219 Commits

Author SHA1 Message Date
Bryan Chan
223307b3dc [AArch64] Implement FP16FML intrinsics
Generate the FP16FML intrinsics into arm_neon.h (AArch64 only for now).
Add two new type modifiers to NeonEmitter to handle the new prototypes.
Define __ARM_FEATURE_FP16FML when +fp16fml is enabled and guard the
intrinsics with the macro in arm_neon.h.

Based on a patch by Gao Yiling.

Differential Revision: https://reviews.llvm.org/D53633

llvm-svn: 345344
2018-10-25 23:47:00 +00:00
Erich Keane
19a8adc9bd Implement Function Multiversioning for Non-ELF Systems.
Similar to how ICC handles CPU-Dispatch on Windows, this patch uses the
resolver function directly to forward the call to the proper function.
This is not nearly as efficient as IFuncs of course, but is still quite
useful for large functions specifically developed for certain
processors.

This is unfortunately still limited to x86, since it depends on
__builtin_cpu_supports and __builtin_cpu_is, which are x86 builtins.

The naming for the resolver/forwarding function for cpu-dispatch was
taken from ICC's implementation, which uses the unmodified name for this
(no mangling additions).  This is possible, since cpu-dispatch uses '.A'
for the 'default' version.

In 'target' multiversioning, this function keeps the '.resolver'
extension in order to keep the default function keeping the default
mangling.

Change-Id: I4731555a39be26c7ad59a2d8fda6fa1a50f73284

Differential Revision: https://reviews.llvm.org/D53586

llvm-svn: 345298
2018-10-25 18:57:19 +00:00
Tim Renouf
632f35d495 Add gfx909 to GPU Arch
Subscribers: jholewinski, cfe-commits

Differential Revision: https://reviews.llvm.org/D53558

llvm-svn: 345198
2018-10-24 21:19:02 +00:00
Konstantin Zhuravlyov
06570954e2 AMDGPU: Handle gfx909 in AMDGPUTargetInfo::initFeatureMap
+ add required tests

llvm-svn: 345181
2018-10-24 19:07:56 +00:00
Yaxun Liu
83b5f35d85 Add gfx904 and gfx906 to GPU Arch
Differential Revision: https://reviews.llvm.org/D53472

llvm-svn: 344996
2018-10-23 02:05:31 +00:00
Craig Topper
9ad1e8a93b [X86] Remove 'rtm' feature from KNL.
I'm unsure if KNL has this feature, but the backend never thought it did, only clang did. The predefined-arch-macros test lost the check for __RTM__ on KNL when it was removed Skylake CPUs in r344117.

I think we want to drop it from KNL for consistency with Skylake anyway regardless of how we got here.

llvm-svn: 344978
2018-10-23 00:15:37 +00:00
Krzysztof Parzyszek
57e6706e56 [Hexagon] Remove support for V4
llvm-svn: 344786
2018-10-19 15:36:45 +00:00
Eli Friedman
39ceea326d [AArch64] Define __ELF__ for aarch64-none-elf and other similar triples.
"aarch64-none-elf" is commonly used for AArch64 baremetal toolchains.

Differential Revision: https://reviews.llvm.org/D53348

llvm-svn: 344710
2018-10-17 21:07:11 +00:00
Simon Atanasyan
db81c7b9c9 [mips] Fix handling of GNUABIN32 environment in a target triple
The `GNUABIN32` environment in a target triple implies using the N32
ABI. This patch adds support for this environment and switches on N32
ABI if necessary.

Patch by Patch by YunQiang Su.

Differential revision: https://reviews.llvm.org/D51464

llvm-svn: 344570
2018-10-15 22:43:23 +00:00
Craig Topper
153b53adfa [X86] Remove FeatureRTM from Skylake processor list
Summary:
There are a LOT of Skylakes and later without TSX-NI. Examples:
- SKL: https://ark.intel.com/products/136863/Intel-Core-i3-8121U-Processor-4M-Cache-up-to-3-20-GHz-
- KBL: https://ark.intel.com/products/97540/Intel-Core-i7-7560U-Processor-4M-Cache-up-to-3-80-GHz-
- KBL-R: https://ark.intel.com/products/149091/Intel-Core-i7-8565U-Processor-8M-Cache-up-to-4-60-GHz-
- CNL: https://ark.intel.com/products/136863/Intel-Core-i3-8121U-Processor-4M-Cache-up-to-3_20-GHz

This feature seems to be present only on high-end desktop and server
chips (I can't find any SKX without). This commit leaves it disabled
for all processors, but can be re-enabled for specific builds with
-mrtm.

