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)

1 files changed, 261 insertions, 389 deletions

diff --git a/contrib/llvm/lib/Support/Path.cpp b/contrib/llvm/lib/Support/Path.cpp
index 4bb035e..ea59ba6 100644
--- a/contrib/llvm/lib/Support/Path.cpp
+++ b/contrib/llvm/lib/Support/Path.cpp
@@ -11,13 +11,12 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Support/COFF.h"
-#include "llvm/Support/MachO.h"
+#include "llvm/Support/Path.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
-#include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include <cctype>
 #include <cstring>
@@ -34,16 +33,29 @@ using namespace llvm::support::endian;
 namespace {
   using llvm::StringRef;
   using llvm::sys::path::is_separator;
+  using llvm::sys::path::Style;
 
+  inline Style real_style(Style style) {
 #ifdef LLVM_ON_WIN32
-  const char *separators = "\\/";
-  const char preferred_separator = '\\';
+    return (style == Style::posix) ? Style::posix : Style::windows;
 #else
-  const char  separators = '/';
-  const char preferred_separator = '/';
+    return (style == Style::windows) ? Style::windows : Style::posix;
 #endif
+  }
+
+  inline const char *separators(Style style) {
+    if (real_style(style) == Style::windows)
+      return "\\/";
+    return "/";
+  }
+
+  inline char preferred_separator(Style style) {
+    if (real_style(style) == Style::windows)
+      return '\\';
+    return '/';
+  }
 
-  StringRef find_first_component(StringRef path) {
+  StringRef find_first_component(StringRef path, Style style) {
     // Look for this first component in the following order.
     // * empty (in this case we return an empty string)
     // * either C: or {//,\\}net.
@@ -53,96 +65,85 @@ namespace {
     if (path.empty())
       return path;
 
-#ifdef LLVM_ON_WIN32
-    // C:
-    if (path.size() >= 2 && std::isalpha(static_cast<unsigned char>(path[0])) &&
-        path[1] == ':')
-      return path.substr(0, 2);
-#endif
+    if (real_style(style) == Style::windows) {
+      // C:
+      if (path.size() >= 2 &&
+          std::isalpha(static_cast<unsigned char>(path[0])) && path[1] == ':')
+        return path.substr(0, 2);
+    }
 
     // //net
-    if ((path.size() > 2) &&
-        is_separator(path[0]) &&
-        path[0] == path[1] &&
-        !is_separator(path[2])) {
+    if ((path.size() > 2) && is_separator(path[0], style) &&
+        path[0] == path[1] && !is_separator(path[2], style)) {
       // Find the next directory separator.
-      size_t end = path.find_first_of(separators, 2);
+      size_t end = path.find_first_of(separators(style), 2);
       return path.substr(0, end);
     }
 
     // {/,\}
-    if (is_separator(path[0]))
+    if (is_separator(path[0], style))
       return path.substr(0, 1);
 
     // * {file,directory}name
-    size_t end = path.find_first_of(separators);
+    size_t end = path.find_first_of(separators(style));
     return path.substr(0, end);
   }
 
-  size_t filename_pos(StringRef str) {
-    if (str.size() == 2 &&
-        is_separator(str[0]) &&
-        str[0] == str[1])
+  size_t filename_pos(StringRef str, Style style) {
+    if (str.size() == 2 && is_separator(str[0], style) && str[0] == str[1])
       return 0;
 
-    if (str.size() > 0 && is_separator(str[str.size() - 1]))
+    if (str.size() > 0 && is_separator(str[str.size() - 1], style))
       return str.size() - 1;
 
-    size_t pos = str.find_last_of(separators, str.size() - 1);
+    size_t pos = str.find_last_of(separators(style), str.size() - 1);
 
-#ifdef LLVM_ON_WIN32
-    if (pos == StringRef::npos)
-      pos = str.find_last_of(':', str.size() - 2);
-#endif
+    if (real_style(style) == Style::windows) {
+      if (pos == StringRef::npos)
+        pos = str.find_last_of(':', str.size() - 2);
+    }
 
-    if (pos == StringRef::npos ||
-        (pos == 1 && is_separator(str[0])))
+    if (pos == StringRef::npos || (pos == 1 && is_separator(str[0], style)))
       return 0;
 
     return pos + 1;
   }
 
-  size_t root_dir_start(StringRef str) {
+  size_t root_dir_start(StringRef str, Style style) {
     // case "c:/"
-#ifdef LLVM_ON_WIN32
-    if (str.size() > 2 &&
-        str[1] == ':' &&
-        is_separator(str[2]))
-      return 2;
-#endif
+    if (real_style(style) == Style::windows) {
+      if (str.size() > 2 && str[1] == ':' && is_separator(str[2], style))
+        return 2;
+    }
 
