Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.

MFC r309126 (by emaste):

  Correct lld llvm-tblgen dependency file name

MFC r309169:

  Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
  and llvm-lto.  The mergeinfo confuses Subversion enormously, and these
  directories will just use the mergeinfo for llvm itself.

MFC r312765:

  Pull in r276136 from upstream llvm trunk (by Wei Mi):

    Use ValueOffsetPair to enhance value reuse during SCEV expansion.

    In D12090, the ExprValueMap was added to reuse existing value during
    SCEV expansion. However, const folding and sext/zext distribution can
    make the reuse still difficult.

    A simplified case is: suppose we know S1 expands to V1 in
    ExprValueMap, and
      S1 = S2 + C_a
      S3 = S2 + C_b
    where C_a and C_b are different SCEVConstants. Then we'd like to
    expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
    helpful when S2 is a complex SCEV expr and S2 has no entry in
    ExprValueMap, which is usually caused by the fact that S3 is
    generated from S1 after const folding.

    In order to do that, we represent ExprValueMap as a mapping from SCEV
    to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
    into the ExprValueMap when we create SCEV for V1. When S3 is
    expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
    C_a} in the map, then expand S3 to V1 - C_a + C_b.

    Differential Revision: https://reviews.llvm.org/D21313

  This should fix assertion failures when building OpenCV >= 3.1.

  PR:		215649

MFC r312831:

  Revert r312765 for now, since it causes assertions when building
  lang/spidermonkey24.

  Reported by:	antoine
  PR:		215649

MFC r316511 (by jhb):

  Add an implementation of __ffssi2() derived from __ffsdi2().

  Newer versions of GCC include an __ffssi2() symbol in libgcc and the
  compiler can emit calls to it in generated code.  This is true for at
  least GCC 6.2 when compiling world for mips and mips64.

  Reviewed by:	jmallett, dim
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D10086

MFC r318601 (by adrian):

  [libcompiler-rt] add bswapdi2/bswapsi2

  This is required for mips gcc 6.3 userland to build/run.

  Reviewed by:	emaste, dim
  Approved by:	emaste
  Differential Revision:	https://reviews.freebsd.org/D10838

MFC r318884 (by emaste):

  lldb: map TRAP_CAP to a trace trap

  In the absense of a more specific handler for TRAP_CAP (generated by
  ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
  trap.

  Example usage (testing the bug in PR219173):

  % proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
  ...
  (lldb) run
  Process 12980 launching
  Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
  Process 12980 stopped
  * thread #1, stop reason = trace
      frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
  ...

  In the future we should have LLDB control the trapcap procctl itself
  (as it does with ASLR), as well as report a specific stop reason.
  This change eliminates an assertion failure from LLDB for now.

MFC r319796:

  Remove a few unneeded files from libllvm, libclang and liblldb.

MFC r319885 (by emaste):

  lld: ELF: Fix ICF crash on absolute symbol relocations.

  If two sections contained relocations to absolute symbols with the same
  value we would crash when trying to access their sections. Add a check that
  both symbols point to sections before accessing their sections, and treat
  absolute symbols as equal if their values are equal.

  Obtained from:	LLD commit r292578

MFC r319918:

  Revert r319796 for now, it can cause undefined references when linking
  in some circumstances.

  Reported by:	Shawn Webb <shawn.webb@hardenedbsd.org>

MFC r319957 (by emaste):

  lld: Add armelf emulation mode

  Obtained from:	LLD r305375

MFC r321369:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 (trunk r308421).  Upstream has branched for the 5.0.0 release,
  which should be in about a month.  Please report bugs and regressions,
  so we can get them into the release.

  Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
  support to build; see UPDATING for more information.

MFC r321420:

  Add a few more object files to liblldb, which should solve errors when
  linking the lldb executable in some cases.  In particular, when the
  -ffunction-sections -fdata-sections options are turned off, or
  ineffective.

  Reported by:	Shawn Webb, Mark Millard

MFC r321433:

  Cleanup stale Options.inc files from the previous libllvm build for
  clang 4.0.0.  Otherwise, these can get included before the two newly
  generated ones (which are different) for clang 5.0.0.

  Reported by:	Mark Millard

MFC r321439 (by bdrewery):

  Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.

  The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
  sysroot) and are only ever included from a compilation.  So using
  a beforebuild target here removes the file before the compilation
  tries to include it.

MFC r321664:

  Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):

    [CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.

    This avoids excessive compile time. The case I'm looking at is
    Function.cpp from an old version of LLVM that still had the giant
    memcmp string matcher in it. Before r308322 this compiled in about 2
    minutes, after it, clang takes infinite* time to compile it. With
    this patch we're at 5 min, which is still bad but this is a
    pathological case.

    The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
    for user scanning. It's probably too high, but does the job and is
    very unlikely to regress anything.

    Fixes PR33900.

    * I'm impatient and aborted after 15 minutes, on the bug report it was
      killed after 2h.

  Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):

    [X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)

    D35067/rL308322 attempted to support up to 4 load pairs for memcmp
    inlining which resulted in regressions for some optimized libc memcmp
    implementations (PR33914).

    Until we can match these more optimal cases, this patch reduces the
    memcmp expansion to a maximum of 2 load pairs (which matches what we
    do for -Os).

    This patch should be considered for the 5.0.0 release branch as well

    Differential Revision: https://reviews.llvm.org/D35830

  These fix a hang (or extremely long compile time) when building older
  LLVM ports.

  Reported by:    antoine
  PR:             219139

MFC r321719:

  Pull in r309503 from upstream clang trunk (by Richard Smith):

    PR33902: Invalidate line number cache when adding more text to
    existing buffer.

    This led to crashes as the line number cache would report a bogus
    line number for a line of code, and we'd try to find a nonexistent
    column within the line when printing diagnostics.

  This fixes an assertion when building the graphics/champlain port.

  Reported by:	antoine, kwm
  PR:		219139

MFC r321723:

  Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
  upstream release_50 branch.  This is just after upstream's 5.0.0-rc1.