Matches https://reviews.llvm.org/D53041

Patch by Thiago Macieira

Reviewers: erichkeane, craig.topper

Reviewed By: craig.topper

Subscribers: lebedev.ri, cfe-commits

Differential Revision: https://reviews.llvm.org/D53042

llvm-svn: 344117
2018-10-10 07:43:45 +00:00
Ali Tamur
bc1cd929bf Introduce code_model macros
Summary:
gcc defines macros such as __code_model_small_ based on the user passed command line flag -mcmodel. clang accepts a flag with the same name and similar effects, but does not generate any macro that the user can use. This cl narrows the gap between gcc and clang behaviour.

However, achieving full compatibility with gcc is not trivial: The set of valid values for mcmodel in gcc and clang are not equal. Also, gcc defines different macros for different architectures. In this cl, we only tackle an easy part of the problem and define the macro only for x64 architecture. When the user does not specify a mcmodel, the macro for small code model is produced, as is the case with gcc.

Reviewers: compnerd, MaskRay

Reviewed By: MaskRay

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D52920

llvm-svn: 344000
2018-10-08 22:25:20 +00:00
Craig Topper
6ad9220067 [X86] Add the movbe instruction intrinsics from icc.
These intrinsics exist in icc. They can be found on the Intel Intrinsics Guide website.

All the backend support is in place to pattern match a load+bswap or a bswap+store pattern to the MOVBE instructions. So we just need to get the frontend to emit the correct IR. The pointer arguments in icc are declared as void so I had to jump through a packed struct to forcing a specific alignment on the load/store. Same trick we use in the unaligned vector load/store intrinsics

Differential Revision: https://reviews.llvm.org/D52586

llvm-svn: 343343
2018-09-28 17:09:51 +00:00
Sam Parker
d476cd304b [ARM] Prevent DSP and SIM32 being set for v6m
My previous change (rL340911) set the two features for architectures
>= 6, which wrongly includes v6m. Now set to >= 6 and not Cortex-M.

Differential Revision: https://reviews.llvm.org/D52644

llvm-svn: 343309
2018-09-28 10:18:02 +00:00
Oliver Stannard
a30b48d020 [ARM/AArch64][v8.5A] Add Armv8.5-A target
This patch allows targetting Armv8.5-A from Clang. Most of the
implementation is in TargetParser, so this is mostly just adding tests.

Patch by Pablo Barrio!

Differential revision: https://reviews.llvm.org/D52491

llvm-svn: 343111
2018-09-26 14:20:29 +00:00
Artem Belevich
44ecb0e3c2 [CUDA] Added basic support for compiling with CUDA-10.0
llvm-svn: 342924
2018-09-24 23:10:44 +00:00
Saleem Abdulrasool
6183c6316d Basic: correct __WINT_TYPE__ on Windows
Windows uses `unsigned short` for `wint_t`.  Correct the type definition as
vended by the compiler.  This type is defined in corecrt.h and is
unconditionally typedef'ed.  cl does not have an equivalent to `__WINT_TYPE__`
which is why this was never detected.

llvm-svn: 342557
2018-09-19 16:18:55 +00:00
Erich Keane
7582222691 Move AESNI generation to Skylake and Goldmont
The instruction set first appeared with Westmere, but not all processors
in that and the next few generations have the instructions. According to
Wikipedia[1], the first generation in which all SKUs have AES
instructions are Skylake and Goldmont. I can't find any Skylake,
Kabylake, Kabylake-R or Cannon Lake currently listed at
https://ark.intel.com that says "Intel® AES New Instructions" "No".

This matches GCC commit
https://gcc.gnu.org/ml/gcc-patches/2018-08/msg01940.html

[1] https://en.wikipedia.org/wiki/AES_instruction_set

Patch By: thiagomacieira
Differential Revision: https://reviews.llvm.org/D51510

llvm-svn: 341862
2018-09-10 21:12:21 +00:00
Sam Parker
96d4872899 [ARM] Set __ARM_FEATURE_SIMD32 for +dsp cores
ARM_FEATURE_DSP is already set for targets with the +dsp feature. In
the backend, this target feature is also used to represent the
availability of the of the instructions that the ACLE guard through
the __ARM_FEATURE_SIMD32 macro. We don't have any cores that
implement one and not the other, so set this macro for cores later
than V6 or for Cortex-M cores that the target parser, or user, reports
that the 'dsp' instructions are supported.