     // case "//"
-    if (str.size() == 2 &&
-        is_separator(str[0]) &&
-        str[0] == str[1])
+    if (str.size() == 2 && is_separator(str[0], style) && str[0] == str[1])
       return StringRef::npos;
 
     // case "//net"
-    if (str.size() > 3 &&
-        is_separator(str[0]) &&
-        str[0] == str[1] &&
-        !is_separator(str[2])) {
-      return str.find_first_of(separators, 2);
+    if (str.size() > 3 && is_separator(str[0], style) && str[0] == str[1] &&
+        !is_separator(str[2], style)) {
+      return str.find_first_of(separators(style), 2);
     }
 
     // case "/"
-    if (str.size() > 0 && is_separator(str[0]))
+    if (str.size() > 0 && is_separator(str[0], style))
       return 0;
 
     return StringRef::npos;
   }
 
-  size_t parent_path_end(StringRef path) {
-    size_t end_pos = filename_pos(path);
+  size_t parent_path_end(StringRef path, Style style) {
+    size_t end_pos = filename_pos(path, style);
 
-    bool filename_was_sep = path.size() > 0 && is_separator(path[end_pos]);
+    bool filename_was_sep =
+        path.size() > 0 && is_separator(path[end_pos], style);
 
     // Skip separators except for root dir.
-    size_t root_dir_pos = root_dir_start(path.substr(0, end_pos));
+    size_t root_dir_pos = root_dir_start(path.substr(0, end_pos), style);
 
-    while(end_pos > 0 &&
-          (end_pos - 1) != root_dir_pos &&
-          is_separator(path[end_pos - 1]))
+    while (end_pos > 0 && (end_pos - 1) != root_dir_pos &&
+           is_separator(path[end_pos - 1], style))
       --end_pos;
 
     if (end_pos == 1 && root_dir_pos == 0 && filename_was_sep)
@@ -230,11 +231,12 @@ namespace llvm {
 namespace sys  {
 namespace path {
 
-const_iterator begin(StringRef path) {
+const_iterator begin(StringRef path, Style style) {
   const_iterator i;
   i.Path      = path;
-  i.Component = find_first_component(path);
+  i.Component = find_first_component(path, style);
   i.Position  = 0;
+  i.S = style;
   return i;
 }
 
@@ -259,27 +261,21 @@ const_iterator &const_iterator::operator++() {
 
   // Both POSIX and Windows treat paths that begin with exactly two separators
   // specially.
-  bool was_net = Component.size() > 2 &&
-    is_separator(Component[0]) &&
-    Component[1] == Component[0] &&
-    !is_separator(Component[2]);
+  bool was_net = Component.size() > 2 && is_separator(Component[0], S) &&
+                 Component[1] == Component[0] && !is_separator(Component[2], S);
 
   // Handle separators.
-  if (is_separator(Path[Position])) {
+  if (is_separator(Path[Position], S)) {
     // Root dir.
-    if (was_net
-#ifdef LLVM_ON_WIN32
+    if (was_net ||
         // c:/
-        || Component.endswith(":")
-#endif
-        ) {
+        (real_style(S) == Style::windows && Component.endswith(":"))) {
       Component = Path.substr(Position, 1);
       return *this;
     }
 
     // Skip extra separators.
-    while (Position != Path.size() &&
-           is_separator(Path[Position])) {
+    while (Position != Path.size() && is_separator(Path[Position], S)) {
       ++Position;
     }
 
@@ -292,7 +288,7 @@ const_iterator &const_iterator::operator++() {
   }
 
   // Find next component.
-  size_t end_pos = Path.find_first_of(separators, Position);
+  size_t end_pos = Path.find_first_of(separators(S), Position);
   Component = Path.slice(Position, end_pos);
 
   return *this;
@@ -306,10 +302,11 @@ ptrdiff_t const_iterator::operator-(const const_iterator &RHS) const {
   return Position - RHS.Position;
 }
 
-reverse_iterator rbegin(StringRef Path) {
+reverse_iterator rbegin(StringRef Path, Style style) {
   reverse_iterator I;
   I.Path = Path;
   I.Position = Path.size();
+  I.S = style;
   return ++I;
 }
 
@@ -324,10 +321,9 @@ reverse_iterator rend(StringRef Path) {
 reverse_iterator &reverse_iterator::operator++() {
   // If we're at the end and the previous char was a '/', return '.' unless
   // we are the root path.
-  size_t root_dir_pos = root_dir_start(Path);
-  if (Position == Path.size() &&
-      Path.size() > root_dir_pos + 1 &&
-      is_separator(Path[Position - 1])) {
+  size_t root_dir_pos = root_dir_start(Path, S);
+  if (Position == Path.size() && Path.size() > root_dir_pos + 1 &&
+      is_separator(Path[Position - 1], S)) {
     --Position;
     Component = ".";
     return *this;
@@ -336,13 +332,12 @@ reverse_iterator &reverse_iterator::operator++() {
   // Skip separators unless it's the root directory.
   size_t end_pos = Position;
 
