag
> 3. add general tools::getTargetABI in CommonArgs.h because different target uses different
>    way to get the target ABI.
>
> Patch by Kuan Hsu Chen (khchen)
>
> Reviewers: lenary, lewis-revill, asb, MaskRay
>
> Reviewed By: lenary
>
> Subscribers: hiraditya, dschuff, aheejin, fedor.sergeev, mehdi_amini, inglorion, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, kito-cheng, shiva0217, jrtc27, MaskRay, zzheng, edward-jones, steven_wu, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, cfe-commits
>
> Tags: #clang
>
> Differential Revision: https://reviews.llvm.org/D67409
2019-11-11 10:58:39 +01:00
David Blaikie 8d8f9c2440 [clang] Add -fdebug-default-version for specifying the default DWARF version
This flag decouples specifying the DWARF version from enabling/disabling
DWARF in general (or the gN level - gmlt/limited/standalone, etc) while
still allowing existing -gdwarf-N flags to override this default.

Patch by Caroline Tice!

Differential Revision: https://reviews.llvm.org/D69822
2019-11-07 12:05:58 -08:00
Sam Elliott cdcf58e5af [RISCV] enable LTO support, pass some options to linker.
Summary:
1. enable LTO need to pass target feature and abi to LTO code generation
   RISCV backend need the target feature to decide which extension used in
   code generation.
2. move getTargetFeatures to CommonArgs.h and add ForLTOPlugin flag
3. add general tools::getTargetABI in CommonArgs.h because different target uses different
   way to get the target ABI.

Patch by Kuan Hsu Chen (khchen)

Reviewers: lenary, lewis-revill, asb, MaskRay

Reviewed By: lenary

Subscribers: hiraditya, dschuff, aheejin, fedor.sergeev, mehdi_amini, inglorion, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, kito-cheng, shiva0217, jrtc27, MaskRay, zzheng, edward-jones, steven_wu, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67409

llvm-svn: 374774
2019-10-14 14:00:13 +00:00
Sergey Dmitriev a0d83768f1 [Clang][OpenMP Offload] Add new tool for wrapping offload device binaries
This patch removes the remaining part of the OpenMP offload linker scripts which was used for inserting device binaries into the output linked binary. Device binaries are now inserted into the host binary with a help of the wrapper bit-code file which contains device binaries as data. Wrapper bit-code file is dynamically created by the clang driver with a help of new tool clang-offload-wrapper which takes device binaries as input and produces bit-code file with required contents. Wrapper bit-code is then compiled to an object and resulting object is appended to the host linking by the clang driver.

This is the second part of the patch for eliminating OpenMP linker script (please see https://reviews.llvm.org/D64943).

Differential Revision: https://reviews.llvm.org/D68166

llvm-svn: 374219
2019-10-09 20:42:58 +00:00
Yaxun Liu bc2350a341 [HIP] Fix -save-temps
Currently clang does not save some of the intermediate file generated during device compilation for HIP when -save-temps is specified.

This patch fixes that.

Differential Revision: https://reviews.llvm.org/D68665

llvm-svn: 374198
2019-10-09 18:46:43 +00:00
Cullen Rhodes eae7ed479b [Driver] NFC: Remove duplicate call to getLibGccType
Reviewed By: saugustine

Differential Revision: https://reviews.llvm.org/D68380

llvm-svn: 373712
2019-10-04 08:26:37 +00:00
Sergey Dmitriev 4b343fd84c [Clang][OpenMP Offload] Create start/end symbols for the offloading entry table with a help of a linker
Linker automatically provides __start_<section name> and __stop_<section name> symbols to satisfy unresolved references if <section name> is representable as a C identifier (see https://sourceware.org/binutils/docs/ld/Input-Section-Example.html for details). These symbols indicate the start address and end address of the output section respectively. Therefore, renaming OpenMP offload entries section name from ".omp.offloading_entries" to "omp_offloading_entries" to use this feature.