Differential Revision: https://reviews.llvm.org/D51093

llvm-svn: 340911
2018-08-29 10:39:03 +00:00
Hans Wennborg
b4278895a4 Revert r323281 "Adjust MaxAtomicInlineWidth for i386/i486 targets."
As reported on http://lists.llvm.org/pipermail/cfe-dev/2018-August/058760.html,
this broke i386-freebsd11 due to its lack of atomic 64 bit primitives.

While that's not really this commit's fault, let's revert back to the old
behaviour until this can be fixed. This means generating cmpxchg8b etc for i386
and i486 which don't technically support those, but that's been the behaviour
for a long time, so a little longer probably doesn't hurt that much.

> Adjust MaxAtomicInlineWidth for i386/i486 targets.
>
> This is to fix the bug reported in https://bugs.llvm.org/show_bug.cgi?id=34347#c6.
> Currently, all  MaxAtomicInlineWidth of x86-32 targets are set to 64. However,
> i386 doesn't support any cmpxchg related instructions. i486 only supports cmpxchg.
> So in this patch MaxAtomicInlineWidth is reset as follows:
> For i386, the MaxAtomicInlineWidth should be 0 because no cmpxchg is supported.
> For i486, the MaxAtomicInlineWidth should be 32 because it supports cmpxchg.
> For others 32 bits x86 cpu, the MaxAtomicInlineWidth should be 64 because of cmpxchg8b.
>
> Differential Revision: https://reviews.llvm.org/D42154

llvm-svn: 340666
2018-08-24 22:46:33 +00:00
Chandler Carruth
ae0cafece8 [x86/retpoline] Split the LLVM concept of retpolines into separate
subtarget features for indirect calls and indirect branches.

This is in preparation for enabling *only* the call retpolines when
using speculative load hardening.

I've continued to use subtarget features for now as they continue to
seem the best fit given the lack of other retpoline like constructs so
far.

The LLVM side is pretty simple. I'd like to eventually get rid of the
old feature, but not sure what backwards compatibility issues that will
cause.

This does remove the "implies" from requesting an external thunk. This
always seemed somewhat questionable and is now clearly not desirable --
you specify a thunk the same way no matter which set of things are
getting retpolines.

I really want to keep this nicely isolated from end users and just an
LLVM implementation detail, so I've moved the `-mretpoline` flag in
Clang to no longer rely on a specific subtarget feature by that name and
instead to be directly handled. In some ways this is simpler, but in
order to preserve existing behavior I've had to add some fallback code
so that users who relied on merely passing -mretpoline-external-thunk
continue to get the same behavior. We should eventually remove this
I suspect (we have never tested that it works!) but I've not done that
in this patch.

Differential Revision: https://reviews.llvm.org/D51150

llvm-svn: 340515
2018-08-23 06:06:38 +00:00
Stefan Maksimovic
eb63256095 [clang][mips] Set __mips_fpr correctly for -mfpxx
Set __mips_fpr to 0 if o32 ABI is used with either -mfpxx
or none of -mfp32, -mfpxx, -mfp64 being specified.

Introduce additional checks:
-mfpxx is only to be used in conjunction with the o32 ABI.
report an error when incompatible options are provided.

Formerly no errors were raised when combining n32/n64 ABIs
with -mfp32 and -mfpxx.

There are other cases when __mips_fpr should be set to 0
that are not covered, ex. using o32 on a mips64 cpu
which is valid but not supported in the backend as of yet.