MFC r322320:

  Upgrade our copies of clang, llvm and libc++ to r310316 from the
  upstream release_50 branch.

MFC r322326 (by emaste):

  lldb: Make i386-*-freebsd expression work on JIT path

  * Enable i386 ABI creation for freebsd
  * Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
    syscall
  * Unlike linux, the last argument of mmap is actually 64-bit(off_t).
    This requires us to push an additional word for the higher order bits.
  * Prior to this change, ktrace dump will show mmap failures due to
    invalid argument coming from the 6th mmap argument.

  Submitted by:	Karnajit Wangkhem
  Differential Revision:	https://reviews.llvm.org/D34776

MFC r322360 (by emaste):

  lldb: Report inferior signals as signals, not exceptions, on FreeBSD

  This is the FreeBSD equivalent of LLVM r238549.

  This serves 2 purposes:

  * LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
    SIGFPE the way it is suppose to be handled. Prior to this fix these
    signals will neither create a coredump, nor exit from the debugger
    or work for signal handling scenario.
  * eInvalidCrashReason need not report "unknown crash reason" if we have
    a valid si_signo

  llvm.org/pr23699

  Patch by Karnajit Wangkhem

  Differential Revision:  https://reviews.llvm.org/D35223

  Submitted by:	Karnajit Wangkhem
  Obtained from:	LLVM r310591

MFC r322474 (by emaste):

  lld: Add `-z muldefs` option.

  Obtained from:	LLVM r310757

MFC r322740:

  Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
  upstream release_50 branch.

MFC r322855:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
  the upstream release_50 branch.

  As of this version, lib/msun's trig test should also work correctly
  again (see bug 220989 for more information).

  PR:		220989

MFC r323112:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
  the upstream release_50 branch.  This corresponds to 5.0.0 rc4.

  As of this version, the cad/stepcode port should now compile in a more
  reasonable time on i386 (see bug 221836 for more information).

  PR:		221836

MFC r323245:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 release (upstream r312559).

  Release notes for llvm, clang and lld will be available here soon:
  <http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>

  Relnotes:	yes

(cherry picked from commit 12cd91cf4c6b96a24427c0de5374916f2808d263)

8 files changed, 671 insertions, 73 deletions

diff --git a/contrib/llvm/lib/Support/Unix/DynamicLibrary.inc b/contrib/llvm/lib/Support/Unix/DynamicLibrary.inc
new file mode 100644
index 0000000..f05103c
--- /dev/null
+++ b/contrib/llvm/lib/Support/Unix/DynamicLibrary.inc
@@ -0,0 +1,135 @@
+//===- Unix/DynamicLibrary.cpp - Unix DL Implementation ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the UNIX specific implementation of DynamicLibrary.
+//
+//===----------------------------------------------------------------------===//
+
+#if defined(HAVE_DLFCN_H) && defined(HAVE_DLOPEN)
+#include <dlfcn.h>
+
+DynamicLibrary::HandleSet::~HandleSet() {
+  // Close the libraries in reverse order.
+  for (void *Handle : llvm::reverse(Handles))
+    ::dlclose(Handle);
+  if (Process)
+    ::dlclose(Process);
+
+  // llvm_shutdown called, Return to default
+  DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
+}
+
+void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
+  void *Handle = ::dlopen(File, RTLD_LAZY|RTLD_GLOBAL);
+  if (!Handle) {
+    if (Err) *Err = ::dlerror();
+    return &DynamicLibrary::Invalid;
+  }
+
+#ifdef __CYGWIN__
+  // Cygwin searches symbols only in the main
+  // with the handle of dlopen(NULL, RTLD_GLOBAL).
+  if (!File)
+    Handle = RTLD_DEFAULT;
+#endif
+
+  return Handle;
+}
+
+void DynamicLibrary::HandleSet::DLClose(void *Handle) {
+  ::dlclose(Handle);
+}
+
+void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
+  return ::dlsym(Handle, Symbol);
+}
+
+#else // !HAVE_DLOPEN
+
+DynamicLibrary::HandleSet::~HandleSet() {}
+
+void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
+  if (Err) *Err = "dlopen() not supported on this platform";
+  return &Invalid;
+}
+
+void DynamicLibrary::HandleSet::DLClose(void *Handle) {
+}
+
+void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
+  return nullptr;
+}
+
+#endif
+
+// Must declare the symbols in the global namespace.
+static void *DoSearch(const char* SymbolName) {
+#define EXPLICIT_SYMBOL(SYM) \
+   extern void *SYM; if (!strcmp(SymbolName, #SYM)) return &SYM
+
+  // If this is darwin, it has some funky issues, try to solve them here.  Some
+  // important symbols are marked 'private external' which doesn't allow
+  // SearchForAddressOfSymbol to find them.  As such, we special case them here,
+  // there is only a small handful of them.
+
+#ifdef __APPLE__
+  {
+    // __eprintf is sometimes used for assert() handling on x86.
+    //
+    // FIXME: Currently disabled when using Clang, as we don't always have our
+    // runtime support libraries available.
+#ifndef __clang__
+#ifdef __i386__
+    EXPLICIT_SYMBOL(__eprintf);
+#endif
+#endif
+  }
+#endif
+
+#ifdef __CYGWIN__
+  {
+    EXPLICIT_SYMBOL(_alloca);
+    EXPLICIT_SYMBOL(__main);
+  }
+#endif
+
+#undef EXPLICIT_SYMBOL
+
+// This macro returns the address of a well-known, explicit symbol
+#define EXPLICIT_SYMBOL(SYM) \
+   if (!strcmp(SymbolName, #SYM)) return &SYM
+
+// Under glibc we have a weird situation. The stderr/out/in symbols are both
+// macros and global variables because of standards requirements. So, we
+// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
+#if defined(__GLIBC__)
+  {
+    EXPLICIT_SYMBOL(stderr);
+    EXPLICIT_SYMBOL(stdout);
+    EXPLICIT_SYMBOL(stdin);
+  }
+#else
+  // For everything else, we want to check to make sure the symbol isn't defined
+  // as a macro before using EXPLICIT_SYMBOL.
+  {
+#ifndef stdin
+    EXPLICIT_SYMBOL(stdin);
+#endif
+#ifndef stdout
+    EXPLICIT_SYMBOL(stdout);
+#endif
+#ifndef stderr
+    EXPLICIT_SYMBOL(stderr);
+#endif
+  }
+#endif
+#undef EXPLICIT_SYMBOL
+
+  return nullptr;
+}
diff --git a/contrib/llvm/lib/Support/Unix/Host.inc b/contrib/llvm/lib/Support/Unix/Host.inc
index 4572171..5580e63 100644
--- a/contrib/llvm/lib/Support/Unix/Host.inc
+++ b/contrib/llvm/lib/Support/Unix/Host.inc
@@ -34,16 +34,35 @@ static std::string getOSVersion() {
   return info.release;
 }
 