-  while(end_pos > 0 &&
-        (end_pos - 1) != root_dir_pos &&
-        is_separator(Path[end_pos - 1]))
+  while (end_pos > 0 && (end_pos - 1) != root_dir_pos &&
+         is_separator(Path[end_pos - 1], S))
     --end_pos;
 
   // Find next separator.
-  size_t start_pos = filename_pos(Path.substr(0, end_pos));
+  size_t start_pos = filename_pos(Path.substr(0, end_pos), S);
   Component = Path.slice(start_pos, end_pos);
   Position = start_pos;
   return *this;
@@ -357,21 +352,15 @@ ptrdiff_t reverse_iterator::operator-(const reverse_iterator &RHS) const {
   return Position - RHS.Position;
 }
 
-StringRef root_path(StringRef path) {
-  const_iterator b = begin(path),
-                 pos = b,
-                 e = end(path);
+StringRef root_path(StringRef path, Style style) {
+  const_iterator b = begin(path, style), pos = b, e = end(path);
   if (b != e) {
-    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
-    bool has_drive =
-#ifdef LLVM_ON_WIN32
-      b->endswith(":");
-#else
-      false;
-#endif
+    bool has_net =
+        b->size() > 2 && is_separator((*b)[0], style) && (*b)[1] == (*b)[0];
+    bool has_drive = (real_style(style) == Style::windows) && b->endswith(":");
 
     if (has_net || has_drive) {
-      if ((++pos != e) && is_separator((*pos)[0])) {
+      if ((++pos != e) && is_separator((*pos)[0], style)) {
         // {C:/,//net/}, so get the first two components.
         return path.substr(0, b->size() + pos->size());
       } else {
@@ -381,7 +370,7 @@ StringRef root_path(StringRef path) {
     }
 
     // POSIX style root directory.
-    if (is_separator((*b)[0])) {
+    if (is_separator((*b)[0], style)) {
       return *b;
     }
   }
@@ -389,17 +378,12 @@ StringRef root_path(StringRef path) {
   return StringRef();
 }
 
-StringRef root_name(StringRef path) {
-  const_iterator b = begin(path),
-                 e = end(path);
+StringRef root_name(StringRef path, Style style) {
+  const_iterator b = begin(path, style), e = end(path);
   if (b != e) {
-    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
-    bool has_drive =
-#ifdef LLVM_ON_WIN32
-      b->endswith(":");
-#else
-      false;
-#endif
+    bool has_net =
+        b->size() > 2 && is_separator((*b)[0], style) && (*b)[1] == (*b)[0];
+    bool has_drive = (real_style(style) == Style::windows) && b->endswith(":");
 
     if (has_net || has_drive) {
       // just {C:,//net}, return the first component.
@@ -411,27 +395,21 @@ StringRef root_name(StringRef path) {
   return StringRef();
 }
 
-StringRef root_directory(StringRef path) {
-  const_iterator b = begin(path),
-                 pos = b,
-                 e = end(path);
+StringRef root_directory(StringRef path, Style style) {
+  const_iterator b = begin(path, style), pos = b, e = end(path);
   if (b != e) {
-    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
-    bool has_drive =
-#ifdef LLVM_ON_WIN32
-      b->endswith(":");
-#else
-      false;
-#endif
+    bool has_net =
+        b->size() > 2 && is_separator((*b)[0], style) && (*b)[1] == (*b)[0];
+    bool has_drive = (real_style(style) == Style::windows) && b->endswith(":");
 
     if ((has_net || has_drive) &&
         // {C:,//net}, skip to the next component.
-        (++pos != e) && is_separator((*pos)[0])) {
+        (++pos != e) && is_separator((*pos)[0], style)) {
       return *pos;
     }
 
     // POSIX style root directory.
-    if (!has_net && is_separator((*b)[0])) {
+    if (!has_net && is_separator((*b)[0], style)) {
       return *b;
     }
   }
@@ -440,15 +418,13 @@ StringRef root_directory(StringRef path) {
   return StringRef();
 }
 
-StringRef relative_path(StringRef path) {
-  StringRef root = root_path(path);
+StringRef relative_path(StringRef path, Style style) {
+  StringRef root = root_path(path, style);
   return path.substr(root.size());
 }
 