Differential Revision: https://reviews.llvm.org/D50557

llvm-svn: 340391
2018-08-22 09:26:25 +00:00
Matt Arsenault
b666e73dd9 AMDGPU: Move target code into TargetParser
llvm-svn: 340292
2018-08-21 16:13:29 +00:00
Matt Arsenault
89e833c662 AMDGPU: Correct errors in device table
llvm-svn: 339934
2018-08-16 20:19:47 +00:00
Matt Arsenault
45bc148093 AMDGPU: Fix enabling denormals by default on pre-VI targets
Fast FMAF is not a sufficient condition to enable denormals.
Before VI, enabling denormals caused F32 instructions to
run at F64 speeds.

llvm-svn: 339278
2018-08-08 17:48:37 +00:00
Matt Arsenault
31c895ecdf AMDGPU: Add builtin for s_dcache_wb
llvm-svn: 339110
2018-08-07 07:49:13 +00:00
Matt Arsenault
24f3924709 AMDGPU: Add builtin for s_dcache_inv_vol
llvm-svn: 339109
2018-08-07 07:49:04 +00:00
Matt Arsenault
c65f966d76 Try to make builtin address space declarations not useless
The way address space declarations for builtins currently work
is nearly useless. The code assumes the address spaces used for
builtins is a confusingly named "target address space" from user
code using __attribute__((address_space(N))) that matches
the builtin declaration. There's no way to use this to declare
a builtin that returns a language specific address space.
The terminology used is highly cofusing since it has nothing
to do with the the address space selected by the target to use
for a language address space.

This feature is essentially unused as-is. AMDGPU and NVPTX
are the only in-tree targets attempting to use this. The AMDGPU
builtins certainly do not behave as intended (i.e. all of the
builtins returning pointers can never compile because the numbered
address space never matches the expected named address space).

The NVPTX builtins are missing tests for some, and the others
seem to rely on an implicit addrspacecast.

Change the used address space for builtins based on a target
hook to allow using a language address space for a builtin.
This allows the same builtin declaration to be used for multiple
languages with similarly purposed address spaces (e.g. the same
AMDGPU builtin can be used in OpenCL and CUDA even though the
constant address spaces are arbitarily different).

This breaks the possibility of using arbitrary numbered
address spaces alongside the named address spaces for builtins.
If this is an issue we probably need to introduce another builtin
declaration character to distinguish language address spaces from
so-called "target address spaces".

llvm-svn: 338707
2018-08-02 12:14:28 +00:00
Sjoerd Meijer
e6e4f3178c [AArch64][ARM] Add Armv8.4-A tests
This adds tests for Armv8.4-A, and also some v8.2 and v8.3 tests that were
missing.

Differential Revision: https://reviews.llvm.org/D50068

llvm-svn: 338525
2018-08-01 12:41:10 +00:00
Fangrui Song
6907ce2f8f Remove trailing space
sed -Ei 's/[[:space:]]+$//' include/**/*.{def,h,td} lib/**/*.{cpp,h}

llvm-svn: 338291
2018-07-30 19:24:48 +00:00
Sanjin Sijaric
56391d6f84 [ARM64] [Windows] Follow MS X86_64 C++ ABI when passing structs
Summary: Microsoft's C++ object model for ARM64 is the same as that for X86_64.
For example, small structs with non-trivial copy constructors or virtual
function tables are passed indirectly.  Currently, they are passed in registers
when compiled with clang.

Reviewers: rnk, mstorsjo, TomTan, haripul, javed.absar

Reviewed By: rnk, mstorsjo

Subscribers: kristof.beyls, chrib, llvm-commits, cfe-commits

Differential Revision: https://reviews.llvm.org/D49770

llvm-svn: 338076
2018-07-26 22:18:28 +00:00
Dan Gohman
df07a35912 [WebAssembly] Change size_t to unsigned long.
Changing it to unsigned long (which is 32-bit on wasm32) makes it the same
type as wasm64 (where unsigned long is 64-bit), which would eliminate the most
common cause for mangled names being different between wasm32 and wasm64. For
example, export lists containing symbol names could now often be the same
between wasm32 and wasm64.

Differential Revision: https://reviews.llvm.org/D40526

llvm-svn: 337783
2018-07-24 00:29:58 +00:00
Erik Pilkington
7adcf292a1 NFC: Add the emacs c++ mode hint "-*- C++ -*-" to the headers that don't have it
https://llvm.org/docs/CodingStandards.html#file-headers

llvm-svn: 337780
2018-07-24 00:07:49 +00:00
Reid Kleckner
dbc390d0c5 [MS] Update _MSVC_LANG values for C++17 and C++2a
Fixes PR38262

llvm-svn: 337715
2018-07-23 17:44:00 +00:00
Erich Keane
3efe00206f Implement cpu_dispatch/cpu_specific Multiversioning
As documented here: https://software.intel.com/en-us/node/682969 and
https://software.intel.com/en-us/node/523346. cpu_dispatch multiversioning
is an ICC feature that provides for function multiversioning.