This is the first part of the patch for eliminating OpenMP linker script (please see https://reviews.llvm.org/D64943).

Differential Revision: https://reviews.llvm.org/D68070

llvm-svn: 373118
2019-09-27 20:00:51 +00:00
Pirama Arumuga Nainar ff49a52cf3 [Driver] Handle default case in refactored addOpenMPRuntime
Summary:
Appease failed builds (due to -Werror and -Wswitch) where OMPRT_Unknown
is not handled in the switch statement (even though it's handled by the
early exit).

This fixes -Wswitch triggered by r371442.

Reviewers: srhines, danalbert, jdoerfert

Subscribers: guansong, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67364

llvm-svn: 371444
2019-09-09 19:52:39 +00:00
Pirama Arumuga Nainar d60ff75b56 [Driver] Add -static-openmp driver option
Summary:
For Gnu, FreeBSD and NetBSD, this option forces linking with the static
OpenMP host runtime (similar to -static-libgcc and -static-libstdcxx).

Android's NDK will start the shared OpenMP runtime in addition to the static
libomp.  In this scenario, the linker will prefer to use the shared library by
default.  Add this option to enable linking with the static libomp.

Reviewers: Hahnfeld, danalbert, srhines, joerg, jdoerfert

Subscribers: guansong, cfe-commits

Tags: #clang

Fixes https://github.com/android-ndk/ndk/issues/1028

Differential Revision: https://reviews.llvm.org/D67200

llvm-svn: 371437
2019-09-09 18:31:41 +00:00
Jonas Devlieghere 2b3d49b610 [Clang] Migrate llvm::make_unique to std::make_unique
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.

Differential revision: https://reviews.llvm.org/D66259

llvm-svn: 368942
2019-08-14 23:04:18 +00:00
Fangrui Song 7dbdc8de18 [Driver] Move LIBRARY_PATH before user inputs
Fixes PR16786

Currently, library paths specified by LIBRARY_PATH are placed after inputs: `inputs LIBRARY_PATH stdlib`
In gcc, the order is: `LIBRARY_PATH inputs stdlib` if not cross compiling.
(On Darwin targets, isCrossCompiling() always returns false.)

This patch changes the behavior to match gcc.

Reviewed By: hfinkel

Differential Revision: https://reviews.llvm.org/D65880

llvm-svn: 368245
2019-08-08 01:55:27 +00:00
Fangrui Song d9b948b6eb Rename F_{None,Text,Append} to OF_{None,Text,Append}. NFC
F_{None,Text,Append} are kept for compatibility since r334221.

llvm-svn: 367800
2019-08-05 05:43:48 +00:00
Petr Hosek 85faa70e04 [Driver] Support for disabling sanitizer runtime linking
This change introduces a pair of -fsanitize-link-runtime and
-fno-sanitize-link-runtime flags which can be used to control linking of
sanitizer runtimes. This is useful in certain environments like kernels
where existing runtime libraries cannot be used.

Differential Revision: https://reviews.llvm.org/D65029

llvm-svn: 367794
2019-08-04 22:24:14 +00:00
Fangrui Song e9dc9c2beb [Driver] Simplify AddLibgcc
llvm-svn: 366013
2019-07-14 07:16:13 +00:00
Fangrui Song c7f9559d65 [Driver] Simplify -lgcc & -lgcc_s
gcc defaults to -shared-libgcc in C++ mode.
Letting getLibGccType() return SharedLibGcc simplifies the logic.

llvm-svn: 366012
2019-07-14 06:46:46 +00:00
Petr Hosek b58561baa5 [Fuchsia] Support multilib for -fsanitize=address and -fno-exceptions
This introduces a support for multilibs to Fuchsia driver. Unlike the
existing multilibs that are used primarily for handling different
architecture variants, we use multilibs to handle different variants
of Clang runtime libraries: -fsanitize=address and -fno-exceptions
are the two we support initially. This replaces the existing support
for sanitized runtimes libraries that was only used by Fuchsia driver
and it also refactors some of the logic to allow sharing between GNU
and Fuchsia drivers.

