[1/2] c++: Implement a coroutine language debug dump

Message ID 20240918210202.192478-2-arsen@aarsen.me
State New
Headers
Series Support for coroutine frames with new-extended alignment |

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Commit Message

Arsen Arsenović Sept. 18, 2024, 8:36 p.m. UTC
  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.  Prints the actor
	and destroy functions passed to it, if dumping is enabled, as
	well as the frame type (inferred from the actor argument).
	(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.
---
 gcc/c-family/c-pretty-print.cc |   3 +-
 gcc/cp/coroutines.cc           | 116 +++++++++++++++++++++++++++++++++
 gcc/cp/cp-objcp-common.cc      |   2 +
 gcc/cp/cp-tree.h               |   1 +
 gcc/cp/cxx-pretty-print.cc     |   3 +-
 gcc/dumpfile.cc                |   2 +-
 6 files changed, 124 insertions(+), 3 deletions(-)
  

Patch

diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
index 26038818d759..9be0154af7ac 100644
--- a/gcc/c-family/c-pretty-print.cc
+++ b/gcc/c-family/c-pretty-print.cc
@@ -748,7 +748,8 @@  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");
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index a3edaa842d9d..416202ed3e88 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -34,6 +34,115 @@  along with GCC; see the file COPYING3.  If not see
 #include "hash-map.h"
 #include "coroutines.h"
 
+/* ================= Debug. ================= */
+
+#include "langhooks.h"
+#include "cxx-pretty-print.h"
+
+static void
+dump_record_fields (cxx_pretty_printer *pp, tree typ)
+{
+  pp->type_id (typ);
+  pp_newline_and_indent (pp, 2);
+  pp_left_brace (pp);
+  pp_indentation (pp) += 2;
+
+  /* We'll be on a new line, we don't need padding.  */
+  pp->set_padding (pp_none);
+
+  for (tree tmp = TYPE_FIELDS (typ); tmp; tmp = DECL_CHAIN (tmp))
+    {
+      pp_newline_and_indent (pp, 0);
+      pp->declaration (tmp);
+    }
+
+  pp_newline_and_indent (pp, -2);
+  pp_right_brace (pp);
+  pp_newline_and_indent (pp, -2);
+}
+
+static FILE *dmp_str = NULL;
+int coro_dump_id;
+static dump_flags_t coro_dump_flags;
+
+/* Pretty print the function FNDECL, which ought to be a coroutine before
+   co_await expansion, into the lang-coro dump, if it is enabled.  */
+
+static void
+coro_maybe_dump_initial_function (tree fndecl)
+{
+  if (!dmp_str)
+    return;
+
+  bool lambda_p = LAMBDA_TYPE_P (DECL_CONTEXT (fndecl));
+  fprintf (dmp_str, "%s %s original:\n",
+	   (lambda_p ? "Lambda" : "Function"),
+	    lang_hooks.decl_printable_name (fndecl, 2));
+
+  cxx_pretty_printer pp;
+  pp.set_output_stream (dmp_str);
+  pp.flags = coro_dump_flags;
+  pp.declaration (fndecl);
+  pp_newline_and_flush (&pp);
+}
+
+/* Pretty print the RAMP function to the lang-coro dump, if it is enabled.  */
+
+static void
+coro_maybe_dump_ramp (tree ramp)
+{
+  if (!dmp_str)
+    return;
+
+  cxx_pretty_printer pp;
+  pp.set_output_stream (dmp_str);
+  pp.flags = coro_dump_flags;
+
+  pp_string (&pp, "Ramp function:");
+  pp_newline_and_indent (&pp, 0);
+  pp.declaration (ramp);
+  pp_newline_and_flush (&pp);
+}
+
+/* For a given ACTOR, DESTROY and FRAME_TYPE, if lang-coro dumping is enabled,
+   pretty-print their contents to the lang-coro dump.  */
+
+static void
+coro_maybe_dump_transformed_functions (tree actor, tree destroy)
+{
+  if (!dmp_str)
+    return;
+
+  cxx_pretty_printer pp;
+  pp.set_output_stream (dmp_str);
+  pp.flags = coro_dump_flags;
+
+  if (!actor || actor == error_mark_node)
+    {
+      pp_string (&pp, "Transform failed");
+      pp_newline_and_flush (&pp);
+      return;
+    }
+
+  tree frame = TREE_TYPE (TREE_TYPE (DECL_ARGUMENTS (actor)));
+  pp_string (&pp, "Frame type:");
+  pp_newline (&pp);
+  dump_record_fields (&pp, frame);
+  pp_newline_and_flush (&pp);
+
+  pp_string (&pp, "Actor/resumer:");
+  pp_newline (&pp);
+  pp.declaration (actor);
+  pp_newline_and_flush (&pp);
+
+  pp_string (&pp, "Destroyer:");
+  pp_newline (&pp);
+  pp.declaration (destroy);
+  pp_newline_and_flush (&pp);
+}
+
+/* ================= END Debug. ================= */
+
 static bool coro_promise_type_found_p (tree, location_t);
 
