Restoring authorship annotation for <[email protected]>. Commit 1 of 2.

1 files changed, 539 insertions, 539 deletions

diff --git a/contrib/libs/llvm12/lib/Support/MemoryBuffer.cpp b/contrib/libs/llvm12/lib/Support/MemoryBuffer.cpp
index 248fb72c496..f421396f8d6 100644
--- a/contrib/libs/llvm12/lib/Support/MemoryBuffer.cpp
+++ b/contrib/libs/llvm12/lib/Support/MemoryBuffer.cpp
@@ -1,539 +1,539 @@
-//===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-//  This file implements the MemoryBuffer interface.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Support/MemoryBuffer.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/Config/config.h"
-#include "llvm/Support/Errc.h"
-#include "llvm/Support/Errno.h"
-#include "llvm/Support/FileSystem.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/Path.h"
-#include "llvm/Support/Process.h"
-#include "llvm/Support/Program.h"
-#include "llvm/Support/SmallVectorMemoryBuffer.h"
-#include <cassert>
-#include <cerrno>
-#include <cstring>
-#include <new>
-#include <sys/types.h>
-#include <system_error>
-#if !defined(_MSC_VER) && !defined(__MINGW32__)
-#include <unistd.h>
-#else
-#include <io.h>
-#endif
-using namespace llvm;
-
-//===----------------------------------------------------------------------===//
-// MemoryBuffer implementation itself.
-//===----------------------------------------------------------------------===//
-
-MemoryBuffer::~MemoryBuffer() { }
-
-/// init - Initialize this MemoryBuffer as a reference to externally allocated
-/// memory, memory that we know is already null terminated.
-void MemoryBuffer::init(const char *BufStart, const char *BufEnd,
-                        bool RequiresNullTerminator) {
-  assert((!RequiresNullTerminator || BufEnd[0] == 0) &&
-         "Buffer is not null terminated!");
-  BufferStart = BufStart;
-  BufferEnd = BufEnd;
-}
-
-//===----------------------------------------------------------------------===//
-// MemoryBufferMem implementation.
-//===----------------------------------------------------------------------===//
-
-/// CopyStringRef - Copies contents of a StringRef into a block of memory and
-/// null-terminates it.
-static void CopyStringRef(char *Memory, StringRef Data) {
-  if (!Data.empty())
-    memcpy(Memory, Data.data(), Data.size());
-  Memory[Data.size()] = 0; // Null terminate string.
-}
-
-namespace {
-struct NamedBufferAlloc {
-  const Twine &Name;
-  NamedBufferAlloc(const Twine &Name) : Name(Name) {}
-};
-}
-
-void *operator new(size_t N, const NamedBufferAlloc &Alloc) {
-  SmallString<256> NameBuf;
-  StringRef NameRef = Alloc.Name.toStringRef(NameBuf);
-
-  char *Mem = static_cast<char *>(operator new(N + NameRef.size() + 1));
-  CopyStringRef(Mem + N, NameRef);
-  return Mem;
-}
-
-namespace {
-/// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory.
-template<typename MB>
-class MemoryBufferMem : public MB {
-public:
-  MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) {
-    MemoryBuffer::init(InputData.begin(), InputData.end(),
-                       RequiresNullTerminator);
-  }
-
-  /// Disable sized deallocation for MemoryBufferMem, because it has
-  /// tail-allocated data.
-  void operator delete(void *p) { ::operator delete(p); }
-
-  StringRef getBufferIdentifier() const override {
-    // The name is stored after the class itself.
-    return StringRef(reinterpret_cast<const char *>(this + 1));
-  }
-
-  MemoryBuffer::BufferKind getBufferKind() const override {
-    return MemoryBuffer::MemoryBuffer_Malloc;
-  }
-};
-}
-
-template <typename MB>
-static ErrorOr<std::unique_ptr<MB>>
-getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize,
-           uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile);
-
-std::unique_ptr<MemoryBuffer>
-MemoryBuffer::getMemBuffer(StringRef InputData, StringRef BufferName,
-                           bool RequiresNullTerminator) {
-  auto *Ret = new (NamedBufferAlloc(BufferName))
-      MemoryBufferMem<MemoryBuffer>(InputData, RequiresNullTerminator);
-  return std::unique_ptr<MemoryBuffer>(Ret);
-}
-
-std::unique_ptr<MemoryBuffer>
-MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) {
-  return std::unique_ptr<MemoryBuffer>(getMemBuffer(
-      Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator));
-}
-
-static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
-getMemBufferCopyImpl(StringRef InputData, const Twine &BufferName) {
-  auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(InputData.size(), BufferName);
-  if (!Buf)
-    return make_error_code(errc::not_enough_memory);
-  memcpy(Buf->getBufferStart(), InputData.data(), InputData.size());
-  return std::move(Buf);
-}
-
-std::unique_ptr<MemoryBuffer>
-MemoryBuffer::getMemBufferCopy(StringRef InputData, const Twine &BufferName) {
-  auto Buf = getMemBufferCopyImpl(InputData, BufferName);
-  if (Buf)
-    return std::move(*Buf);
-  return nullptr;
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getFileOrSTDIN(const Twine &Filename, int64_t FileSize,
-                             bool RequiresNullTerminator) {
-  SmallString<256> NameBuf;
-  StringRef NameRef = Filename.toStringRef(NameBuf);
-
-  if (NameRef == "-")
-    return getSTDIN();
-  return getFile(Filename, FileSize, RequiresNullTerminator);
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getFileSlice(const Twine &FilePath, uint64_t MapSize,
-                           uint64_t Offset, bool IsVolatile) {
-  return getFileAux<MemoryBuffer>(FilePath, -1, MapSize, Offset, false,
-                                  IsVolatile);
-}
-
-//===----------------------------------------------------------------------===//
-// MemoryBuffer::getFile implementation.
