Check in LLVM r95781.
diff --git a/lib/Support/Debug.cpp b/lib/Support/Debug.cpp
new file mode 100644
index 0000000..82b4b8c
--- /dev/null
+++ b/lib/Support/Debug.cpp
@@ -0,0 +1,128 @@
+//===-- Debug.cpp - An easy way to add debug output to your code ----------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a handle way of adding debugging information to your
+// code, without it being enabled all of the time, and without having to add
+// command line options to enable it.
+//
+// In particular, just wrap your code with the DEBUG() macro, and it will be
+// enabled automatically if you specify '-debug' on the command-line.
+// Alternatively, you can also use the SET_DEBUG_TYPE("foo") macro to specify
+// that your debug code belongs to class "foo". Then, on the command line, you
+// can specify '-debug-only=foo' to enable JUST the debug information for the
+// foo class.
+//
+// When compiling in release mode, the -debug-* options and all code in DEBUG()
+// statements disappears, so it does not effect the runtime of the code.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/circular_raw_ostream.h"
+#include "llvm/System/Signals.h"
+
+using namespace llvm;
+
+// All Debug.h functionality is a no-op in NDEBUG mode.
+#ifndef NDEBUG
+bool llvm::DebugFlag; // DebugFlag - Exported boolean set by the -debug option
+
+// -debug - Command line option to enable the DEBUG statements in the passes.
+// This flag may only be enabled in debug builds.
+static cl::opt<bool, true>
+Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
+ cl::location(DebugFlag));
+
+// -debug-buffer-size - Buffer the last N characters of debug output
+//until program termination.
+static cl::opt<unsigned>
+DebugBufferSize("debug-buffer-size",
+ cl::desc("Buffer the last N characters of debug output"
+ "until program termination. "
+ "[default 0 -- immediate print-out]"),
+ cl::Hidden,
+ cl::init(0));
+
+static std::string CurrentDebugType;
+static struct DebugOnlyOpt {
+ void operator=(const std::string &Val) const {
+ DebugFlag |= !Val.empty();
+ CurrentDebugType = Val;
+ }
+} DebugOnlyOptLoc;
+
+static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
+DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"),
+ cl::Hidden, cl::value_desc("debug string"),
+ cl::location(DebugOnlyOptLoc), cl::ValueRequired);
+
+// Signal handlers - dump debug output on termination.
+static void debug_user_sig_handler(void *Cookie)
+{
+ // This is a bit sneaky. Since this is under #ifndef NDEBUG, we
+ // know that debug mode is enabled and dbgs() really is a
+ // circular_raw_ostream. If NDEBUG is defined, then dbgs() ==
+ // errs() but this will never be invoked.
+ llvm::circular_raw_ostream *dbgout =
+ static_cast<llvm::circular_raw_ostream *>(&llvm::dbgs());
+ dbgout->flushBufferWithBanner();
+}
+
+// isCurrentDebugType - Return true if the specified string is the debug type
+// specified on the command line, or if none was specified on the command line
+// with the -debug-only=X option.
+//
+bool llvm::isCurrentDebugType(const char *DebugType) {
+ return CurrentDebugType.empty() || DebugType == CurrentDebugType;
+}
+
+/// SetCurrentDebugType - Set the current debug type, as if the -debug-only=X
+/// option were specified. Note that DebugFlag also needs to be set to true for
+/// debug output to be produced.
+///
+void llvm::SetCurrentDebugType(const char *Type) {
+ CurrentDebugType = Type;
+}
+
+/// dbgs - Return a circular-buffered debug stream.
+raw_ostream &llvm::dbgs() {
+ // Do one-time initialization in a thread-safe way.
+ static struct dbgstream {
+ circular_raw_ostream strm;
+
+ dbgstream() :
+ strm(errs(), "*** Debug Log Output ***\n",
+ (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) {
+ if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0)
+ // TODO: Add a handler for SIGUSER1-type signals so the user can
+ // force a debug dump.
+ sys::AddSignalHandler(&debug_user_sig_handler, 0);
+ // Otherwise we've already set the debug stream buffer size to
+ // zero, disabling buffering so it will output directly to errs().
+ }
+ } thestrm;
+
+ return thestrm.strm;
+}
+
+#else
+// Avoid "has no symbols" warning.
+namespace llvm {
+ /// dbgs - Return errs().
+ raw_ostream &dbgs() {
+ return errs();
+ }
+}
+
+#endif
+
+/// EnableDebugBuffering - Turn on signal handler installation.
+///
+bool llvm::EnableDebugBuffering = false;