This feature is implemented with two attributes: First, cpu_specific,
which specifies the individual function versions. Second, cpu_dispatch,
which specifies the location of the resolver function and the list of
resolvable functions.

This is valuable since it provides a mechanism where the resolver's TU
can be specified in one location, and the individual implementions
each in their own translation units.

The goal of this patch is to be source-compatible with ICC, so this
implementation diverges from the ICC implementation in a few ways:
1- Linux x86/64 only: This implementation uses ifuncs in order to
properly dispatch functions. This is is a valuable performance benefit
over the ICC implementation. A future patch will be provided to enable
this feature on Windows, but it will obviously more closely fit ICC's
implementation.
2- CPU Identification functions: ICC uses a set of custom functions to identify
the feature list of the host processor. This patch uses the cpu_supports
functionality in order to better align with 'target' multiversioning.
1- cpu_dispatch function def/decl: ICC's cpu_dispatch requires that the function
marked cpu_dispatch be an empty definition. This patch supports that as well,
however declarations are also permitted, since the linker will solve the
issue of multiple emissions.

Differential Revision: https://reviews.llvm.org/D47474

llvm-svn: 337552
2018-07-20 14:13:28 +00:00
Martin Storsjo
17c0f721b9 [AArch64] Define TARGET_HEADER_BUILTIN
Without it, the new intrinsics became available for all language
variants. This was missed in SVN r337327.

llvm-svn: 337352
2018-07-18 06:15:09 +00:00
Joerg Sonnenberger
b79e61f8b3 Always use __mcount on NetBSD. Some platforms don't provide _mcount.
llvm-svn: 337277
2018-07-17 13:13:34 +00:00
Joerg Sonnenberger
68c0210fa6 By popular demand, switch in64_t on NetBSD/AArch64 and NetBSD/PowerPC64
to long for consistency with other 64bit platforms.

llvm-svn: 337271
2018-07-17 12:33:19 +00:00
Krzysztof Parzyszek
762dee516c [Hexagon] Diagnose intrinsics not supported by selected CPU/HVX
llvm-svn: 336933
2018-07-12 18:54:04 +00:00
Alexander Richardson
742553da13 Use Triple::isMIPS() instead of enumerating all Triples. NFC
Reviewed By: atanasyan

Differential Revision: https://reviews.llvm.org/D48549

llvm-svn: 335495
2018-06-25 16:49:52 +00:00
Sjoerd Meijer
5c4c998a54 [SPIR] Prevent SPIR targets from using half conversion intrinsics
The SPIR target currently allows for half precision floating point types to be
emitted using the LLVM intrinsic functions which convert half types to floats
and doubles. However, this is illegal in SPIR as the only intrinsic allowed by
SPIR is memcpy, as per section 3 of the SPIR specification. Currently this is
leading to an assert being hit in the Clang CodeGen when attempting to emit a
constant or literal _Float16 type in a comparison operation on a SPIR or SPIR64
target. This assert stems from the CodeGen attempting to emit a constant half
value as an integer because the backend has specified that it is using these
half conversion intrinsics (which represents half as i16). This patch prevents
SPIR targets from using these intrinsics by overloading the responsible target
info method, marks SPIR targets as having a legal half type and provides
additional regression testing for the _Float16 type on SPIR targets.

Patch by: Stephen McGroarty

Differential Revision: https://reviews.llvm.org/D48188

llvm-svn: 335111
2018-06-20 09:49:40 +00:00
Yonghong Song
6927cf0c2a bpf: recognize target specific option -mattr=dwarfris in clang
The following is the usage example with clang:
  bash-4.2$ clang -target bpf -O2 -g -c -Xclang -target-feature -Xclang +dwarfris t.c
  bash-4.2$ llvm-objdump -S -d t.o

  t.o:    file format ELF64-BPF

  Disassembly of section .text:
  test:
  ; int test(void) {
       0:       b7 00 00 00 00 00 00 00         r0 = 0
  ; return 0;
         1:       95 00 00 00 00 00 00 00         exit
  bash-4.2$ cat t.c
  int test(void) {
    return 0;
  }
  bash-4.2$

Signed-off-by: Yonghong Song <yhs@fb.com>
llvm-svn: 334839
2018-06-15 15:53:31 +00:00
Benjamin Kramer
ffe60e0403 [Basic] Fix -Wreorder warning
Just use field initializers that don't suffer from this problem

llvm-svn: 334619
2018-06-13 16:45:12 +00:00
Stefan Pintilie
a6ce3fe72b [PowerPC] The __float128 type should only be available on Power9
Diasble the use of the type __float128 for PPC machines older
than Power9.