-//===----------------------------------------------------------------------===//
-
-namespace {
-
-template <typename MB>
-constexpr sys::fs::mapped_file_region::mapmode Mapmode =
-    sys::fs::mapped_file_region::readonly;
-template <>
-constexpr sys::fs::mapped_file_region::mapmode Mapmode<MemoryBuffer> =
-    sys::fs::mapped_file_region::readonly;
-template <>
-constexpr sys::fs::mapped_file_region::mapmode Mapmode<WritableMemoryBuffer> =
-    sys::fs::mapped_file_region::priv;
-template <>
-constexpr sys::fs::mapped_file_region::mapmode
-    Mapmode<WriteThroughMemoryBuffer> = sys::fs::mapped_file_region::readwrite;
-
-/// Memory maps a file descriptor using sys::fs::mapped_file_region.
-///
-/// This handles converting the offset into a legal offset on the platform.
-template<typename MB>
-class MemoryBufferMMapFile : public MB {
-  sys::fs::mapped_file_region MFR;
-
-  static uint64_t getLegalMapOffset(uint64_t Offset) {
-    return Offset & ~(sys::fs::mapped_file_region::alignment() - 1);
-  }
-
-  static uint64_t getLegalMapSize(uint64_t Len, uint64_t Offset) {
-    return Len + (Offset - getLegalMapOffset(Offset));
-  }
-
-  const char *getStart(uint64_t Len, uint64_t Offset) {
-    return MFR.const_data() + (Offset - getLegalMapOffset(Offset));
-  }
-
-public:
-  MemoryBufferMMapFile(bool RequiresNullTerminator, sys::fs::file_t FD, uint64_t Len,
-                       uint64_t Offset, std::error_code &EC)
-      : MFR(FD, Mapmode<MB>, getLegalMapSize(Len, Offset),
-            getLegalMapOffset(Offset), EC) {
-    if (!EC) {
-      const char *Start = getStart(Len, Offset);
-      MemoryBuffer::init(Start, Start + Len, RequiresNullTerminator);
-    }
-  }
-
-  /// Disable sized deallocation for MemoryBufferMMapFile, because it has
-  /// tail-allocated data.
-  void operator delete(void *p) { ::operator delete(p); }
-
-  StringRef getBufferIdentifier() const override {
-    // The name is stored after the class itself.
-    return StringRef(reinterpret_cast<const char *>(this + 1));
-  }
-
-  MemoryBuffer::BufferKind getBufferKind() const override {
-    return MemoryBuffer::MemoryBuffer_MMap;
-  }
-};
-}
-
-static ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
-getMemoryBufferForStream(sys::fs::file_t FD, const Twine &BufferName) {
-  const ssize_t ChunkSize = 4096*4;
-  SmallString<ChunkSize> Buffer;
-  // Read into Buffer until we hit EOF.
-  for (;;) {
-    Buffer.reserve(Buffer.size() + ChunkSize);
-    Expected<size_t> ReadBytes = sys::fs::readNativeFile(
-        FD, makeMutableArrayRef(Buffer.end(), ChunkSize));
-    if (!ReadBytes)
-      return errorToErrorCode(ReadBytes.takeError());
-    if (*ReadBytes == 0)
-      break;
-    Buffer.set_size(Buffer.size() + *ReadBytes);
-  }
-
-  return getMemBufferCopyImpl(Buffer, BufferName);
-}
-
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getFile(const Twine &Filename, int64_t FileSize,
-                      bool RequiresNullTerminator, bool IsVolatile) {
-  return getFileAux<MemoryBuffer>(Filename, FileSize, FileSize, 0,
-                                  RequiresNullTerminator, IsVolatile);
-}
-
-template <typename MB>
-static ErrorOr<std::unique_ptr<MB>>
-getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
-                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
-                bool IsVolatile);
-
-template <typename MB>
-static ErrorOr<std::unique_ptr<MB>>
-getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize,
-           uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile) {
-  Expected<sys::fs::file_t> FDOrErr =
-      sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None);
-  if (!FDOrErr)
-    return errorToErrorCode(FDOrErr.takeError());
-  sys::fs::file_t FD = *FDOrErr;
-  auto Ret = getOpenFileImpl<MB>(FD, Filename, FileSize, MapSize, Offset,
-                                 RequiresNullTerminator, IsVolatile);
-  sys::fs::closeFile(FD);
-  return Ret;
-}
-
-ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
-WritableMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize,
-                              bool IsVolatile) {
-  return getFileAux<WritableMemoryBuffer>(Filename, FileSize, FileSize, 0,
-                                          /*RequiresNullTerminator*/ false,
-                                          IsVolatile);
-}
-
-ErrorOr<std::unique_ptr<WritableMemoryBuffer>>
-WritableMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
-                                   uint64_t Offset, bool IsVolatile) {
-  return getFileAux<WritableMemoryBuffer>(Filename, -1, MapSize, Offset, false,
-                                          IsVolatile);
-}
-
-std::unique_ptr<WritableMemoryBuffer>
-WritableMemoryBuffer::getNewUninitMemBuffer(size_t Size, const Twine &BufferName) {
-  using MemBuffer = MemoryBufferMem<WritableMemoryBuffer>;
-  // Allocate space for the MemoryBuffer, the data and the name. It is important
-  // that MemoryBuffer and data are aligned so PointerIntPair works with them.