-void append(SmallVectorImpl<char> &path, const Twine &a,
-                                         const Twine &b,
-                                         const Twine &c,
-                                         const Twine &d) {
+void append(SmallVectorImpl<char> &path, Style style, const Twine &a,
+            const Twine &b, const Twine &c, const Twine &d) {
   SmallString<32> a_storage;
   SmallString<32> b_storage;
   SmallString<32> c_storage;
@@ -461,13 +437,15 @@ void append(SmallVectorImpl<char> &path, const Twine &a,
   if (!d.isTriviallyEmpty()) components.push_back(d.toStringRef(d_storage));
 
   for (auto &component : components) {
-    bool path_has_sep = !path.empty() && is_separator(path[path.size() - 1]);
-    bool component_has_sep = !component.empty() && is_separator(component[0]);
-    bool is_root_name = has_root_name(component);
+    bool path_has_sep =
+        !path.empty() && is_separator(path[path.size() - 1], style);
+    bool component_has_sep =
+        !component.empty() && is_separator(component[0], style);
+    bool is_root_name = has_root_name(component, style);
 
     if (path_has_sep) {
       // Strip separators from beginning of component.
-      size_t loc = component.find_first_not_of(separators);
+      size_t loc = component.find_first_not_of(separators(style));
       StringRef c = component.substr(loc);
 
       // Append it.
@@ -477,41 +455,47 @@ void append(SmallVectorImpl<char> &path, const Twine &a,
 
     if (!component_has_sep && !(path.empty() || is_root_name)) {
       // Add a separator.
-      path.push_back(preferred_separator);
+      path.push_back(preferred_separator(style));
     }
 
     path.append(component.begin(), component.end());
   }
 }
 
-void append(SmallVectorImpl<char> &path,
-            const_iterator begin, const_iterator end) {
+void append(SmallVectorImpl<char> &path, const Twine &a, const Twine &b,
+            const Twine &c, const Twine &d) {
+  append(path, Style::native, a, b, c, d);
+}
+
+void append(SmallVectorImpl<char> &path, const_iterator begin,
+            const_iterator end, Style style) {
   for (; begin != end; ++begin)
-    path::append(path, *begin);
+    path::append(path, style, *begin);
 }
 
-StringRef parent_path(StringRef path) {
-  size_t end_pos = parent_path_end(path);
+StringRef parent_path(StringRef path, Style style) {
+  size_t end_pos = parent_path_end(path, style);
   if (end_pos == StringRef::npos)
     return StringRef();
   else
     return path.substr(0, end_pos);
 }
 
-void remove_filename(SmallVectorImpl<char> &path) {
-  size_t end_pos = parent_path_end(StringRef(path.begin(), path.size()));
+void remove_filename(SmallVectorImpl<char> &path, Style style) {
+  size_t end_pos = parent_path_end(StringRef(path.begin(), path.size()), style);
   if (end_pos != StringRef::npos)
     path.set_size(end_pos);
 }
 
-void replace_extension(SmallVectorImpl<char> &path, const Twine &extension) {
+void replace_extension(SmallVectorImpl<char> &path, const Twine &extension,
+                       Style style) {
   StringRef p(path.begin(), path.size());
   SmallString<32> ext_storage;
   StringRef ext = extension.toStringRef(ext_storage);
 
   // Erase existing extension.
   size_t pos = p.find_last_of('.');
-  if (pos != StringRef::npos && pos >= filename_pos(p))
+  if (pos != StringRef::npos && pos >= filename_pos(p, style))
     path.set_size(pos);
 
   // Append '.' if needed.
@@ -523,8 +507,8 @@ void replace_extension(SmallVectorImpl<char> &path, const Twine &extension) {
 }
 
 void replace_path_prefix(SmallVectorImpl<char> &Path,
-                         const StringRef &OldPrefix,
-                         const StringRef &NewPrefix) {
+                         const StringRef &OldPrefix, const StringRef &NewPrefix,
+                         Style style) {
   if (OldPrefix.empty() && NewPrefix.empty())
     return;
 
@@ -540,53 +524,58 @@ void replace_path_prefix(SmallVectorImpl<char> &Path,
 
   StringRef RelPath = OrigPath.substr(OldPrefix.size());
   SmallString<256> NewPath;
-  path::append(NewPath, NewPrefix);
-  path::append(NewPath, RelPath);
+  path::append(NewPath, style, NewPrefix);
+  path::append(NewPath, style, RelPath);
   Path.swap(NewPath);
 }
 
-void native(const Twine &path, SmallVectorImpl<char> &result) {
+void native(const Twine &path, SmallVectorImpl<char> &result, Style style) {
   assert((!path.isSingleStringRef() ||
           path.getSingleStringRef().data() != result.data()) &&
          "path and result are not allowed to overlap!");
   // Clear result.
   result.clear();
   path.toVector(result);
-  native(result);
+  native(result, style);
 }
 