Differential Revision: https://reviews.llvm.org/D61040

llvm-svn: 359360
2019-04-27 00:25:13 +00:00
George Rimar 36d71da694 Revert the r348352 "[clang] - Simplify tools::SplitDebugName."
This partially reverts the r348352 (https://reviews.llvm.org/D55006)
because of https://bugs.llvm.org/show_bug.cgi?id=41161.

I did not revert the test case file because it passes fine now.

llvm-svn: 357061
2019-03-27 11:00:03 +00:00
Sterling Augustine 6271606969 Add --unwindlib=[libgcc|compiler-rt] to parallel --rtlib= [take 2]
"clang++ hello.cc --rtlib=compiler-rt"

now can works without specifying additional unwind or exception
handling libraries.

This reworked version of the feature no longer modifies today's default
unwind library for compiler-rt: which is nothing. Rather, a user
can specify -DCLANG_DEFAULT_UNWINDLIB=libunwind when configuring
the compiler.

This should address the issues from the previous version.

Update tests for new --unwindlib semantics.

Differential Revision: https://reviews.llvm.org/D59109

llvm-svn: 356508
2019-03-19 20:01:59 +00:00
Nemanja Ivanovic 784cdb439e Fix invocation of Gold plugin with LTO after r355331
The above commit breaks the usage of PGO and LTO when -fprofile-use is
supplied without a path. This patch changes the usage of this argument
to be inline with its use in addPGOAndCoverageFlags().

Differential revision: https://reviews.llvm.org/D59304

llvm-svn: 356111
2019-03-13 23:54:52 +00:00
Petr Hosek 930d46a2ef [Driver] Support object files in addition to static and shared libraries in compiler-rt
This change introduces support for object files in addition to static
and shared libraries which were already supported which requires
changing the type of the argument from boolean to an enum.

Differential Revision: https://reviews.llvm.org/D56044

llvm-svn: 355891
2019-03-12 02:12:48 +00:00
Nico Weber 885b790f89 Remove esan.
It hasn't seen active development in years, and it hasn't reached a
state where it was useful.

Remove the code until someone is interested in working on it again.

Differential Revision: https://reviews.llvm.org/D59133

llvm-svn: 355862
2019-03-11 20:23:40 +00:00
Rong Xu a4a09b2398 [PGO] Clang part of change for context-sensitive PGO (part1)
Part 1 of CSPGO change in Clang. This includes changes in clang options
and calls to llvm PassManager. Tests will be committed in part2.
This change needs the PassManager change in llvm.

Differential Revision: https://reviews.llvm.org/D54176

llvm-svn: 355331
2019-03-04 20:21:31 +00:00
Siva Chandra 3988d5c8fa [Clang Driver] Add support for "-static-pie" argument to the Clang driver.
Summary: This change mimics GCC's support for the "-static-pie" argument.

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58307

llvm-svn: 354502
2019-02-20 19:07:04 +00:00
Sterling Augustine 5be3dbdb08 Rollback unwindlib patch.
llvm-svn: 352524
2019-01-29 18:27:51 +00:00
Sterling Augustine 9490fcc191 Add --unwindlib=[libgcc|compiler-rt] to parallel --rtlib=
Summary:
"clang++ hello.cc --rtlib=compiler-rt"

now works without specifying additional unwind or exception
handling libraries.

Reviewers: rsmith

Subscribers: srhines, dberris, aheejin, llvm-commits

Differential Revision: https://reviews.llvm.org/D57128

llvm-svn: 352404
2019-01-28 18:56:43 +00:00
Petr Hosek 9c178356e0 [Driver] Don't pass default value to getCompilerRTArgString
Using static library is already a default.

Differential Revision: https://reviews.llvm.org/D56043

llvm-svn: 351710
2019-01-21 01:34:09 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

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

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

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Craig Topper 5589738979 [Nios2] Remove Nios2 backend
As mentioned here http://lists.llvm.org/pipermail/llvm-dev/2019-January/129121.html This backend is incomplete and has not been maintained in several months.