-  // TODO: Is 16-byte alignment enough?  We copy small object files with large
-  // alignment expectations into this buffer.
-  SmallString<256> NameBuf;
-  StringRef NameRef = BufferName.toStringRef(NameBuf);
-  size_t AlignedStringLen = alignTo(sizeof(MemBuffer) + NameRef.size() + 1, 16);
-  size_t RealLen = AlignedStringLen + Size + 1;
-  char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow));
-  if (!Mem)
-    return nullptr;
-
-  // The name is stored after the class itself.
-  CopyStringRef(Mem + sizeof(MemBuffer), NameRef);
-
-  // The buffer begins after the name and must be aligned.
-  char *Buf = Mem + AlignedStringLen;
-  Buf[Size] = 0; // Null terminate buffer.
-
-  auto *Ret = new (Mem) MemBuffer(StringRef(Buf, Size), true);
-  return std::unique_ptr<WritableMemoryBuffer>(Ret);
-}
-
-std::unique_ptr<WritableMemoryBuffer>
-WritableMemoryBuffer::getNewMemBuffer(size_t Size, const Twine &BufferName) {
-  auto SB = WritableMemoryBuffer::getNewUninitMemBuffer(Size, BufferName);
-  if (!SB)
-    return nullptr;
-  memset(SB->getBufferStart(), 0, Size);
-  return SB;
-}
-
-static bool shouldUseMmap(sys::fs::file_t FD,
-                          size_t FileSize,
-                          size_t MapSize,
-                          off_t Offset,
-                          bool RequiresNullTerminator,
-                          int PageSize,
-                          bool IsVolatile) {
-  // mmap may leave the buffer without null terminator if the file size changed
-  // by the time the last page is mapped in, so avoid it if the file size is
-  // likely to change.
-  if (IsVolatile && RequiresNullTerminator)
-    return false;
-
-  // We don't use mmap for small files because this can severely fragment our
-  // address space.
-  if (MapSize < 4 * 4096 || MapSize < (unsigned)PageSize)
-    return false;
-
-  if (!RequiresNullTerminator)
-    return true;
-
-  // If we don't know the file size, use fstat to find out.  fstat on an open
-  // file descriptor is cheaper than stat on a random path.
-  // FIXME: this chunk of code is duplicated, but it avoids a fstat when
-  // RequiresNullTerminator = false and MapSize != -1.
-  if (FileSize == size_t(-1)) {
-    sys::fs::file_status Status;
-    if (sys::fs::status(FD, Status))
-      return false;
-    FileSize = Status.getSize();
-  }
-
-  // If we need a null terminator and the end of the map is inside the file,
-  // we cannot use mmap.
-  size_t End = Offset + MapSize;
-  assert(End <= FileSize);
-  if (End != FileSize)
-    return false;
-
-  // Don't try to map files that are exactly a multiple of the system page size
-  // if we need a null terminator.
-  if ((FileSize & (PageSize -1)) == 0)
-    return false;
-
-#if defined(__CYGWIN__)
-  // Don't try to map files that are exactly a multiple of the physical page size
-  // if we need a null terminator.
-  // FIXME: We should reorganize again getPageSize() on Win32.
-  if ((FileSize & (4096 - 1)) == 0)
-    return false;
-#endif
-
-  return true;
-}
-
-static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
-getReadWriteFile(const Twine &Filename, uint64_t FileSize, uint64_t MapSize,
-                 uint64_t Offset) {
-  Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForReadWrite(
-      Filename, sys::fs::CD_OpenExisting, sys::fs::OF_None);
-  if (!FDOrErr)
-    return errorToErrorCode(FDOrErr.takeError());
-  sys::fs::file_t FD = *FDOrErr;
-
-  // Default is to map the full file.
-  if (MapSize == uint64_t(-1)) {
-    // If we don't know the file size, use fstat to find out.  fstat on an open
-    // file descriptor is cheaper than stat on a random path.
-    if (FileSize == uint64_t(-1)) {
-      sys::fs::file_status Status;
-      std::error_code EC = sys::fs::status(FD, Status);
-      if (EC)
-        return EC;
-
-      // If this not a file or a block device (e.g. it's a named pipe
-      // or character device), we can't mmap it, so error out.
-      sys::fs::file_type Type = Status.type();
-      if (Type != sys::fs::file_type::regular_file &&
-          Type != sys::fs::file_type::block_file)
-        return make_error_code(errc::invalid_argument);
-
-      FileSize = Status.getSize();
-    }
-    MapSize = FileSize;
-  }
-
-  std::error_code EC;
-  std::unique_ptr<WriteThroughMemoryBuffer> Result(
-      new (NamedBufferAlloc(Filename))
-          MemoryBufferMMapFile<WriteThroughMemoryBuffer>(false, FD, MapSize,
-                                                         Offset, EC));
-  if (EC)
-    return EC;
-  return std::move(Result);
-}
-
-ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
-WriteThroughMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize) {
-  return getReadWriteFile(Filename, FileSize, FileSize, 0);
-}
-
-/// Map a subrange of the specified file as a WritableMemoryBuffer.
-ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>>
-WriteThroughMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize,
-                                       uint64_t Offset) {
-  return getReadWriteFile(Filename, -1, MapSize, Offset);
-}
-
-template <typename MB>
-static ErrorOr<std::unique_ptr<MB>>
-getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
-                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator,
-                bool IsVolatile) {
-  static int PageSize = sys::Process::getPageSizeEstimate();
-
-  // Default is to map the full file.
-  if (MapSize == uint64_t(-1)) {
-    // If we don't know the file size, use fstat to find out.  fstat on an open
-    // file descriptor is cheaper than stat on a random path.
-    if (FileSize == uint64_t(-1)) {
-      sys::fs::file_status Status;
-      std::error_code EC = sys::fs::status(FD, Status);
-      if (EC)
-        return EC;
-
-      // If this not a file or a block device (e.g. it's a named pipe
-      // or character device), we can't trust the size. Create the memory
-      // buffer by copying off the stream.
-      sys::fs::file_type Type = Status.type();
-      if (Type != sys::fs::file_type::regular_file &&
-          Type != sys::fs::file_type::block_file)
-        return getMemoryBufferForStream(FD, Filename);
-
-      FileSize = Status.getSize();
-    }
-    MapSize = FileSize;
-  }
-
-  if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator,
-                    PageSize, IsVolatile)) {
-    std::error_code EC;
-    std::unique_ptr<MB> Result(
-        new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>(
-            RequiresNullTerminator, FD, MapSize, Offset, EC));
-    if (!EC)
-      return std::move(Result);
-  }
-
-  auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(MapSize, Filename);
-  if (!Buf) {
-    // Failed to create a buffer. The only way it can fail is if
-    // new(std::nothrow) returns 0.
-    return make_error_code(errc::not_enough_memory);
-  }
-
-  // Read until EOF, zero-initialize the rest.
-  MutableArrayRef<char> ToRead = Buf->getBuffer();
-  while (!ToRead.empty()) {
-    Expected<size_t> ReadBytes =
-        sys::fs::readNativeFileSlice(FD, ToRead, Offset);
-    if (!ReadBytes)
-      return errorToErrorCode(ReadBytes.takeError());
-    if (*ReadBytes == 0) {
-      std::memset(ToRead.data(), 0, ToRead.size());
-      break;
-    }
-    ToRead = ToRead.drop_front(*ReadBytes);
-    Offset += *ReadBytes;
-  }
-
-  return std::move(Buf);
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize,
-                          bool RequiresNullTerminator, bool IsVolatile) {
-  return getOpenFileImpl<MemoryBuffer>(FD, Filename, FileSize, FileSize, 0,
-                         RequiresNullTerminator, IsVolatile);
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize,
-                               int64_t Offset, bool IsVolatile) {
-  assert(MapSize != uint64_t(-1));
-  return getOpenFileImpl<MemoryBuffer>(FD, Filename, -1, MapSize, Offset, false,
-                                       IsVolatile);
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() {
-  // Read in all of the data from stdin, we cannot mmap stdin.
-  //
-  // FIXME: That isn't necessarily true, we should try to mmap stdin and
-  // fallback if it fails.
-  sys::ChangeStdinToBinary();
-
-  return getMemoryBufferForStream(sys::fs::getStdinHandle(), "<stdin>");
-}
-
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-MemoryBuffer::getFileAsStream(const Twine &Filename) {
-  Expected<sys::fs::file_t> FDOrErr =
-      sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None);
-  if (!FDOrErr)
-    return errorToErrorCode(FDOrErr.takeError());
-  sys::fs::file_t FD = *FDOrErr;
-  ErrorOr<std::unique_ptr<MemoryBuffer>> Ret =
-      getMemoryBufferForStream(FD, Filename);
-  sys::fs::closeFile(FD);
-  return Ret;
-}
-
-MemoryBufferRef MemoryBuffer::getMemBufferRef() const {
-  StringRef Data = getBuffer();
-  StringRef Identifier = getBufferIdentifier();
-  return MemoryBufferRef(Data, Identifier);
-}
-
-SmallVectorMemoryBuffer::~SmallVectorMemoryBuffer() {}
+//===--- MemoryBuffer.cpp - Memory Buffer implementation ------------------===// 
+// 
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
+// See https://llvm.org/LICENSE.txt for license information. 
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
+// 
+//===----------------------------------------------------------------------===// 
+// 
+//  This file implements the MemoryBuffer interface. 
+// 
+//===----------------------------------------------------------------------===// 
+ 
+#include "llvm/Support/MemoryBuffer.h" 
+#include "llvm/ADT/SmallString.h" 
+#include "llvm/Config/config.h" 
+#include "llvm/Support/Errc.h" 
+#include "llvm/Support/Errno.h" 
+#include "llvm/Support/FileSystem.h" 
+#include "llvm/Support/MathExtras.h" 
+#include "llvm/Support/Path.h" 
+#include "llvm/Support/Process.h" 
+#include "llvm/Support/Program.h" 
+#include "llvm/Support/SmallVectorMemoryBuffer.h" 
+#include <cassert> 
+#include <cerrno> 
+#include <cstring> 
+#include <new> 
+#include <sys/types.h> 
+#include <system_error> 
+#if !defined(_MSC_VER) && !defined(__MINGW32__) 
+#include <unistd.h> 
+#else 
+#include <io.h> 
+#endif 
+using namespace llvm; 
+ 
+//===----------------------------------------------------------------------===// 
+// MemoryBuffer implementation itself. 