-void native(SmallVectorImpl<char> &Path) {
-#ifdef LLVM_ON_WIN32
-  std::replace(Path.begin(), Path.end(), '/', '\\');
-#else
-  for (auto PI = Path.begin(), PE = Path.end(); PI < PE; ++PI) {
-    if (*PI == '\\') {
-      auto PN = PI + 1;
-      if (PN < PE && *PN == '\\')
-        ++PI; // increment once, the for loop will move over the escaped slash
-      else
-        *PI = '/';
+void native(SmallVectorImpl<char> &Path, Style style) {
+  if (Path.empty())
+    return;
+  if (real_style(style) == Style::windows) {
+    std::replace(Path.begin(), Path.end(), '/', '\\');
+    if (Path[0] == '~' && (Path.size() == 1 || is_separator(Path[1], style))) {
+      SmallString<128> PathHome;
+      home_directory(PathHome);
+      PathHome.append(Path.begin() + 1, Path.end());
+      Path = PathHome;
+    }
+  } else {
+    for (auto PI = Path.begin(), PE = Path.end(); PI < PE; ++PI) {
+      if (*PI == '\\') {
+        auto PN = PI + 1;
+        if (PN < PE && *PN == '\\')
+          ++PI; // increment once, the for loop will move over the escaped slash
+        else
+          *PI = '/';
+      }
     }
   }
-#endif
 }
 
-std::string convert_to_slash(StringRef path) {
-#ifdef LLVM_ON_WIN32
+std::string convert_to_slash(StringRef path, Style style) {
+  if (real_style(style) != Style::windows)
+    return path;
+
   std::string s = path.str();
   std::replace(s.begin(), s.end(), '\\', '/');
   return s;
-#else
-  return path;
-#endif
 }
 
-StringRef filename(StringRef path) {
-  return *rbegin(path);
-}
+StringRef filename(StringRef path, Style style) { return *rbegin(path, style); }
 
-StringRef stem(StringRef path) {
-  StringRef fname = filename(path);
+StringRef stem(StringRef path, Style style) {
+  StringRef fname = filename(path, style);
   size_t pos = fname.find_last_of('.');
   if (pos == StringRef::npos)
     return fname;
@@ -598,8 +587,8 @@ StringRef stem(StringRef path) {
       return fname.substr(0, pos);
 }
 
-StringRef extension(StringRef path) {
-  StringRef fname = filename(path);
+StringRef extension(StringRef path, Style style) {
+  StringRef fname = filename(path, style);
   size_t pos = fname.find_last_of('.');
   if (pos == StringRef::npos)
     return StringRef();
@@ -611,110 +600,109 @@ StringRef extension(StringRef path) {
       return fname.substr(pos);
 }
 
-bool is_separator(char value) {
-  switch(value) {
-#ifdef LLVM_ON_WIN32
-    case '\\': // fall through
-#endif
-    case '/': return true;
-    default: return false;
-  }
+bool is_separator(char value, Style style) {
+  if (value == '/')
+    return true;
+  if (real_style(style) == Style::windows)
+    return value == '\\';
+  return false;
 }
 
-static const char preferred_separator_string[] = { preferred_separator, '\0' };
-
-StringRef get_separator() {
-  return preferred_separator_string;
+StringRef get_separator(Style style) {
+  if (real_style(style) == Style::windows)
+    return "\\";
+  return "/";
 }
 
-bool has_root_name(const Twine &path) {
+bool has_root_name(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !root_name(p).empty();
+  return !root_name(p, style).empty();
 }
 
-bool has_root_directory(const Twine &path) {
+bool has_root_directory(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !root_directory(p).empty();
+  return !root_directory(p, style).empty();
 }
 
-bool has_root_path(const Twine &path) {
+bool has_root_path(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !root_path(p).empty();
+  return !root_path(p, style).empty();
 }
 
-bool has_relative_path(const Twine &path) {
+bool has_relative_path(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !relative_path(p).empty();
+  return !relative_path(p, style).empty();
 }
 
-bool has_filename(const Twine &path) {
+bool has_filename(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !filename(p).empty();
+  return !filename(p, style).empty();
 }
 
-bool has_parent_path(const Twine &path) {
+bool has_parent_path(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !parent_path(p).empty();
+  return !parent_path(p, style).empty();
 }
 
-bool has_stem(const Twine &path) {
+bool has_stem(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !stem(p).empty();
+  return !stem(p, style).empty();
 }
 
-bool has_extension(const Twine &path) {
+bool has_extension(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  return !extension(p).empty();
+  return !extension(p, style).empty();
 }
 