Differential Revision: https://reviews.llvm.org/D56690

llvm-svn: 351230
2019-01-15 19:58:36 +00:00
Sterling Augustine b6d0f85daf Properly support -shared-libgcc.
This revision was revied in D55016.

llvm-svn: 350900
2019-01-10 22:25:58 +00:00
Michal Gorny 920936ce5f [Driver] Fix accidentally reversed condition in r349752
llvm-svn: 349754
2018-12-20 13:27:37 +00:00
Michal Gorny 5a409d0e30 Replace getOS() == llvm::Triple::*BSD with isOS*BSD() [NFCI]
Replace multiple comparisons of getOS() value with FreeBSD, NetBSD,
OpenBSD and DragonFly with matching isOS*BSD() methods.  This should
improve the consistency of coding style without changing the behavior.
Direct getOS() comparisons were left whenever used in switch or switch-
like context.

Differential Revision: https://reviews.llvm.org/D55916

llvm-svn: 349752
2018-12-20 13:09:30 +00:00
Alex Lorenz 9b20a99823 [darwin][arm64] use the "cyclone" CPU for Darwin even when `-arch`
is not specified

The -target option allows the user to specify the build target using LLVM
triple. The triple includes the arch, and so the -arch option is redundant.
This should work just as well without the -arch. However, the driver has a bug
in which it doesn't target the "Cyclone" CPU for darwin if -target is used
without -arch. This commit fixes this issue.

rdar://46743182

Differential Revision: https://reviews.llvm.org/D55731

llvm-svn: 349382
2018-12-17 19:30:46 +00:00
George Rimar ab090337c5 [clang] - Simplify tools::SplitDebugName.
This is an updated version of the D54576, which was reverted.

Problem was that SplitDebugName calls the InputInfo::getFilename
which asserts if InputInfo given is not of type Filename:

const char *getFilename() const {
  assert(isFilename() && "Invalid accessor.");
  return Data.Filename;
}
At the same time at that point, it can be of type Nothing and
we need to use getBaseInput(), like original code did.

Differential revision: https://reviews.llvm.org/D55006

llvm-svn: 348352
2018-12-05 11:09:10 +00:00
Jonas Toth 1b2ead17d6 Revert "[clang] - Simplify tools::SplitDebugName."
This reverts commit r347035 as it introduced assertion failures under
certain conditions. More information can be found here:
https://reviews.llvm.org/rL347035

llvm-svn: 347676
2018-11-27 17:28:38 +00:00
Petr Hosek fd6a8abd08 Revert "[Driver] Use --push/pop-state with Sanitizer link deps"
This reverts commit r347413: older versions of ld.gold that are used
by Android don't support --push/pop-state which broke sanitizer bots.

llvm-svn: 347430
2018-11-21 21:59:39 +00:00
Petr Hosek 584d935351 [Driver] Use --push/pop-state with Sanitizer link deps
Sanitizer runtime link deps handling passes --no-as-needed because of
PR15823, but it never undoes it and this flag may affect other libraries
that come later on the link line. To avoid this, wrap Sanitizer link
deps in --push/pop-state.

Differential Revision: https://reviews.llvm.org/D54805

llvm-svn: 347413
2018-11-21 20:33:12 +00:00
George Rimar 9982e3b944 [clang] - Simplify tools::SplitDebugName.
This should be NFC change.

SplitDebugName recently started to accept the `Output` that
can be used to simplify the logic a bit, also it
seems that code in SplitDebugName that uses
OPT_fdebug_compilation_dir is simply dead.

Differential revision: https://reviews.llvm.org/D54576

llvm-svn: 347035
2018-11-16 07:59:24 +00:00
George Rimar 91829eef65 [Clang] - Add '-gsplit-dwarf[=split,=single]' version for '-gsplit-dwarf' option.
The DWARF5 specification says(Appendix F.1):

"The sections that do not require relocation, however, can be
written to the relocatable object (.o) file but ignored by the
linker or they can be written to a separate DWARF object (.dwo)
file that need not be accessed by the linker."