+//===----------------------------------------------------------------------===// 
+ 
+MemoryBuffer::~MemoryBuffer() { } 
+ 
+/// init - Initialize this MemoryBuffer as a reference to externally allocated 
+/// memory, memory that we know is already null terminated. 
+void MemoryBuffer::init(const char *BufStart, const char *BufEnd, 
+                        bool RequiresNullTerminator) { 
+  assert((!RequiresNullTerminator || BufEnd[0] == 0) && 
+         "Buffer is not null terminated!"); 
+  BufferStart = BufStart; 
+  BufferEnd = BufEnd; 
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// MemoryBufferMem implementation. 
+//===----------------------------------------------------------------------===// 
+ 
+/// CopyStringRef - Copies contents of a StringRef into a block of memory and 
+/// null-terminates it. 
+static void CopyStringRef(char *Memory, StringRef Data) { 
+  if (!Data.empty()) 
+    memcpy(Memory, Data.data(), Data.size()); 
+  Memory[Data.size()] = 0; // Null terminate string. 
+} 
+ 
+namespace { 
+struct NamedBufferAlloc { 
+  const Twine &Name; 
+  NamedBufferAlloc(const Twine &Name) : Name(Name) {} 
+}; 
+} 
+ 
+void *operator new(size_t N, const NamedBufferAlloc &Alloc) { 
+  SmallString<256> NameBuf; 
+  StringRef NameRef = Alloc.Name.toStringRef(NameBuf); 
+ 
+  char *Mem = static_cast<char *>(operator new(N + NameRef.size() + 1)); 
+  CopyStringRef(Mem + N, NameRef); 
+  return Mem; 
+} 
+ 
+namespace { 
+/// MemoryBufferMem - Named MemoryBuffer pointing to a block of memory. 
+template<typename MB> 
+class MemoryBufferMem : public MB { 
+public: 
+  MemoryBufferMem(StringRef InputData, bool RequiresNullTerminator) { 
+    MemoryBuffer::init(InputData.begin(), InputData.end(), 
+                       RequiresNullTerminator); 
+  } 
+ 
+  /// Disable sized deallocation for MemoryBufferMem, because it has 
+  /// tail-allocated data. 
+  void operator delete(void *p) { ::operator delete(p); } 
+ 
+  StringRef getBufferIdentifier() const override { 
+    // The name is stored after the class itself. 
+    return StringRef(reinterpret_cast<const char *>(this + 1)); 
+  } 
+ 
+  MemoryBuffer::BufferKind getBufferKind() const override { 
+    return MemoryBuffer::MemoryBuffer_Malloc; 
+  } 
+}; 
+} 
+ 
+template <typename MB> 
+static ErrorOr<std::unique_ptr<MB>> 
+getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize, 
+           uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile); 
+ 
+std::unique_ptr<MemoryBuffer> 
+MemoryBuffer::getMemBuffer(StringRef InputData, StringRef BufferName, 
+                           bool RequiresNullTerminator) { 
+  auto *Ret = new (NamedBufferAlloc(BufferName)) 
+      MemoryBufferMem<MemoryBuffer>(InputData, RequiresNullTerminator); 
+  return std::unique_ptr<MemoryBuffer>(Ret); 
+} 
+ 
+std::unique_ptr<MemoryBuffer> 
+MemoryBuffer::getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator) { 
+  return std::unique_ptr<MemoryBuffer>(getMemBuffer( 
+      Ref.getBuffer(), Ref.getBufferIdentifier(), RequiresNullTerminator)); 
+} 
+ 
+static ErrorOr<std::unique_ptr<WritableMemoryBuffer>> 
+getMemBufferCopyImpl(StringRef InputData, const Twine &BufferName) { 
+  auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(InputData.size(), BufferName); 
+  if (!Buf) 
+    return make_error_code(errc::not_enough_memory); 
+  memcpy(Buf->getBufferStart(), InputData.data(), InputData.size()); 
+  return std::move(Buf); 
+} 
+ 
+std::unique_ptr<MemoryBuffer> 
+MemoryBuffer::getMemBufferCopy(StringRef InputData, const Twine &BufferName) { 
+  auto Buf = getMemBufferCopyImpl(InputData, BufferName); 
+  if (Buf) 
+    return std::move(*Buf); 
+  return nullptr; 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getFileOrSTDIN(const Twine &Filename, int64_t FileSize, 
+                             bool RequiresNullTerminator) { 
+  SmallString<256> NameBuf; 
+  StringRef NameRef = Filename.toStringRef(NameBuf); 
+ 
+  if (NameRef == "-") 
+    return getSTDIN(); 
+  return getFile(Filename, FileSize, RequiresNullTerminator); 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getFileSlice(const Twine &FilePath, uint64_t MapSize, 
+                           uint64_t Offset, bool IsVolatile) { 
+  return getFileAux<MemoryBuffer>(FilePath, -1, MapSize, Offset, false, 
+                                  IsVolatile); 
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// MemoryBuffer::getFile implementation. 
+//===----------------------------------------------------------------------===// 
+ 
+namespace { 
+ 
+template <typename MB> 
+constexpr sys::fs::mapped_file_region::mapmode Mapmode = 
+    sys::fs::mapped_file_region::readonly; 
+template <> 
+constexpr sys::fs::mapped_file_region::mapmode Mapmode<MemoryBuffer> = 
+    sys::fs::mapped_file_region::readonly; 
+template <> 
+constexpr sys::fs::mapped_file_region::mapmode Mapmode<WritableMemoryBuffer> = 
+    sys::fs::mapped_file_region::priv; 
+template <> 
+constexpr sys::fs::mapped_file_region::mapmode 
+    Mapmode<WriteThroughMemoryBuffer> = sys::fs::mapped_file_region::readwrite; 
+ 
+/// Memory maps a file descriptor using sys::fs::mapped_file_region. 
