Here's the patch to provide dbgs(). By default it works just like errs().
When -debug-buffer-size=N (N > 0) is set, it buffers output sent to it and
dumps it at program termination via a signal handler.
Please review. Thanks!
-Dave
Index: include/llvm/Support/Debug.h
==================================================================---
include/llvm/Support/Debug.h (revision 91557)
+++ include/llvm/Support/Debug.h (working copy)
@@ -28,6 +28,8 @@
namespace llvm {
+class raw_ostream;
+
/// DEBUG_TYPE macro - Files can specify a DEBUG_TYPE as a string, which
causes
/// all of their DEBUG statements to be activatable with
-debug-only=thatstring.
#ifndef DEBUG_TYPE
@@ -72,15 +74,20 @@
#define DEBUG_WITH_TYPE(TYPE, X) do { } while (0)
#endif
+/// dbgs() - This returns a reference to a raw_ostream for debugging
+/// messages. If debugging is disabled it returns errs(). Use it
+/// like: dbgs() << "foo" << "bar";
+raw_ostream &dbgs();
+
// DEBUG macro - This macro should be used by passes to emit debug
information.
// In the '-debug' option is specified on the commandline, and if this
is a
// debug build, then the code specified as the option to the macro will be
// executed. Otherwise it will not be. Example:
//
-// DEBUG(errs() << "Bitset contains: " << Bitset <<
"\n");
+// DEBUG(dbgs() << "Bitset contains: " << Bitset <<
"\n");
//
#define DEBUG(X) DEBUG_WITH_TYPE(DEBUG_TYPE, X)
-
+
} // End llvm namespace
#endif
Index: lib/Support/Debug.cpp
==================================================================---
lib/Support/Debug.cpp (revision 91557)
+++ lib/Support/Debug.cpp (working copy)
@@ -25,6 +25,9 @@
#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.
@@ -37,6 +40,15 @@
Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
cl::location(DebugFlag));
+// -debug-buffer-size - This is a command line op0tion to set the size
+// of the debug stream circular buffer. The value is the number of
+// characters to save.
+static cl::opt<unsigned>
+DebugBufferSize("debug-buffer-size",
+ llvm::cl::desc("Save last N characters of debug output
"
+ "[default 0--immediate print-out]"),
+ llvm::cl::init(0));
+
static std::string CurrentDebugType;
static struct DebugOnlyOpt {
void operator=(const std::string &Val) const {
@@ -50,6 +62,16 @@
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)
+{
+ llvm::circular_raw_ostream *logout +
dynamic_cast<llvm::circular_raw_ostream *>(&llvm::dbgs());
+ if (logout) {
+ logout->dumpLog();
+ }
+}
+
// 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.
@@ -66,9 +88,29 @@
CurrentDebugType = Type;
}
+/// dbgs - Return a circular-buffered debug stream.
+raw_ostream &llvm::dbgs() {
+ static circular_raw_ostream strm(errs(), DebugBufferSize);
+
+ static bool initialized = false;
+ if (!initialized) {
+ initialized = true;
+
+ sys::AddSignalHandler(&debug_user_sig_handler, 0);
+ // TODO: Add a handler for SIGUSER1-type signals so the user can
+ // force a debug dump.
+ }
+
+ return strm;
+}
+
#else
// Avoid "has no symbols" warning.
namespace llvm {
-int Debug_dummy = 0;
+ /// dbgs - Return errs().
+ raw_ostream &dbgs() {
+ return errs();
+ }
}
+
#endif
On Dec 17, 2009, at 4:02 PM, David Greene wrote:> Here's the patch to provide dbgs(). By default it works just like > errs(). > When -debug-buffer-size=N (N > 0) is set, it buffers output sent to > it and > dumps it at program termination via a signal handler. > > Please review. Thanks! > > -Dave > > Index: include/llvm/Support/Debug.h > ==================================================================> --- include/llvm/Support/Debug.h (revision 91557)Ok.> +++ lib/Support/Debug.cpp (working copy) > @@ -25,6 +25,9 @@ > > #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. > @@ -37,6 +40,15 @@ > Debug("debug", cl::desc("Enable debug output"), cl::Hidden, > cl::location(DebugFlag)); > > +// -debug-buffer-size - This is a command line op0tion to set the > size > +// of the debug stream circular buffer. The value is the number of > +// characters to save. > +static cl::opt<unsigned> > +DebugBufferSize("debug-buffer-size", > + llvm::cl::desc("Save last N characters of debug > output "How about "Buffer the last N characters of debug output until program termination". This should probably also be cl::Hidden.> +// Signal handlers - dump debug output on termination. > +static void debug_user_sig_handler(void *Cookie) > +{ > + llvm::circular_raw_ostream *logout > + dynamic_cast<llvm::circular_raw_ostream *>(&llvm::dbgs());Please do not use dynamic_cast, we're trying to eliminate the last RTTI use in the compiler.> +/// dbgs - Return a circular-buffered debug stream. > +raw_ostream &llvm::dbgs() { > + static circular_raw_ostream strm(errs(), DebugBufferSize); > + > + static bool initialized = false; > + if (!initialized) { > + initialized = true;This isn't thread safe. A way to fix this is to do something like: static struct dbgstream { circular_raw_ostream strm; dbgstream() : strm(errs(), DebugBufferSize) { your one time init stuff here. } } thestrm; return thestrm.strm; Please commit with the appropriate fixes when we settle on the stream design. -Chris
On Friday 18 December 2009 19:56, Chris Lattner wrote:> > +// -debug-buffer-size - This is a command line op0tion to set the > > size > > +// of the debug stream circular buffer. The value is the number of > > +// characters to save. > > +static cl::opt<unsigned> > > +DebugBufferSize("debug-buffer-size", > > + llvm::cl::desc("Save last N characters of debug > > output " > > How about "Buffer the last N characters of debug output until program > termination". This should probably also be cl::Hidden.Ok.> > +// Signal handlers - dump debug output on termination. > > +static void debug_user_sig_handler(void *Cookie) > > +{ > > + llvm::circular_raw_ostream *logout > > + dynamic_cast<llvm::circular_raw_ostream *>(&llvm::dbgs()); > > Please do not use dynamic_cast, we're trying to eliminate the last > RTTI use in the compiler.Do you want me to use dyn_cast? That means I'll have to add some more stuff to raw_ostream and circular_raw_ostream. Or I think I can just assume (Yikes!) that if the signal handler is invoked it will really be a circular_raw_ostream since the handler should (!) only be set up in debug mode. That scares me a bit, though.> > +/// dbgs - Return a circular-buffered debug stream. > > +raw_ostream &llvm::dbgs() { > > + static circular_raw_ostream strm(errs(), DebugBufferSize); > > + > > + static bool initialized = false; > > + if (!initialized) { > > + initialized = true; > > This isn't thread safe. A way to fix this is to do something like: > > static struct dbgstream { > circular_raw_ostream strm; > > dbgstream() : strm(errs(), DebugBufferSize) { > your one time init stuff here. > } > } thestrm; > > return thestrm.strm;Ok.> Please commit with the appropriate fixes when we settle on the stream > design.All right. -Dave