Delete DataBufferMemoryMap.

After a series of patches on the LLVM side to get the mmaping
code up to compatibility with LLDB's needs, it is now ready
to go, which means LLDB's custom mmapping code is redundant.
So this patch deletes it all and uses LLVM's code instead.

In the future, we could take this one step further and delete
even the lldb DataBuffer base class and rely entirely on
LLVM's facilities, but this is a job for another day.

Differential Revision: https://reviews.llvm.org/D30054

llvm-svn: 296159
diff --git a/lldb/source/Core/DataBufferLLVM.cpp b/lldb/source/Core/DataBufferLLVM.cpp
new file mode 100644
index 0000000..e427658
--- /dev/null
+++ b/lldb/source/Core/DataBufferLLVM.cpp
@@ -0,0 +1,58 @@
+//===--- DataBufferLLVM.cpp -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Core/DataBufferLLVM.h"
+
+#include "lldb/Host/FileSpec.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace lldb_private;
+
+DataBufferLLVM::DataBufferLLVM(std::unique_ptr<llvm::MemoryBuffer> MemBuffer)
+    : Buffer(std::move(MemBuffer)) {
+  assert(Buffer != nullptr &&
+         "Cannot construct a DataBufferLLVM with a null buffer");
+}
+
+DataBufferLLVM::~DataBufferLLVM() {}
+
+std::shared_ptr<DataBufferLLVM>
+DataBufferLLVM::CreateFromPath(llvm::StringRef Path, uint64_t Size,
+                               uint64_t Offset) {
+  // If the file resides non-locally, pass the volatile flag so that we don't
+  // mmap it.
+  bool Volatile = !llvm::sys::fs::is_local(Path);
+
+  auto Buffer = llvm::MemoryBuffer::getFileSlice(Path, Size, Offset, Volatile);
+  if (!Buffer)
+    return nullptr;
+  return std::shared_ptr<DataBufferLLVM>(
+      new DataBufferLLVM(std::move(*Buffer)));
+}
+
+std::shared_ptr<DataBufferLLVM>
+DataBufferLLVM::CreateFromFileSpec(const FileSpec &F, uint64_t Size,
+                                   uint64_t Offset) {
+  return CreateFromPath(F.GetPath(), Size, Offset);
+}
+
+uint8_t *DataBufferLLVM::GetBytes() {
+  return const_cast<uint8_t *>(GetBuffer());
+}
+
+const uint8_t *DataBufferLLVM::GetBytes() const { return GetBuffer(); }
+
+lldb::offset_t DataBufferLLVM::GetByteSize() const {
+  return Buffer->getBufferSize();
+}
+
+const uint8_t *DataBufferLLVM::GetBuffer() const {
+  return reinterpret_cast<const uint8_t *>(Buffer->getBufferStart());
+}