Allow multiple debug types in --debug-only

[christof]

Summary

The --debug-only option now takes a comma separated list of debug types. This means that the DEBUG_TYPE cannot take a comma anymore. All existing passes conform to this rule.

[MatzeB]

Note that you can already pass -debug-only multiple times to enable output for multiple debug types. Though I guess the variant with commas may be easier to discover.

[christof]

In D15645#315088, @MatzeB wrote:

Note that you can already pass -debug-only multiple times to enable output for multiple debug types. Though I guess the variant with commas may be easier to discover.

Yes, I know. I did not change that behaviour. But while debugging the compiler, I found it much easier to add and remove ,pass then to add --debug-only=pass. It is even worse when your input is a C source. That requires the extra -mllvm argument to clang. For that reason I wrote this small patch.

Would this be accepted?

[MatzeB]

Shouldn't hurt and improve usability for developers. LGTM.

docs/ProgrammersManual.rst

.. code-block:: none
   <no output>
   $ opt < a.bc > /dev/null -mypass -debug
   'foo' debug type
   'bar' debug type
   $ opt < a.bc > /dev/null -mypass -debug-only=foo
   'foo' debug type
   $ opt < a.bc > /dev/null -mypass -debug-only=bar
   'bar' debug type
+  $ opt < a.bc > /dev/null -mypass -debug-only=foo,bar
+  'foo' debug type
+  'bar' debug type
 
 Of course, in practice, you should only set ``DEBUG_TYPE`` at the top of a file,
 to specify the debug type for the entire module. Be careful that you only do
 this after including Debug.h and not around any #include of headers. Also, you
 should use names more meaningful than "foo" and "bar", because there is no
 system in place to ensure that names do not conflict. If two different modules
 use the same string, they will all be turned on when the name is specified.
 This allows, for example, all debug information for instruction scheduling to be
 enabled with ``-debug-only=InstrSched``, even if the source lives in multiple
-files.
+files. The name must not include a comma (,) as that is used to seperate the
+arguments of the ``-debug-only`` option.
 
 For performance reasons, -debug-only is not available in optimized build
 (``--enable-optimized``) of LLVM.
 
 The ``DEBUG_WITH_TYPE`` macro is also available for situations where you would
 like to set ``DEBUG_TYPE``, but only for one specific ``DEBUG`` statement.  It
 takes an additional first parameter, which is the type to use.  For example, the
 preceding example could be written as:

lib/Support/Debug.cpp

 
 namespace {
 
 struct DebugOnlyOpt {
   void operator=(const std::string &Val) const {
     if (Val.empty())
       return;
     DebugFlag = true;
-    CurrentDebugType->push_back(Val);
+    SmallVector<StringRef,8> dbgTypes;
+    StringRef(Val).split(dbgTypes, ',', -1, false);
+    for (auto dbgType : dbgTypes)
+      CurrentDebugType->push_back(dbgType);
   }
 };
 
 }
 
 static DebugOnlyOpt DebugOnlyOptLoc;
 
 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
-DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"),
+DebugOnly("debug-only", cl::desc("Enable a specific type of debug output (comma separated list of types)"),
           cl::Hidden, cl::ZeroOrMore, 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() ==