c++: Implement a coroutine language debug dump

This provides to people working on coroutines, as well as writing tests
for coroutines, a way to have insight into the results and inputs of the
coroutine transformation passes, which is quite essential to
understanding what happens in the coroutine transformation.  Currently,
the information dumped is the pre-transform function (which is not
otherwise available), the generated ramp function, the generated frame
type, the transformed actor/resumer, and the destroyer stub.

While debugging this, I've also encountered a minor bug in
c-pretty-print.cc, where it tried to check DECL_REGISTER of DECLs that
did not support it.  I've added a check for that.

Similary, I found one in pp_cxx_template_parameter, where TREE_TYPE was
called on the list cell the template parameter was in rather than on the
parameter itself.  I've fixed that.

And, lastly, there appeared to be no way to pretty-print a FIELD_DECL,
so I added support to cxx_pretty_printer::declaration for it (by reusing
the VAR_DECL path).

Co-authored-by: Iain Sandoe <iain@sandoe.co.uk>

gcc/c-family/ChangeLog:

	* c-pretty-print.cc (c_pretty_printer::storage_class_specifier):
	Check that we're looking at a PARM_DECL or VAR_DECL before
	looking at DECL_REGISTER.

gcc/cp/ChangeLog:

	* coroutines.cc (dump_record_fields): New helper.  Iterates a
	RECORD_TYPEs TYPE_FIELDS and pretty-prints them.
	(dmp_str): New.  The lang-coro dump stream.
	(coro_dump_id): New.  ID of the lang-coro dump.
	(coro_dump_flags): New.  Flags passed to the lang-coro dump.
	(coro_maybe_dump_initial_function): New helper.  Prints, if
	dumping is enabled, the fndecl passed to it as the original
	function.
	(coro_maybe_dump_ramp): New.  Prints the ramp function passed to
	it, if dumping is enabled.
	(coro_maybe_dump_transformed_functions): New.
	(cp_coroutine_transform::apply_transforms): Initialize the
	lang-coro dump.  Call coro_maybe_dump_initial_function on the
	original function, as well as coro_maybe_dump_ramp, after the
	transformation into the ramp is finished.
	(cp_coroutine_transform::finish_transforms): Call
	coro_maybe_dump_transformed_functions on the built actor and
	destroy.
	* cp-objcp-common.cc (cp_register_dumps): Register the coroutine
	dump.
	* cp-tree.h (coro_dump_id): Declare as extern.
	* cxx-pretty-print.cc (pp_cxx_template_parameter): Don't call
	TREE_TYPE on a TREE_LIST cell.
	(cxx_pretty_printer::declaration): Handle FIELD_DECL similar to
	VAR_DECL.

gcc/ChangeLog:

	* dumpfile.cc (FIRST_ME_AUTO_NUMBERED_DUMP): Bump to 6 for sake
	of the coroutine dump.

1 files changed, 2 insertions, 1 deletions

diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
index b772d8d..c48336f 100644
--- a/gcc/c-family/c-pretty-print.cc
+++ b/gcc/c-family/c-pretty-print.cc
@@ -753,7 +753,8 @@ c_pretty_printer::storage_class_specifier (tree t)
     pp_c_ws_string (this, "typedef");
   else if (DECL_P (t))
     {
-      if (DECL_REGISTER (t))
+      if ((TREE_CODE (t) == PARM_DECL || VAR_P (t))
+	  && DECL_REGISTER (t))
 	pp_c_ws_string (this, "register");
       else if (TREE_STATIC (t) && VAR_P (t))
 	pp_c_ws_string (this, "static");