-std::string sys::getDefaultTargetTriple() {
-  std::string TargetTripleString(LLVM_DEFAULT_TARGET_TRIPLE);
-
-  // On darwin, we want to update the version to match that of the
-  // target.
+static std::string updateTripleOSVersion(std::string TargetTripleString) {
+  // On darwin, we want to update the version to match that of the target.
   std::string::size_type DarwinDashIdx = TargetTripleString.find("-darwin");
   if (DarwinDashIdx != std::string::npos) {
     TargetTripleString.resize(DarwinDashIdx + strlen("-darwin"));
     TargetTripleString += getOSVersion();
+    return TargetTripleString;
+  }
+  std::string::size_type MacOSDashIdx = TargetTripleString.find("-macos");
+  if (MacOSDashIdx != std::string::npos) {
+    TargetTripleString.resize(MacOSDashIdx);
+    // Reset the OS to darwin as the OS version from `uname` doesn't use the
+    // macOS version scheme.
+    TargetTripleString += "-darwin";
+    TargetTripleString += getOSVersion();
   }
+  return TargetTripleString;
+}
+
+std::string sys::getDefaultTargetTriple() {
+  std::string TargetTripleString =
+      updateTripleOSVersion(LLVM_DEFAULT_TARGET_TRIPLE);
+
+  // Override the default target with an environment variable named by
+  // LLVM_TARGET_TRIPLE_ENV.
+#if defined(LLVM_TARGET_TRIPLE_ENV)
+  if (const char *EnvTriple = std::getenv(LLVM_TARGET_TRIPLE_ENV))
+    TargetTripleString = EnvTriple;
+#endif
 
   return Triple::normalize(TargetTripleString);
 }
diff --git a/contrib/llvm/lib/Support/Unix/Memory.inc b/contrib/llvm/lib/Support/Unix/Memory.inc
index edbc793..dd39ef9 100644
--- a/contrib/llvm/lib/Support/Unix/Memory.inc
+++ b/contrib/llvm/lib/Support/Unix/Memory.inc
@@ -195,6 +195,10 @@ Memory::AllocateRWX(size_t NumBytes, const MemoryBlock* NearBlock,
 #if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
   void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
                     flags, fd, 0);
+#elif defined(__NetBSD__) && defined(PROT_MPROTECT)
+  void *pa =
+      ::mmap(start, PageSize * NumPages,
+             PROT_READ | PROT_WRITE | PROT_MPROTECT(PROT_EXEC), flags, fd, 0);
 #else
   void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
                     flags, fd, 0);
diff --git a/contrib/llvm/lib/Support/Unix/Path.inc b/contrib/llvm/lib/Support/Unix/Path.inc
index e0b11aa..45097eb 100644
--- a/contrib/llvm/lib/Support/Unix/Path.inc
+++ b/contrib/llvm/lib/Support/Unix/Path.inc
@@ -48,6 +48,8 @@
 # endif
 #endif
 
+#include <pwd.h>
+
 #ifdef __APPLE__
 #include <mach-o/dyld.h>
 #include <sys/attr.h>
@@ -65,23 +67,41 @@
 #endif
 
 #include <sys/types.h>
-#if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(__ANDROID__)
+#if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(__FreeBSD__) &&   \
+    !defined(__linux__)
 #include <sys/statvfs.h>
 #define STATVFS statvfs
+#define FSTATVFS fstatvfs
 #define STATVFS_F_FRSIZE(vfs) vfs.f_frsize
 #else
-#ifdef __OpenBSD__
-#include <sys/param.h>
+#if defined(__OpenBSD__) || defined(__FreeBSD__)
 #include <sys/mount.h>
-#elif defined(__ANDROID__)
+#include <sys/param.h>
+#elif defined(__linux__)
+#if defined(HAVE_LINUX_MAGIC_H)
+#include <linux/magic.h>
+#else
+#if defined(HAVE_LINUX_NFS_FS_H)
+#include <linux/nfs_fs.h>
+#endif
+#if defined(HAVE_LINUX_SMB_H)
+#include <linux/smb.h>
+#endif
+#endif
 #include <sys/vfs.h>
 #else
 #include <sys/mount.h>
 #endif
 #define STATVFS statfs
+#define FSTATVFS fstatfs
 #define STATVFS_F_FRSIZE(vfs) static_cast<uint64_t>(vfs.f_bsize)
 #endif
 
+#if defined(__NetBSD__)
+#define STATVFS_F_FLAG(vfs) (vfs).f_flag
+#else
+#define STATVFS_F_FLAG(vfs) (vfs).f_flags
+#endif
 
 using namespace llvm;
 
@@ -180,7 +200,7 @@ std::string getMainExecutable(const char *argv0, void *MainAddr) {
       if (getprogpath(exe_path, argv0))
         return exe_path;
   }
-#elif defined(HAVE_DLFCN_H)
+#elif defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)
   // Use dladdr to get executable path if available.
   Dl_info DLInfo;
   int err = dladdr(MainAddr, &DLInfo);
@@ -210,6 +230,10 @@ UniqueID file_status::getUniqueID() const {
   return UniqueID(fs_st_dev, fs_st_ino);
 }
 
