Create a HostThread abstraction.

This patch moves creates a thread abstraction that represents a
thread running inside the LLDB process.  This is a replacement for
otherwise using lldb::thread_t, and provides a platform agnostic
interface to managing these threads.

Differential Revision: http://reviews.llvm.org/D5198

Reviewed by: Jim Ingham

llvm-svn: 217460

lldb/source/Host/windows/ThisThread.cpp

@@ -0,0 +1,60 @@
+//===-- ThisThread.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/Error.h"
+
+#include "lldb/Host/windows/windows.h"
+#include "lldb/Host/ThisThread.h"
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+namespace
+{
+static const DWORD MS_VC_EXCEPTION = 0x406D1388;
+
+#pragma pack(push, 8)
+struct THREADNAME_INFO
+{
+    DWORD dwType;     // Must be 0x1000.
+    LPCSTR szName;    // Pointer to thread name
+    DWORD dwThreadId; // Thread ID (-1 == current thread)
+    DWORD dwFlags;    // Reserved.  Do not use.
+};
+#pragma pack(pop)
+}
+
+void
+ThisThread::SetName(llvm::StringRef name)
+{
+// Other compilers don't yet support SEH, so we can only set the thread if compiling with MSVC.
+// TODO(zturner): Once clang-cl supports SEH, relax this conditional.
+#if defined(_MSC_VER)
+    THREADNAME_INFO info;
+    info.dwType = 0x1000;
+    info.szName = name.data();
+    info.dwThreadId = ::GetCurrentThreadId();
+    info.dwFlags = 0;
+
+    __try { ::RaiseException(MS_VC_EXCEPTION, 0, sizeof(info) / sizeof(ULONG_PTR), (ULONG_PTR *)&info); }
+    __except(EXCEPTION_EXECUTE_HANDLER) {}
+#endif
+}
+
+void
+ThisThread::GetName(llvm::SmallVectorImpl<char> &name)
+{
+    // Getting the thread name is not supported on Windows.
+    // TODO(zturner): In SetName(), make a TLS entry that contains the thread's name, and in this function
+    // try to extract that TLS entry.
+    name.clear();
+}