+/// 
+/// This handles converting the offset into a legal offset on the platform. 
+template<typename MB> 
+class MemoryBufferMMapFile : public MB { 
+  sys::fs::mapped_file_region MFR; 
+ 
+  static uint64_t getLegalMapOffset(uint64_t Offset) { 
+    return Offset & ~(sys::fs::mapped_file_region::alignment() - 1); 
+  } 
+ 
+  static uint64_t getLegalMapSize(uint64_t Len, uint64_t Offset) { 
+    return Len + (Offset - getLegalMapOffset(Offset)); 
+  } 
+ 
+  const char *getStart(uint64_t Len, uint64_t Offset) { 
+    return MFR.const_data() + (Offset - getLegalMapOffset(Offset)); 
+  } 
+ 
+public: 
+  MemoryBufferMMapFile(bool RequiresNullTerminator, sys::fs::file_t FD, uint64_t Len, 
+                       uint64_t Offset, std::error_code &EC) 
+      : MFR(FD, Mapmode<MB>, getLegalMapSize(Len, Offset), 
+            getLegalMapOffset(Offset), EC) { 
+    if (!EC) { 
+      const char *Start = getStart(Len, Offset); 
+      MemoryBuffer::init(Start, Start + Len, RequiresNullTerminator); 
+    } 
+  } 
+ 
+  /// Disable sized deallocation for MemoryBufferMMapFile, because it has 
+  /// tail-allocated data. 
+  void operator delete(void *p) { ::operator delete(p); } 
+ 
+  StringRef getBufferIdentifier() const override { 
+    // The name is stored after the class itself. 
+    return StringRef(reinterpret_cast<const char *>(this + 1)); 
+  } 
+ 
+  MemoryBuffer::BufferKind getBufferKind() const override { 
+    return MemoryBuffer::MemoryBuffer_MMap; 
+  } 
+}; 
+} 
+ 
+static ErrorOr<std::unique_ptr<WritableMemoryBuffer>> 
+getMemoryBufferForStream(sys::fs::file_t FD, const Twine &BufferName) { 
+  const ssize_t ChunkSize = 4096*4; 
+  SmallString<ChunkSize> Buffer; 
+  // Read into Buffer until we hit EOF. 
+  for (;;) { 
+    Buffer.reserve(Buffer.size() + ChunkSize); 
+    Expected<size_t> ReadBytes = sys::fs::readNativeFile( 
+        FD, makeMutableArrayRef(Buffer.end(), ChunkSize)); 
+    if (!ReadBytes) 
+      return errorToErrorCode(ReadBytes.takeError()); 
+    if (*ReadBytes == 0) 
+      break; 
+    Buffer.set_size(Buffer.size() + *ReadBytes); 
+  } 
+ 
+  return getMemBufferCopyImpl(Buffer, BufferName); 
+} 
+ 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getFile(const Twine &Filename, int64_t FileSize, 
+                      bool RequiresNullTerminator, bool IsVolatile) { 
+  return getFileAux<MemoryBuffer>(Filename, FileSize, FileSize, 0, 
+                                  RequiresNullTerminator, IsVolatile); 
+} 
+ 
+template <typename MB> 
+static ErrorOr<std::unique_ptr<MB>> 
+getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, 
+                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator, 
+                bool IsVolatile); 
+ 
+template <typename MB> 
+static ErrorOr<std::unique_ptr<MB>> 
+getFileAux(const Twine &Filename, int64_t FileSize, uint64_t MapSize, 
+           uint64_t Offset, bool RequiresNullTerminator, bool IsVolatile) { 
+  Expected<sys::fs::file_t> FDOrErr = 
+      sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None); 
+  if (!FDOrErr) 
+    return errorToErrorCode(FDOrErr.takeError()); 
+  sys::fs::file_t FD = *FDOrErr; 
+  auto Ret = getOpenFileImpl<MB>(FD, Filename, FileSize, MapSize, Offset, 
+                                 RequiresNullTerminator, IsVolatile); 
+  sys::fs::closeFile(FD); 
+  return Ret; 
+} 
+ 
+ErrorOr<std::unique_ptr<WritableMemoryBuffer>> 
+WritableMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize, 
+                              bool IsVolatile) { 
+  return getFileAux<WritableMemoryBuffer>(Filename, FileSize, FileSize, 0, 
+                                          /*RequiresNullTerminator*/ false, 
+                                          IsVolatile); 
+} 
+ 
+ErrorOr<std::unique_ptr<WritableMemoryBuffer>> 
+WritableMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize, 
+                                   uint64_t Offset, bool IsVolatile) { 
+  return getFileAux<WritableMemoryBuffer>(Filename, -1, MapSize, Offset, false, 
+                                          IsVolatile); 
+} 
+ 
+std::unique_ptr<WritableMemoryBuffer> 
+WritableMemoryBuffer::getNewUninitMemBuffer(size_t Size, const Twine &BufferName) { 
+  using MemBuffer = MemoryBufferMem<WritableMemoryBuffer>; 
+  // Allocate space for the MemoryBuffer, the data and the name. It is important 
+  // that MemoryBuffer and data are aligned so PointerIntPair works with them. 