+uint32_t file_status::getLinkCount() const {
+  return fs_st_nlinks;
+}
+
 ErrorOr<space_info> disk_space(const Twine &Path) {
   struct STATVFS Vfs;
   if (::STATVFS(Path.str().c_str(), &Vfs))
@@ -257,6 +281,16 @@ std::error_code current_path(SmallVectorImpl<char> &result) {
   return std::error_code();
 }
 
+std::error_code set_current_path(const Twine &path) {
+  SmallString<128> path_storage;
+  StringRef p = path.toNullTerminatedStringRef(path_storage);
+
+  if (::chdir(p.begin()) == -1)
+    return std::error_code(errno, std::generic_category());
+
+  return std::error_code();
+}
+
 std::error_code create_directory(const Twine &path, bool IgnoreExisting,
                                  perms Perms) {
   SmallString<128> path_storage;
@@ -325,6 +359,56 @@ std::error_code remove(const Twine &path, bool IgnoreNonExisting) {
   return std::error_code();
 }
 
+static bool is_local_impl(struct STATVFS &Vfs) {
+#if defined(__linux__)
+#ifndef NFS_SUPER_MAGIC
+#define NFS_SUPER_MAGIC 0x6969
+#endif
+#ifndef SMB_SUPER_MAGIC
+#define SMB_SUPER_MAGIC 0x517B
+#endif
+#ifndef CIFS_MAGIC_NUMBER
+#define CIFS_MAGIC_NUMBER 0xFF534D42
+#endif
+  switch ((uint32_t)Vfs.f_type) {
+  case NFS_SUPER_MAGIC:
+  case SMB_SUPER_MAGIC:
+  case CIFS_MAGIC_NUMBER:
+    return false;
+  default:
+    return true;
+  }
+#elif defined(__CYGWIN__)
+  // Cygwin doesn't expose this information; would need to use Win32 API.
+  return false;
+#elif defined(__sun)
+  // statvfs::f_basetype contains a null-terminated FSType name of the mounted target
+  StringRef fstype(Vfs.f_basetype);
+  // NFS is the only non-local fstype??
+  return !fstype.equals("nfs");
+#else
+  return !!(STATVFS_F_FLAG(Vfs) & MNT_LOCAL);
+#endif
+}
+
+std::error_code is_local(const Twine &Path, bool &Result) {
+  struct STATVFS Vfs;
+  if (::STATVFS(Path.str().c_str(), &Vfs))
+    return std::error_code(errno, std::generic_category());
+
+  Result = is_local_impl(Vfs);
+  return std::error_code();
+}
+
+std::error_code is_local(int FD, bool &Result) {
+  struct STATVFS Vfs;
+  if (::FSTATVFS(FD, &Vfs))
+    return std::error_code(errno, std::generic_category());
+
+  Result = is_local_impl(Vfs);
+  return std::error_code();
+}
+
 std::error_code rename(const Twine &from, const Twine &to) {
   // Get arguments.
   SmallString<128> from_storage;
@@ -342,14 +426,15 @@ std::error_code resize_file(int FD, uint64_t Size) {
 #if defined(HAVE_POSIX_FALLOCATE)
   // If we have posix_fallocate use it. Unlike ftruncate it always allocates
   // space, so we get an error if the disk is full.
-  if (int Err = ::posix_fallocate(FD, 0, Size))
-    return std::error_code(Err, std::generic_category());
-#else
+  if (int Err = ::posix_fallocate(FD, 0, Size)) {
+    if (Err != EOPNOTSUPP)
+      return std::error_code(Err, std::generic_category());
+  }
+#endif
   // Use ftruncate as a fallback. It may or may not allocate space. At least on
   // OS X with HFS+ it does.
   if (::ftruncate(FD, Size) == -1)
     return std::error_code(errno, std::generic_category());
-#endif
 
   return std::error_code();
 }
@@ -405,6 +490,46 @@ std::error_code equivalent(const Twine &A, const Twine &B, bool &result) {
   return std::error_code();
 }
 
+static void expandTildeExpr(SmallVectorImpl<char> &Path) {
+  StringRef PathStr(Path.begin(), Path.size());
+  if (PathStr.empty() || !PathStr.startswith("~"))
+    return;
+
+  PathStr = PathStr.drop_front();
+  StringRef Expr =
+      PathStr.take_until([](char c) { return path::is_separator(c); });
+  StringRef Remainder = PathStr.substr(Expr.size() + 1);
+  SmallString<128> Storage;
+  if (Expr.empty()) {
+    // This is just ~/..., resolve it to the current user's home dir.
+    if (!path::home_directory(Storage)) {
+      // For some reason we couldn't get the home directory.  Just exit.
+      return;
+    }
+
+    // Overwrite the first character and insert the rest.
+    Path[0] = Storage[0];
+    Path.insert(Path.begin() + 1, Storage.begin() + 1, Storage.end());
+    return;
+  }
+
+  // This is a string of the form ~username/, look up this user's entry in the
+  // password database.
+  struct passwd *Entry = nullptr;
+  std::string User = Expr.str();
+  Entry = ::getpwnam(User.c_str());
+
+  if (!Entry) {
+    // Unable to look up the entry, just return back the original path.
+    return;
+  }
+
+  Storage = Remainder;
+  Path.clear();
+  Path.append(Entry->pw_dir, Entry->pw_dir + strlen(Entry->pw_dir));
+  llvm::sys::path::append(Path, Storage);
+}
+
 static std::error_code fillStatus(int StatRet, const struct stat &Status,
                              file_status &Result) {
   if (StatRet != 0) {
@@ -430,22 +555,23 @@ static std::error_code fillStatus(int StatRet, const struct stat &Status,
     Type = file_type::fifo_file;
   else if (S_ISSOCK(Status.st_mode))
     Type = file_type::socket_file;
+  else if (S_ISLNK(Status.st_mode))
+    Type = file_type::symlink_file;
 