-bool is_absolute(const Twine &path) {
+bool is_absolute(const Twine &path, Style style) {
   SmallString<128> path_storage;
   StringRef p = path.toStringRef(path_storage);
 
-  bool rootDir = has_root_directory(p),
-#ifdef LLVM_ON_WIN32
-       rootName = has_root_name(p);
-#else
-       rootName = true;
-#endif
+  bool rootDir = has_root_directory(p, style);
+  bool rootName =
+      (real_style(style) != Style::windows) || has_root_name(p, style);
 
   return rootDir && rootName;
 }
 
-bool is_relative(const Twine &path) { return !is_absolute(path); }
+bool is_relative(const Twine &path, Style style) {
+  return !is_absolute(path, style);
+}
 
-StringRef remove_leading_dotslash(StringRef Path) {
+StringRef remove_leading_dotslash(StringRef Path, Style style) {
   // Remove leading "./" (or ".//" or "././" etc.)
-  while (Path.size() > 2 && Path[0] == '.' && is_separator(Path[1])) {
+  while (Path.size() > 2 && Path[0] == '.' && is_separator(Path[1], style)) {
     Path = Path.substr(2);
-    while (Path.size() > 0 && is_separator(Path[0]))
+    while (Path.size() > 0 && is_separator(Path[0], style))
       Path = Path.substr(1);
   }
   return Path;
 }
 
-static SmallString<256> remove_dots(StringRef path, bool remove_dot_dot) {
+static SmallString<256> remove_dots(StringRef path, bool remove_dot_dot,
+                                    Style style) {
   SmallVector<StringRef, 16> components;
 
   // Skip the root path, then look for traversal in the components.
-  StringRef rel = path::relative_path(path);
-  for (StringRef C : llvm::make_range(path::begin(rel), path::end(rel))) {
+  StringRef rel = path::relative_path(path, style);
+  for (StringRef C :
+       llvm::make_range(path::begin(rel, style), path::end(rel))) {
     if (C == ".")
       continue;
     // Leading ".." will remain in the path unless it's at the root.
@@ -723,22 +711,23 @@ static SmallString<256> remove_dots(StringRef path, bool remove_dot_dot) {
         components.pop_back();
         continue;
       }
-      if (path::is_absolute(path))
+      if (path::is_absolute(path, style))
         continue;
     }
     components.push_back(C);
   }
 
-  SmallString<256> buffer = path::root_path(path);
+  SmallString<256> buffer = path::root_path(path, style);
   for (StringRef C : components)
-    path::append(buffer, C);
+    path::append(buffer, style, C);
   return buffer;
 }
 
-bool remove_dots(SmallVectorImpl<char> &path, bool remove_dot_dot) {
+bool remove_dots(SmallVectorImpl<char> &path, bool remove_dot_dot,
+                 Style style) {
   StringRef p(path.data(), path.size());
 
-  SmallString<256> result = remove_dots(p, remove_dot_dot);
+  SmallString<256> result = remove_dots(p, remove_dot_dot, style);
   if (result == path)
     return false;
 
@@ -776,7 +765,7 @@ createTemporaryFile(const Twine &Model, int &ResultFD,
                     llvm::SmallVectorImpl<char> &ResultPath, FSEntity Type) {
   SmallString<128> Storage;
   StringRef P = Model.toNullTerminatedStringRef(Storage);
-  assert(P.find_first_of(separators) == StringRef::npos &&
+  assert(P.find_first_of(separators(Style::native)) == StringRef::npos &&
          "Model must be a simple filename.");
   // Use P.begin() so that createUniqueEntity doesn't need to recreate Storage.
   return createUniqueEntity(P.begin(), ResultFD, ResultPath,
@@ -818,12 +807,9 @@ static std::error_code make_absolute(const Twine &current_directory,
                                      bool use_current_directory) {
   StringRef p(path.data(), path.size());
 
-  bool rootDirectory = path::has_root_directory(p),
-#ifdef LLVM_ON_WIN32
-       rootName = path::has_root_name(p);
-#else
-       rootName = true;
-#endif
+  bool rootDirectory = path::has_root_directory(p);
+  bool rootName =
+      (real_style(Style::native) != Style::windows) || path::has_root_name(p);
 
   // Already absolute.
   if (rootName && rootDirectory)
@@ -937,6 +923,36 @@ std::error_code copy_file(const Twine &From, const Twine &To) {
   return std::error_code();
 }
 