+  // TODO: Is 16-byte alignment enough?  We copy small object files with large 
+  // alignment expectations into this buffer. 
+  SmallString<256> NameBuf; 
+  StringRef NameRef = BufferName.toStringRef(NameBuf); 
+  size_t AlignedStringLen = alignTo(sizeof(MemBuffer) + NameRef.size() + 1, 16); 
+  size_t RealLen = AlignedStringLen + Size + 1; 
+  char *Mem = static_cast<char*>(operator new(RealLen, std::nothrow)); 
+  if (!Mem) 
+    return nullptr; 
+ 
+  // The name is stored after the class itself. 
+  CopyStringRef(Mem + sizeof(MemBuffer), NameRef); 
+ 
+  // The buffer begins after the name and must be aligned. 
+  char *Buf = Mem + AlignedStringLen; 
+  Buf[Size] = 0; // Null terminate buffer. 
+ 
+  auto *Ret = new (Mem) MemBuffer(StringRef(Buf, Size), true); 
+  return std::unique_ptr<WritableMemoryBuffer>(Ret); 
+} 
+ 
+std::unique_ptr<WritableMemoryBuffer> 
+WritableMemoryBuffer::getNewMemBuffer(size_t Size, const Twine &BufferName) { 
+  auto SB = WritableMemoryBuffer::getNewUninitMemBuffer(Size, BufferName); 
+  if (!SB) 
+    return nullptr; 
+  memset(SB->getBufferStart(), 0, Size); 
+  return SB; 
+} 
+ 
+static bool shouldUseMmap(sys::fs::file_t FD, 
+                          size_t FileSize, 
+                          size_t MapSize, 
+                          off_t Offset, 
+                          bool RequiresNullTerminator, 
+                          int PageSize, 
+                          bool IsVolatile) { 
+  // mmap may leave the buffer without null terminator if the file size changed 
+  // by the time the last page is mapped in, so avoid it if the file size is 
+  // likely to change. 
+  if (IsVolatile && RequiresNullTerminator) 
+    return false; 
+ 
+  // We don't use mmap for small files because this can severely fragment our 
+  // address space. 
+  if (MapSize < 4 * 4096 || MapSize < (unsigned)PageSize) 
+    return false; 
+ 
+  if (!RequiresNullTerminator) 
+    return true; 
+ 
+  // If we don't know the file size, use fstat to find out.  fstat on an open 
+  // file descriptor is cheaper than stat on a random path. 
+  // FIXME: this chunk of code is duplicated, but it avoids a fstat when 
+  // RequiresNullTerminator = false and MapSize != -1. 
+  if (FileSize == size_t(-1)) { 
+    sys::fs::file_status Status; 
+    if (sys::fs::status(FD, Status)) 
+      return false; 
+    FileSize = Status.getSize(); 
+  } 
+ 
+  // If we need a null terminator and the end of the map is inside the file, 
+  // we cannot use mmap. 
+  size_t End = Offset + MapSize; 
+  assert(End <= FileSize); 
+  if (End != FileSize) 
+    return false; 
+ 
+  // Don't try to map files that are exactly a multiple of the system page size 
+  // if we need a null terminator. 
+  if ((FileSize & (PageSize -1)) == 0) 
+    return false; 
+ 
+#if defined(__CYGWIN__) 
+  // Don't try to map files that are exactly a multiple of the physical page size 
+  // if we need a null terminator. 
+  // FIXME: We should reorganize again getPageSize() on Win32. 
+  if ((FileSize & (4096 - 1)) == 0) 
+    return false; 
+#endif 
+ 
+  return true; 
+} 
+ 
+static ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>> 
+getReadWriteFile(const Twine &Filename, uint64_t FileSize, uint64_t MapSize, 
+                 uint64_t Offset) { 
+  Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForReadWrite( 
+      Filename, sys::fs::CD_OpenExisting, sys::fs::OF_None); 
+  if (!FDOrErr) 
+    return errorToErrorCode(FDOrErr.takeError()); 
+  sys::fs::file_t FD = *FDOrErr; 
+ 
+  // Default is to map the full file. 
+  if (MapSize == uint64_t(-1)) { 
+    // If we don't know the file size, use fstat to find out.  fstat on an open 
+    // file descriptor is cheaper than stat on a random path. 
+    if (FileSize == uint64_t(-1)) { 
+      sys::fs::file_status Status; 
+      std::error_code EC = sys::fs::status(FD, Status); 
+      if (EC) 
+        return EC; 
+ 
+      // If this not a file or a block device (e.g. it's a named pipe 
+      // or character device), we can't mmap it, so error out. 
+      sys::fs::file_type Type = Status.type(); 
+      if (Type != sys::fs::file_type::regular_file && 
+          Type != sys::fs::file_type::block_file) 
+        return make_error_code(errc::invalid_argument); 
+ 
+      FileSize = Status.getSize(); 
+    } 
+    MapSize = FileSize; 
+  } 
+ 
+  std::error_code EC; 
+  std::unique_ptr<WriteThroughMemoryBuffer> Result( 
+      new (NamedBufferAlloc(Filename)) 
+          MemoryBufferMMapFile<WriteThroughMemoryBuffer>(false, FD, MapSize, 
+                                                         Offset, EC)); 
+  if (EC) 
+    return EC; 
+  return std::move(Result); 
+} 
+ 
+ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>> 
+WriteThroughMemoryBuffer::getFile(const Twine &Filename, int64_t FileSize) { 
+  return getReadWriteFile(Filename, FileSize, FileSize, 0); 
+} 
+ 
+/// Map a subrange of the specified file as a WritableMemoryBuffer. 