-  perms Perms = static_cast<perms>(Status.st_mode);
-  Result =
-      file_status(Type, Perms, Status.st_dev, Status.st_ino, Status.st_atime,
-                  Status.st_mtime, Status.st_uid, Status.st_gid,
-                  Status.st_size);
+  perms Perms = static_cast<perms>(Status.st_mode) & all_perms;
+  Result = file_status(Type, Perms, Status.st_dev, Status.st_nlink,
+                       Status.st_ino, Status.st_atime, Status.st_mtime,
+                       Status.st_uid, Status.st_gid, Status.st_size);
 
   return std::error_code();
 }
 
-std::error_code status(const Twine &Path, file_status &Result) {
+std::error_code status(const Twine &Path, file_status &Result, bool Follow) {
   SmallString<128> PathStorage;
   StringRef P = Path.toNullTerminatedStringRef(PathStorage);
 
   struct stat Status;
-  int StatRet = ::stat(P.begin(), &Status);
+  int StatRet = (Follow ? ::stat : ::lstat)(P.begin(), &Status);
   return fillStatus(StatRet, Status, Result);
 }
 
@@ -455,6 +581,15 @@ std::error_code status(int FD, file_status &Result) {
   return fillStatus(StatRet, Status, Result);
 }
 
+std::error_code setPermissions(const Twine &Path, perms Permissions) {
+  SmallString<128> PathStorage;
+  StringRef P = Path.toNullTerminatedStringRef(PathStorage);
+
+  if (::chmod(P.begin(), Permissions))
+    return std::error_code(errno, std::generic_category());
+  return std::error_code();
+}
+
 std::error_code setLastModificationAndAccessTime(int FD, TimePoint<> Time) {
 #if defined(HAVE_FUTIMENS)
   timespec Times[2];
@@ -481,6 +616,26 @@ std::error_code mapped_file_region::init(int FD, uint64_t Offset,
 
   int flags = (Mode == readwrite) ? MAP_SHARED : MAP_PRIVATE;
   int prot = (Mode == readonly) ? PROT_READ : (PROT_READ | PROT_WRITE);
+#if defined(__APPLE__)
+  //----------------------------------------------------------------------
+  // Newer versions of MacOSX have a flag that will allow us to read from
+  // binaries whose code signature is invalid without crashing by using
+  // the MAP_RESILIENT_CODESIGN flag. Also if a file from removable media
+  // is mapped we can avoid crashing and return zeroes to any pages we try
+  // to read if the media becomes unavailable by using the
+  // MAP_RESILIENT_MEDIA flag.  These flags are only usable when mapping
+  // with PROT_READ, so take care not to specify them otherwise.
+  //----------------------------------------------------------------------
+  if (Mode == readonly) {
+#if defined(MAP_RESILIENT_CODESIGN)
+    flags |= MAP_RESILIENT_CODESIGN;
+#endif
+#if defined(MAP_RESILIENT_MEDIA)
+    flags |= MAP_RESILIENT_MEDIA;
+#endif
+  }
+#endif // #if defined (__APPLE__)
+
   Mapping = ::mmap(nullptr, Size, prot, flags, FD, Offset);
   if (Mapping == MAP_FAILED)
     return std::error_code(errno, std::generic_category());
@@ -526,7 +681,8 @@ int mapped_file_region::alignment() {
 }
 
 std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
-                                                StringRef path){
+                                                     StringRef path,
+                                                     bool follow_symlinks) {
   SmallString<128> path_null(path);
   DIR *directory = ::opendir(path_null.c_str());
   if (!directory)
@@ -535,7 +691,7 @@ std::error_code detail::directory_iterator_construct(detail::DirIterState &it,
   it.IterationHandle = reinterpret_cast<intptr_t>(directory);
   // Add something for replace_filename to replace.
   path::append(path_null, ".");
-  it.CurrentEntry = directory_entry(path_null.str());
+  it.CurrentEntry = directory_entry(path_null.str(), follow_symlinks);
   return directory_iterator_increment(it);
 }
 
@@ -577,10 +733,17 @@ std::error_code openFileForRead(const Twine &Name, int &ResultFD,
                                 SmallVectorImpl<char> *RealPath) {
   SmallString<128> Storage;
   StringRef P = Name.toNullTerminatedStringRef(Storage);
-  while ((ResultFD = open(P.begin(), O_RDONLY)) < 0) {
-    if (errno != EINTR)
-      return std::error_code(errno, std::generic_category());
-  }
+  int OpenFlags = O_RDONLY;
+#ifdef O_CLOEXEC
+  OpenFlags |= O_CLOEXEC;
+#endif
+  if ((ResultFD = sys::RetryAfterSignal(-1, open, P.begin(), OpenFlags)) < 0)
+    return std::error_code(errno, std::generic_category());
+#ifndef O_CLOEXEC
+  int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);
+  (void)r;
+  assert(r == 0 && "fcntl(F_SETFD, FD_CLOEXEC) failed");
+#endif
   // Attempt to get the real name of the file, if the user asked
   if(!RealPath)
     return std::error_code();
@@ -616,6 +779,10 @@ std::error_code openFileForWrite(const Twine &Name, int &ResultFD,
 
   int OpenFlags = O_CREAT;
 
+#ifdef O_CLOEXEC
+  OpenFlags |= O_CLOEXEC;
+#endif
+
   if (Flags & F_RW)
     OpenFlags |= O_RDWR;
   else
@@ -631,10 +798,13 @@ std::error_code openFileForWrite(const Twine &Name, int &ResultFD,
 