+ErrorOr<MD5::MD5Result> md5_contents(int FD) {
+  MD5 Hash;
+
+  constexpr size_t BufSize = 4096;
+  std::vector<uint8_t> Buf(BufSize);
+  int BytesRead = 0;
+  for (;;) {
+    BytesRead = read(FD, Buf.data(), BufSize);
+    if (BytesRead <= 0)
+      break;
+    Hash.update(makeArrayRef(Buf.data(), BytesRead));
+  }
+
+  if (BytesRead < 0)
+    return std::error_code(errno, std::generic_category());
+  MD5::MD5Result Result;
+  Hash.final(Result);
+  return Result;
+}
+
+ErrorOr<MD5::MD5Result> md5_contents(const Twine &Path) {
+  int FD;
+  if (auto EC = openFileForRead(Path, FD))
+    return EC;
+
+  auto Result = md5_contents(FD);
+  close(FD);
+  return Result;
+}
+
 bool exists(file_status status) {
   return status_known(status) && status.type() != file_type::file_not_found;
 }
@@ -945,6 +961,13 @@ bool status_known(file_status s) {
   return s.type() != file_type::status_error;
 }
 
+file_type get_file_type(const Twine &Path, bool Follow) {
+  file_status st;
+  if (status(Path, st, Follow))
+    return file_type::status_error;
+  return st.type();
+}
+
 bool is_directory(file_status status) {
   return status.type() == file_type::directory_file;
 }
@@ -969,6 +992,18 @@ std::error_code is_regular_file(const Twine &path, bool &result) {
   return std::error_code();
 }
 
+bool is_symlink_file(file_status status) {
+  return status.type() == file_type::symlink_file;
+}
+
+std::error_code is_symlink_file(const Twine &path, bool &result) {
+  file_status st;
+  if (std::error_code ec = status(path, st, false))
+    return ec;
+  result = is_symlink_file(st);
+  return std::error_code();
+}
+
 bool is_other(file_status status) {
   return exists(status) &&
          !is_regular_file(status) &&
@@ -990,179 +1025,16 @@ void directory_entry::replace_filename(const Twine &filename, file_status st) {
   Status = st;
 }
 