The first part describes a single file split DWARF feature and there
is no way to trigger this behavior atm. 
Fortunately, no many changes are required to keep *.dwo sections
in a .o, the patch does that.

Differential revision: https://reviews.llvm.org/D52296

llvm-svn: 346837
2018-11-14 09:22:16 +00:00
Yaxun Liu 92a04835e4 [HIP] Remove useless sections in linked files
clang-offload-bundler creates __CLANG_OFFLOAD_BUNDLE__* sections in the bundles,
which get into the linked files. These sections are useless after linking. They waste disk
space and cause confusion for clang when directly linked with other object files, therefore
should be removed.

Differential Revision: https://reviews.llvm.org/D54275

llvm-svn: 346536
2018-11-09 18:52:05 +00:00
Petr Hosek 4b9940b50a [Driver] Support sanitized libraries on Fuchsia
When using sanitizers, add <resource_dir>/<target>/lib/<sanitizer>
to the list of library paths to support using sanitized version of
runtime libraries if available.

Differential Revision: https://reviews.llvm.org/D53487

llvm-svn: 345537
2018-10-29 20:37:52 +00:00
Martin Storsjo b547ef2a29 Revert "Reapply: [Driver] Use forward slashes in most linker arguments"
This reverts commit r345370, as it uncovered even more issues in
tests with partial/inconsistent path normalization:
http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/13562
http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/886
http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast/builds/20994

In particular, these tests seem to have failed:
    Clang :: CodeGen/thinlto-diagnostic-handler-remarks-with-hotness.ll
    Clang :: CodeGen/thinlto-multi-module.ll
    Clang :: Driver/cuda-external-tools.cu
    Clang :: Driver/cuda-options.cu
    Clang :: Driver/hip-toolchain-no-rdc.hip
    Clang :: Driver/hip-toolchain-rdc.hip
    Clang :: Driver/openmp-offload-gpu.c

At least the Driver tests could potentially be fixed by extending
the path normalization to even more places, but the issues with the
CodeGen tests are still unknown.

In addition, a number of other tests seem to have been broken in
other clang dependent tools such as clang-tidy and clangd.

llvm-svn: 345372
2018-10-26 08:33:29 +00:00
Martin Storsjo cbd73574e4 Reapply: [Driver] Use forward slashes in most linker arguments
libtool inspects the output of $CC -v to detect what object files and
libraries are linked in by default. When clang is built as a native
windows executable, all paths are formatted with backslashes, and
the backslashes cause each argument to be enclosed in quotes. The
backslashes and quotes break further processing within libtool (which
is implemented in shell script, running in e.g. msys) pretty badly.

Between unix style pathes (that only work in tools that are linked
to the msys runtime, essentially the same as cygwin) and proper windows
style paths (with backslashes, that can easily break shell scripts
and msys environments), the best compromise is to use windows style
paths (starting with e.g. c:) but with forward slashes, which both
msys based tools, shell scripts and native windows executables can
cope with. This incidentally turns out to be the form of paths that
GCC prints out when run with -v on windows as well.

This change potentially makes the output from clang -v a bit more
inconsistent, but it is isn't necessarily very consistent to begin with.

Compared to the previous attempt in SVN r345004, this now does
the same transformation on more paths, hopefully on the right set
of paths so that all tests pass (previously some tests failed, where
path fragments that were required to be identical turned out to
use different path separators in different places). This now also
is done only for non-windows, or cygwin/mingw targets, to preserve
all backslashes for MSVC cases (where the paths can end up e.g. embedded
into PDB files. (The transformation function itself,
llvm::sys::path::convert_to_slash only has an effect when run on windows.)

Differential Revision: https://reviews.llvm.org/D53066

llvm-svn: 345370
2018-10-26 07:01:59 +00:00