   SmallString<128> Storage;
   StringRef P = Name.toNullTerminatedStringRef(Storage);
-  while ((ResultFD = open(P.begin(), OpenFlags, Mode)) < 0) {
-    if (errno != EINTR)
-      return std::error_code(errno, std::generic_category());
-  }
+  if ((ResultFD = sys::RetryAfterSignal(-1, open, P.begin(), OpenFlags, Mode)) < 0)
+    return std::error_code(errno, std::generic_category());
+#ifndef O_CLOEXEC
+  int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);
+  (void)r;
+  assert(r == 0 && "fcntl(F_SETFD, FD_CLOEXEC) failed");
+#endif
   return std::error_code();
 }
 
@@ -685,18 +855,85 @@ std::error_code getPathFromOpenFD(int FD, SmallVectorImpl<char> &ResultPath) {
   return std::error_code();
 }
 
+template <typename T>
+static std::error_code remove_directories_impl(const T &Entry,
+                                               bool IgnoreErrors) {
+  std::error_code EC;
+  directory_iterator Begin(Entry, EC, false);
+  directory_iterator End;
+  while (Begin != End) {
+    auto &Item = *Begin;
+    file_status st;
+    EC = Item.status(st);
+    if (EC && !IgnoreErrors)
+      return EC;
+
+    if (is_directory(st)) {
+      EC = remove_directories_impl(Item, IgnoreErrors);
+      if (EC && !IgnoreErrors)
+        return EC;
+    }
+
+    EC = fs::remove(Item.path(), true);
+    if (EC && !IgnoreErrors)
+      return EC;
+
+    Begin.increment(EC);
+    if (EC && !IgnoreErrors)
+      return EC;
+  }
+  return std::error_code();
+}
+
+std::error_code remove_directories(const Twine &path, bool IgnoreErrors) {
+  auto EC = remove_directories_impl(path, IgnoreErrors);
+  if (EC && !IgnoreErrors)
+    return EC;
+  EC = fs::remove(path, true);
+  if (EC && !IgnoreErrors)
+    return EC;
+  return std::error_code();
+}
+
+std::error_code real_path(const Twine &path, SmallVectorImpl<char> &dest,
+                          bool expand_tilde) {
+  dest.clear();
+  if (path.isTriviallyEmpty())
+    return std::error_code();
+
+  if (expand_tilde) {
+    SmallString<128> Storage;
+    path.toVector(Storage);
+    expandTildeExpr(Storage);
+    return real_path(Storage, dest, false);
+  }
+
+  int fd;
+  std::error_code EC = openFileForRead(path, fd, &dest);
+
+  if (EC)
+    return EC;
+  ::close(fd);
+  return std::error_code();
+}
+
 } // end namespace fs
 
 namespace path {
 
 bool home_directory(SmallVectorImpl<char> &result) {
-  if (char *RequestedDir = getenv("HOME")) {
-    result.clear();
-    result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
-    return true;
+  char *RequestedDir = getenv("HOME");
+  if (!RequestedDir) {
+    struct passwd *pw = getpwuid(getuid());
+    if (pw && pw->pw_dir)
+      RequestedDir = pw->pw_dir;
   }
+  if (!RequestedDir)
+    return false;
 
-  return false;
+  result.clear();
+  result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
+  return true;
 }
 
 static bool getDarwinConfDir(bool TempDir, SmallVectorImpl<char> &Result) {
diff --git a/contrib/llvm/lib/Support/Unix/Process.inc b/contrib/llvm/lib/Support/Unix/Process.inc
index 16f8f5a..2d46620 100644
--- a/contrib/llvm/lib/Support/Unix/Process.inc
+++ b/contrib/llvm/lib/Support/Unix/Process.inc
@@ -207,13 +207,10 @@ std::error_code Process::FixupStandardFileDescriptors() {
   for (int StandardFD : StandardFDs) {
     struct stat st;
     errno = 0;
-    while (fstat(StandardFD, &st) < 0) {
+    if (RetryAfterSignal(-1, fstat, StandardFD, &st) < 0) {
       assert(errno && "expected errno to be set if fstat failed!");
       // fstat should return EBADF if the file descriptor is closed.
-      if (errno == EBADF)
-        break;
-      // retry fstat if we got EINTR, otherwise bubble up the failure.
-      if (errno != EINTR)
+      if (errno != EBADF)
         return std::error_code(errno, std::generic_category());
     }
     // if fstat succeeds, move on to the next FD.
@@ -222,11 +219,8 @@ std::error_code Process::FixupStandardFileDescriptors() {
     assert(errno == EBADF && "expected errno to have EBADF at this point!");
 
     if (NullFD < 0) {
-      while ((NullFD = open("/dev/null", O_RDWR)) < 0) {
-        if (errno == EINTR)
-          continue;
+      if ((NullFD = RetryAfterSignal(-1, open, "/dev/null", O_RDWR)) < 0)
         return std::error_code(errno, std::generic_category());
-      }
     }
 
     if (NullFD == StandardFD)
@@ -347,7 +341,7 @@ static bool terminalHasColors(int fd) {
   MutexGuard G(*TermColorMutex);
 
   int errret = 0;
-  if (setupterm((char *)nullptr, fd, &errret) != 0)
+  if (setupterm(nullptr, fd, &errret) != 0)
     // Regardless of why, if we can't get terminfo, we shouldn't try to print
     // colors.
     return false;
@@ -369,7 +363,7 @@ static bool terminalHasColors(int fd) {
 
   // Now extract the structure allocated by setupterm and free its memory
   // through a really silly dance.
-  struct term *termp = set_curterm((struct term *)nullptr);
+  struct term *termp = set_curterm(nullptr);
   (void)del_curterm(termp); // Drop any errors here.
 