-template <size_t N>
-static bool startswith(StringRef Magic, const char (&S)[N]) {
-  return Magic.startswith(StringRef(S, N - 1));
-}
-
-/// @brief Identify the magic in magic.
-file_magic identify_magic(StringRef Magic) {
-  if (Magic.size() < 4)
-    return file_magic::unknown;
-  switch ((unsigned char)Magic[0]) {
-    case 0x00: {
-      // COFF bigobj, CL.exe's LTO object file, or short import library file
-      if (startswith(Magic, "\0\0\xFF\xFF")) {
-        size_t MinSize = offsetof(COFF::BigObjHeader, UUID) + sizeof(COFF::BigObjMagic);
-        if (Magic.size() < MinSize)
-          return file_magic::coff_import_library;
-
-        const char *Start = Magic.data() + offsetof(COFF::BigObjHeader, UUID);
-        if (memcmp(Start, COFF::BigObjMagic, sizeof(COFF::BigObjMagic)) == 0)
-          return file_magic::coff_object;
-        if (memcmp(Start, COFF::ClGlObjMagic, sizeof(COFF::BigObjMagic)) == 0)
-          return file_magic::coff_cl_gl_object;
-        return file_magic::coff_import_library;
-      }
-      // Windows resource file
-      if (startswith(Magic, "\0\0\0\0\x20\0\0\0\xFF"))
-        return file_magic::windows_resource;
-      // 0x0000 = COFF unknown machine type
-      if (Magic[1] == 0)
-        return file_magic::coff_object;
-      if (startswith(Magic, "\0asm"))
-        return file_magic::wasm_object;
-      break;
-    }
-    case 0xDE:  // 0x0B17C0DE = BC wraper
-      if (startswith(Magic, "\xDE\xC0\x17\x0B"))
-        return file_magic::bitcode;
-      break;
-    case 'B':
-      if (startswith(Magic, "BC\xC0\xDE"))
-        return file_magic::bitcode;
-      break;
-    case '!':
-      if (startswith(Magic, "!<arch>\n") || startswith(Magic, "!<thin>\n"))
-        return file_magic::archive;
-      break;
-
-    case '\177':
-      if (startswith(Magic, "\177ELF") && Magic.size() >= 18) {
-        bool Data2MSB = Magic[5] == 2;
-        unsigned high = Data2MSB ? 16 : 17;
-        unsigned low  = Data2MSB ? 17 : 16;
-        if (Magic[high] == 0) {
-          switch (Magic[low]) {
-            default: return file_magic::elf;
-            case 1: return file_magic::elf_relocatable;
-            case 2: return file_magic::elf_executable;
-            case 3: return file_magic::elf_shared_object;
-            case 4: return file_magic::elf_core;
-          }
-        }
-        // It's still some type of ELF file.
-        return file_magic::elf;
-      }
-      break;
-
-    case 0xCA:
-      if (startswith(Magic, "\xCA\xFE\xBA\xBE") ||
-          startswith(Magic, "\xCA\xFE\xBA\xBF")) {
-        // This is complicated by an overlap with Java class files.
-        // See the Mach-O section in /usr/share/file/magic for details.
-        if (Magic.size() >= 8 && Magic[7] < 43)
-          return file_magic::macho_universal_binary;
-      }
-      break;
-
-      // The two magic numbers for mach-o are:
-      // 0xfeedface - 32-bit mach-o
-      // 0xfeedfacf - 64-bit mach-o
-    case 0xFE:
-    case 0xCE:
-    case 0xCF: {
-      uint16_t type = 0;
-      if (startswith(Magic, "\xFE\xED\xFA\xCE") ||
-          startswith(Magic, "\xFE\xED\xFA\xCF")) {
-        /* Native endian */
-        size_t MinSize;
-        if (Magic[3] == char(0xCE))
-          MinSize = sizeof(MachO::mach_header);
-        else
-          MinSize = sizeof(MachO::mach_header_64);
-        if (Magic.size() >= MinSize)
-          type = Magic[12] << 24 | Magic[13] << 12 | Magic[14] << 8 | Magic[15];
-      } else if (startswith(Magic, "\xCE\xFA\xED\xFE") ||
-                 startswith(Magic, "\xCF\xFA\xED\xFE")) {
-        /* Reverse endian */
-        size_t MinSize;
-        if (Magic[0] == char(0xCE))
-          MinSize = sizeof(MachO::mach_header);
-        else
-          MinSize = sizeof(MachO::mach_header_64);
-        if (Magic.size() >= MinSize)
-          type = Magic[15] << 24 | Magic[14] << 12 |Magic[13] << 8 | Magic[12];
-      }
-      switch (type) {
-        default: break;
-        case 1: return file_magic::macho_object;
-        case 2: return file_magic::macho_executable;
-        case 3: return file_magic::macho_fixed_virtual_memory_shared_lib;
-        case 4: return file_magic::macho_core;
-        case 5: return file_magic::macho_preload_executable;
-        case 6: return file_magic::macho_dynamically_linked_shared_lib;
-        case 7: return file_magic::macho_dynamic_linker;
-        case 8: return file_magic::macho_bundle;
-        case 9: return file_magic::macho_dynamically_linked_shared_lib_stub;
-        case 10: return file_magic::macho_dsym_companion;
-        case 11: return file_magic::macho_kext_bundle;
-      }
-      break;
-    }
-    case 0xF0: // PowerPC Windows
-    case 0x83: // Alpha 32-bit
-    case 0x84: // Alpha 64-bit
-    case 0x66: // MPS R4000 Windows
-    case 0x50: // mc68K
-    case 0x4c: // 80386 Windows
-    case 0xc4: // ARMNT Windows
-      if (Magic[1] == 0x01)
-        return file_magic::coff_object;
-
-    case 0x90: // PA-RISC Windows
-    case 0x68: // mc68K Windows
-      if (Magic[1] == 0x02)
-        return file_magic::coff_object;
-      break;
-
-    case 'M': // Possible MS-DOS stub on Windows PE file
-      if (startswith(Magic, "MZ")) {
-        uint32_t off = read32le(Magic.data() + 0x3c);
-        // PE/COFF file, either EXE or DLL.
-        if (off < Magic.size() &&
-            memcmp(Magic.data()+off, COFF::PEMagic, sizeof(COFF::PEMagic)) == 0)
-          return file_magic::pecoff_executable;
-      }
-      break;
-
-    case 0x64: // x86-64 Windows.
-      if (Magic[1] == char(0x86))
-        return file_magic::coff_object;
-      break;
-
-    default:
-      break;
-  }
-  return file_magic::unknown;
+std::error_code directory_entry::status(file_status &result) const {
+  return fs::status(Path, result, FollowSymlinks);
 }
 
-std::error_code identify_magic(const Twine &Path, file_magic &Result) {
-  int FD;
-  if (std::error_code EC = openFileForRead(Path, FD))
+ErrorOr<perms> getPermissions(const Twine &Path) {
+  file_status Status;
+  if (std::error_code EC = status(Path, Status))
     return EC;
 
-  char Buffer[32];
-  int Length = read(FD, Buffer, sizeof(Buffer));
-  if (close(FD) != 0 || Length < 0)
-    return std::error_code(errno, std::generic_category());
-
-  Result = identify_magic(StringRef(Buffer, Length));
-  return std::error_code();
-}
-
-std::error_code directory_entry::status(file_status &result) const {
-  return fs::status(Path, result);
+  return Status.permissions();
 }
 
 } // end namespace fs