+ErrorOr<std::unique_ptr<WriteThroughMemoryBuffer>> 
+WriteThroughMemoryBuffer::getFileSlice(const Twine &Filename, uint64_t MapSize, 
+                                       uint64_t Offset) { 
+  return getReadWriteFile(Filename, -1, MapSize, Offset); 
+} 
+ 
+template <typename MB> 
+static ErrorOr<std::unique_ptr<MB>> 
+getOpenFileImpl(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, 
+                uint64_t MapSize, int64_t Offset, bool RequiresNullTerminator, 
+                bool IsVolatile) { 
+  static int PageSize = sys::Process::getPageSizeEstimate(); 
+ 
+  // Default is to map the full file. 
+  if (MapSize == uint64_t(-1)) { 
+    // If we don't know the file size, use fstat to find out.  fstat on an open 
+    // file descriptor is cheaper than stat on a random path. 
+    if (FileSize == uint64_t(-1)) { 
+      sys::fs::file_status Status; 
+      std::error_code EC = sys::fs::status(FD, Status); 
+      if (EC) 
+        return EC; 
+ 
+      // If this not a file or a block device (e.g. it's a named pipe 
+      // or character device), we can't trust the size. Create the memory 
+      // buffer by copying off the stream. 
+      sys::fs::file_type Type = Status.type(); 
+      if (Type != sys::fs::file_type::regular_file && 
+          Type != sys::fs::file_type::block_file) 
+        return getMemoryBufferForStream(FD, Filename); 
+ 
+      FileSize = Status.getSize(); 
+    } 
+    MapSize = FileSize; 
+  } 
+ 
+  if (shouldUseMmap(FD, FileSize, MapSize, Offset, RequiresNullTerminator, 
+                    PageSize, IsVolatile)) { 
+    std::error_code EC; 
+    std::unique_ptr<MB> Result( 
+        new (NamedBufferAlloc(Filename)) MemoryBufferMMapFile<MB>( 
+            RequiresNullTerminator, FD, MapSize, Offset, EC)); 
+    if (!EC) 
+      return std::move(Result); 
+  } 
+ 
+  auto Buf = WritableMemoryBuffer::getNewUninitMemBuffer(MapSize, Filename); 
+  if (!Buf) { 
+    // Failed to create a buffer. The only way it can fail is if 
+    // new(std::nothrow) returns 0. 
+    return make_error_code(errc::not_enough_memory); 
+  } 
+ 
+  // Read until EOF, zero-initialize the rest. 
+  MutableArrayRef<char> ToRead = Buf->getBuffer(); 
+  while (!ToRead.empty()) { 
+    Expected<size_t> ReadBytes = 
+        sys::fs::readNativeFileSlice(FD, ToRead, Offset); 
+    if (!ReadBytes) 
+      return errorToErrorCode(ReadBytes.takeError()); 
+    if (*ReadBytes == 0) { 
+      std::memset(ToRead.data(), 0, ToRead.size()); 
+      break; 
+    } 
+    ToRead = ToRead.drop_front(*ReadBytes); 
+    Offset += *ReadBytes; 
+  } 
+ 
+  return std::move(Buf); 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getOpenFile(sys::fs::file_t FD, const Twine &Filename, uint64_t FileSize, 
+                          bool RequiresNullTerminator, bool IsVolatile) { 
+  return getOpenFileImpl<MemoryBuffer>(FD, Filename, FileSize, FileSize, 0, 
+                         RequiresNullTerminator, IsVolatile); 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getOpenFileSlice(sys::fs::file_t FD, const Twine &Filename, uint64_t MapSize, 
+                               int64_t Offset, bool IsVolatile) { 
+  assert(MapSize != uint64_t(-1)); 
+  return getOpenFileImpl<MemoryBuffer>(FD, Filename, -1, MapSize, Offset, false, 
+                                       IsVolatile); 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> MemoryBuffer::getSTDIN() { 
+  // Read in all of the data from stdin, we cannot mmap stdin. 
+  // 
+  // FIXME: That isn't necessarily true, we should try to mmap stdin and 
+  // fallback if it fails. 
+  sys::ChangeStdinToBinary(); 
+ 
+  return getMemoryBufferForStream(sys::fs::getStdinHandle(), "<stdin>"); 
+} 
+ 
+ErrorOr<std::unique_ptr<MemoryBuffer>> 
+MemoryBuffer::getFileAsStream(const Twine &Filename) { 
+  Expected<sys::fs::file_t> FDOrErr = 
+      sys::fs::openNativeFileForRead(Filename, sys::fs::OF_None); 
+  if (!FDOrErr) 
+    return errorToErrorCode(FDOrErr.takeError()); 
+  sys::fs::file_t FD = *FDOrErr; 
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Ret = 
+      getMemoryBufferForStream(FD, Filename); 
+  sys::fs::closeFile(FD); 
+  return Ret; 
+} 
+ 
+MemoryBufferRef MemoryBuffer::getMemBufferRef() const { 
+  StringRef Data = getBuffer(); 
+  StringRef Identifier = getBufferIdentifier(); 
+  return MemoryBufferRef(Data, Identifier); 
+} 
+ 
+SmallVectorMemoryBuffer::~SmallVectorMemoryBuffer() {}