   // Return true if we found a color capabilities for the current terminal.
diff --git a/contrib/llvm/lib/Support/Unix/Program.inc b/contrib/llvm/lib/Support/Unix/Program.inc
index 7d3537e..c866d5b 100644
--- a/contrib/llvm/lib/Support/Unix/Program.inc
+++ b/contrib/llvm/lib/Support/Unix/Program.inc
@@ -40,9 +40,6 @@
 #include <unistd.h>
 #endif
 #ifdef HAVE_POSIX_SPAWN
-#ifdef __sun__
-#define  _RESTRICT_KYWD
-#endif
 #include <spawn.h>
 
 #if defined(__APPLE__)
@@ -163,16 +160,6 @@ static void SetMemoryLimits (unsigned size)
   r.rlim_cur = limit;
   setrlimit (RLIMIT_RSS, &r);
 #endif
-#ifdef RLIMIT_AS  // e.g. NetBSD doesn't have it.
-  // Don't set virtual memory limit if built with any Sanitizer. They need 80Tb
-  // of virtual memory for shadow memory mapping.
-#if !LLVM_MEMORY_SANITIZER_BUILD && !LLVM_ADDRESS_SANITIZER_BUILD
-  // Virtual memory.
-  getrlimit (RLIMIT_AS, &r);
-  r.rlim_cur = limit;
-  setrlimit (RLIMIT_AS, &r);
-#endif
-#endif
 #endif
 }
 
@@ -459,11 +446,22 @@ bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef<co
   size_t ArgLength = Program.size() + 1;
   for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
-    ArgLength += strlen(*I) + 1;
+    size_t length = strlen(*I);
+
+    // Ensure that we do not exceed the MAX_ARG_STRLEN constant on Linux, which
+    // does not have a constant unlike what the man pages would have you
+    // believe. Since this limit is pretty high, perform the check
+    // unconditionally rather than trying to be aggressive and limiting it to
+    // Linux only.
+    if (length >= (32 * 4096))
+      return false;
+
+    ArgLength += length + 1;
     if (ArgLength > size_t(HalfArgMax)) {
       return false;
     }
   }
+
   return true;
 }
 }
diff --git a/contrib/llvm/lib/Support/Unix/Signals.inc b/contrib/llvm/lib/Support/Unix/Signals.inc
index 9752b70..aaf760c 100644
--- a/contrib/llvm/lib/Support/Unix/Signals.inc
+++ b/contrib/llvm/lib/Support/Unix/Signals.inc
@@ -15,9 +15,9 @@
 #include "Unix.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Demangle/Demangle.h"
-#include "llvm/Support/Format.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FileUtilities.h"
+#include "llvm/Support/Format.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
 #include "llvm/Support/Program.h"
@@ -25,8 +25,8 @@
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <string>
-#if HAVE_EXECINFO_H
-# include <execinfo.h>         // For backtrace().
+#ifdef HAVE_BACKTRACE
+# include BACKTRACE_HEADER         // For backtrace().
 #endif
 #if HAVE_SIGNAL_H
 #include <signal.h>
@@ -59,7 +59,7 @@ using namespace llvm;
 
 static RETSIGTYPE SignalHandler(int Sig);  // defined below.
 
-static ManagedStatic<SmartMutex<true> > SignalsMutex;
+static ManagedStatic<sys::SmartMutex<true> > SignalsMutex;
 
 /// InterruptFunction - The function to call if ctrl-c is pressed.
 static void (*InterruptFunction)() = nullptr;
@@ -149,11 +149,7 @@ static void CreateSigAltStack() {}
 #endif
 
 static void RegisterHandlers() {
-  // We need to dereference the signals mutex during handler registration so
-  // that we force its construction. This is to prevent the first use being
-  // during handling an actual signal because you can't safely call new in a
-  // signal handler.
-  *SignalsMutex;
+  sys::SmartScopedLock<true> Guard(*SignalsMutex);
 
   // If the handlers are already registered, we're done.
   if (NumRegisteredSignals != 0) return;
@@ -223,7 +219,7 @@ static RETSIGTYPE SignalHandler(int Sig) {
   sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
 
   {
-    unique_lock<SmartMutex<true>> Guard(*SignalsMutex);
+    unique_lock<sys::SmartMutex<true>> Guard(*SignalsMutex);
     RemoveFilesToRemove();
 
     if (std::find(std::begin(IntSigs), std::end(IntSigs), Sig)
@@ -412,7 +408,7 @@ void llvm::sys::PrintStackTrace(raw_ostream &OS) {
 
   if (printSymbolizedStackTrace(Argv0, StackTrace, depth, OS))
     return;
-#if HAVE_DLFCN_H && __GNUG__ && !defined(__CYGWIN__)
+#if HAVE_DLFCN_H && HAVE_DLADDR
   int width = 0;
   for (int i = 0; i < depth; ++i) {
     Dl_info dlinfo;
@@ -462,7 +458,7 @@ void llvm::sys::PrintStackTrace(raw_ostream &OS) {
 }
 
 static void PrintStackTraceSignalHandler(void *) {
-  PrintStackTrace(llvm::errs());
+  sys::PrintStackTrace(llvm::errs());
 }
 