The use of -mfloat128 for PPC machine older than Power9 will result
in an error.

Differential Revision: https://reviews.llvm.org/D48088

llvm-svn: 334613
2018-06-13 16:05:05 +00:00
Reid Kleckner
89fbd55145 Revert r333791 "Cap "voluntary" vector alignment at 16 for all Darwin platforms."
Adding __attribute__((aligned(32))) to __m256 breaks the implementation
of _mm256_loadu_ps on Windows. On Windows, alignment attributes have
higher precedence than packing attributes.

We also might want to carefully consider the consequences of changing
our vector typedefs, since many users copy them and invent their own
new, non-Intel specific vector type names.

llvm-svn: 333958
2018-06-04 21:39:20 +00:00
John McCall
280c656031 Cap "voluntary" vector alignment at 16 for all Darwin platforms.
This fixes two major problems:
- We were not capping vector alignment as desired on 32-bit ARM.
- We were using different alignments based on the AVX settings on
  Intel, so we did not have a consistent ABI.

This is an ABI break, but we think we can get away with it because
vectors tend to be used mostly in inline code (which is why not having
a consistent ABI has not proven disastrous on Intel).

Intel's AVX types are specified as having 32-byte / 64-byte alignment,
so align them explicitly instead of relying on the base ABI rule.
Note that this sort of attribute is stripped from template arguments
in template substitution, so there's a possibility that code templated
over vectors will produce inadequately-aligned objects.  The right
long-term solution for this is for alignment attributes to be
interpreted as true qualifiers and thus preserved in the canonical type.

llvm-svn: 333791
2018-06-01 21:34:26 +00:00
Daniel Cederman
8cc53aecad [Sparc] Add floating-point register names
Reviewers: jyknight

Reviewed By: jyknight

Subscribers: eraman, fedor.sergeev, jrtc27, cfe-commits

Differential Revision: https://reviews.llvm.org/D47137

llvm-svn: 333510
2018-05-30 06:02:18 +00:00
Bob Wilson
fa84fc916c Support Swift calling convention for PPC64 targets
This adds basic support for the Swift calling convention with PPC64 targets.
Patch provided by Atul Sowani in bug report #37223

llvm-svn: 333316
2018-05-25 21:26:03 +00:00
Gabor Buella
078bb99a90 [x86] invpcid intrinsic
An intrinsic for an old instruction, as described in the Intel SDM.

Reviewers: craig.topper, rnk

Reviewed By: craig.topper, rnk

Differential Revision: https://reviews.llvm.org/D47142

llvm-svn: 333256
2018-05-25 06:34:42 +00:00
Alexander Ivchenko
0fb8c877c4 This patch aims to match the changes introduced
in gcc by https://gcc.gnu.org/ml/gcc-cvs/2018-04/msg00534.html.
The -mibt feature flag is being removed, and the -fcf-protection
option now also defines a CET macro and causes errors when used
on non-X86 targets, while X86 targets no longer check for -mibt
and -mshstk to determine if -fcf-protection is supported. -mshstk
is now used only to determine availability of shadow stack intrinsics.

Comes with an LLVM patch (D46882).

Patch by mike.dvoretsky

Differential Revision: https://reviews.llvm.org/D46881

llvm-svn: 332704
2018-05-18 11:56:21 +00:00
Rainer Orth
877d15b396 [Solaris] Only define _REENTRANT if -pthread
When looking at lib/Basic/Targets/OSTargets.h, I noticed that _REENTRANT is defined
unconditionally on Solaris, unlike all other targets and what either Studio cc (only define
it with -mt) or gcc (only define it with -pthread) do.

This patch follows that lead.

Differential Revision: https://reviews.llvm.org/D41241

llvm-svn: 332343
2018-05-15 11:36:00 +00:00