 void llvm::sys::DisableSystemDialogsOnCrash() {}
diff --git a/contrib/llvm/lib/Support/Unix/Threading.inc b/contrib/llvm/lib/Support/Unix/Threading.inc
new file mode 100644
index 0000000..267af38
--- /dev/null
+++ b/contrib/llvm/lib/Support/Unix/Threading.inc
@@ -0,0 +1,215 @@
+//===- Unix/Threading.inc - Unix Threading Implementation ----- -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the Unix specific implementation of Threading functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/Twine.h"
+
+#if defined(__APPLE__)
+#include <mach/mach_init.h>
+#include <mach/mach_port.h>
+#endif
+
+#include <pthread.h>
+
+#if defined(__FreeBSD__)
+#include <pthread_np.h> // For pthread_getthreadid_np()
+#endif
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#include <errno.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#include <unistd.h>
+#endif
+
+#if defined(__NetBSD__)
+#include <lwp.h> // For _lwp_self()
+#endif
+
+#if defined(__linux__)
+#include <sys/syscall.h> // For syscall codes
+#include <unistd.h>      // For syscall()
+#endif
+
+namespace {
+  struct ThreadInfo {
+    void(*UserFn)(void *);
+    void *UserData;
+  };
+}
+
+static void *ExecuteOnThread_Dispatch(void *Arg) {
+  ThreadInfo *TI = reinterpret_cast<ThreadInfo*>(Arg);
+  TI->UserFn(TI->UserData);
+  return nullptr;
+}
+
+void llvm::llvm_execute_on_thread(void(*Fn)(void*), void *UserData,
+  unsigned RequestedStackSize) {
+  ThreadInfo Info = { Fn, UserData };
+  pthread_attr_t Attr;
+  pthread_t Thread;
+
+  // Construct the attributes object.
+  if (::pthread_attr_init(&Attr) != 0)
+    return;
+
+  // Set the requested stack size, if given.
+  if (RequestedStackSize != 0) {
+    if (::pthread_attr_setstacksize(&Attr, RequestedStackSize) != 0)
+      goto error;
+  }
+
+  // Construct and execute the thread.
+  if (::pthread_create(&Thread, &Attr, ExecuteOnThread_Dispatch, &Info) != 0)
+    goto error;
+
+  // Wait for the thread and clean up.
+  ::pthread_join(Thread, nullptr);
+
+error:
+  ::pthread_attr_destroy(&Attr);
+}
+
+
+uint64_t llvm::get_threadid() {
+#if defined(__APPLE__)
+  // Calling "mach_thread_self()" bumps the reference count on the thread
+  // port, so we need to deallocate it. mach_task_self() doesn't bump the ref
+  // count.
+  thread_port_t Self = mach_thread_self();
+  mach_port_deallocate(mach_task_self(), Self);
+  return Self;
+#elif defined(__FreeBSD__)
+  return uint64_t(pthread_getthreadid_np());
+#elif defined(__NetBSD__)
+  return uint64_t(_lwp_self());
+#elif defined(__ANDROID__)
+  return uint64_t(gettid());
+#elif defined(__linux__)
+  return uint64_t(syscall(SYS_gettid));
+#elif defined(LLVM_ON_WIN32)
+  return uint64_t(::GetCurrentThreadId());
+#else
+  return uint64_t(pthread_self());
+#endif
+}
+
+
+static constexpr uint32_t get_max_thread_name_length_impl() {
+#if defined(__NetBSD__)
+	return PTHREAD_MAX_NAMELEN_NP;
+#elif defined(__APPLE__)
+	return 64;
+#elif defined(__linux__)
+#if HAVE_PTHREAD_SETNAME_NP
+	return 16;
+#else
+	return 0;
+#endif
+#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+  return 16;
+#else
+  return 0;
+#endif
+}
+
+uint32_t llvm::get_max_thread_name_length() {
+  return get_max_thread_name_length_impl();
+}
+
+void llvm::set_thread_name(const Twine &Name) {
+  // Make sure the input is null terminated.
+  SmallString<64> Storage;
+  StringRef NameStr = Name.toNullTerminatedStringRef(Storage);
+
+  // Truncate from the beginning, not the end, if the specified name is too
+  // long.  For one, this ensures that the resulting string is still null
+  // terminated, but additionally the end of a long thread name will usually
+  // be more unique than the beginning, since a common pattern is for similar
+  // threads to share a common prefix.
+  if (get_max_thread_name_length() > 0)
+    NameStr = NameStr.take_back(get_max_thread_name_length());
+  (void)NameStr;
+#if defined(__linux__)
+#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
+#if HAVE_PTHREAD_SETNAME_NP
+  ::pthread_setname_np(::pthread_self(), NameStr.data());
+#endif
+#endif
+#elif defined(__FreeBSD__)
+  ::pthread_set_name_np(::pthread_self(), NameStr.data());
+#elif defined(__NetBSD__)
+  ::pthread_setname_np(::pthread_self(), "%s",
+    const_cast<char *>(NameStr.data()));
+#elif defined(__APPLE__)
+  ::pthread_setname_np(NameStr.data());
+#endif
+}
+
+void llvm::get_thread_name(SmallVectorImpl<char> &Name) {
+  Name.clear();
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+  int pid = ::getpid();
+  uint64_t tid = get_threadid();
+
+  struct kinfo_proc *kp = nullptr, *nkp;
+  size_t len = 0;
+  int error;
+  int ctl[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD,
+    (int)pid };
+
+  while (1) {
+    error = sysctl(ctl, 4, kp, &len, nullptr, 0);
+    if (kp == nullptr || (error != 0 && errno == ENOMEM)) {
+      // Add extra space in case threads are added before next call.
+      len += sizeof(*kp) + len / 10;
+      nkp = (struct kinfo_proc *)realloc(kp, len);
+      if (nkp == nullptr) {
+        free(kp);
+        return;
+      }
+      kp = nkp;
+      continue;
+    }
+    if (error != 0)
+      len = 0;
+    break;
+  }
+
+  for (size_t i = 0; i < len / sizeof(*kp); i++) {
+    if (kp[i].ki_tid == (lwpid_t)tid) {
+      Name.append(kp[i].ki_tdname, kp[i].ki_tdname + strlen(kp[i].ki_tdname));
+      break;
+    }
+  }
+  free(kp);
+  return;
+#elif defined(__NetBSD__)
+  constexpr uint32_t len = get_max_thread_name_length_impl();
+  char buf[len];
+  ::pthread_getname_np(::pthread_self(), buf, len);
+
+  Name.append(buf, buf + strlen(buf));
+#elif defined(__linux__)
+#if (defined(__GLIBC__) && defined(_GNU_SOURCE)) || defined(__ANDROID__)
+#if HAVE_PTHREAD_GETNAME_NP
+  constexpr uint32_t len = get_max_thread_name_length_impl();
+  char Buffer[len];
+  if (0 == ::pthread_getname_np(::pthread_self(), Buffer, len))
+    Name.append(Buffer, Buffer + strlen(Buffer));
+#endif
+#endif
+#endif
+}