 /* GCC C++ coroutines implementation.
@@ -5214,6 +5323,10 @@  cp_coroutine_transform::~cp_coroutine_transform ()
 void
 cp_coroutine_transform::apply_transforms ()
 {
+  if (dmp_str == NULL)
+    dmp_str = dump_begin (coro_dump_id, &coro_dump_flags);
+
+  coro_maybe_dump_initial_function (orig_fn_decl);
 
   coroutine_body
     = split_coroutine_body_from_ramp (orig_fn_decl);
@@ -5261,6 +5374,7 @@  cp_coroutine_transform::apply_transforms ()
   frame_type = finish_struct (frame_type, NULL_TREE);
 
   valid_coroutine = build_ramp_function ();
+  coro_maybe_dump_ramp (orig_fn_decl);
 }
 
 /* Having analysed and collected the necessary data we are now in a position
@@ -5279,6 +5393,8 @@  cp_coroutine_transform::finish_transforms ()
 
   current_function_decl = destroyer;
   build_destroy_fn (fn_start, frame_type, destroyer, resumer, inline_p);
+
+  coro_maybe_dump_transformed_functions (resumer, destroyer);
 }
 
 #include "gt-cp-coroutines.h"
diff --git a/gcc/cp/cp-objcp-common.cc b/gcc/cp/cp-objcp-common.cc
index cd379514991d..248119b05fe1 100644
--- a/gcc/cp/cp-objcp-common.cc
+++ b/gcc/cp/cp-objcp-common.cc
@@ -607,6 +607,8 @@  cp_register_dumps (gcc::dump_manager *dumps)
 
   raw_dump_id = dumps->dump_register
     (".raw", "lang-raw", "lang-raw", DK_lang, OPTGROUP_NONE, false);
+  coro_dump_id = dumps->dump_register
+    (".coro", "lang-coro", "lang-coro", DK_lang, OPTGROUP_NONE, false);
 }
 
 void
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 72ed4f1a4741..886b5e2b2f99 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6680,6 +6680,7 @@  extern cp_parameter_declarator *no_parameters;
 extern int class_dump_id;
 extern int module_dump_id;
 extern int raw_dump_id;
+extern int coro_dump_id;
 
 /* Whether the current context is manifestly constant-evaluated.
    Used by the constexpr machinery to control folding of
diff --git a/gcc/cp/cxx-pretty-print.cc b/gcc/cp/cxx-pretty-print.cc
index e690354e08e9..4184bb87768e 100644
--- a/gcc/cp/cxx-pretty-print.cc
+++ b/gcc/cp/cxx-pretty-print.cc
@@ -2277,7 +2277,7 @@  pp_cxx_template_parameter (cxx_pretty_printer *pp, tree t)
     {
     case TYPE_DECL:
       pp_cxx_ws_string (pp, "class");
-      if (TEMPLATE_TYPE_PARAMETER_PACK (TREE_TYPE (t)))
+      if (TEMPLATE_TYPE_PARAMETER_PACK (TREE_TYPE (parameter)))
 	pp_cxx_ws_string (pp, "...");
       if (DECL_NAME (parameter))
 	pp_cxx_tree_identifier (pp, DECL_NAME (parameter));
@@ -2463,6 +2463,7 @@  cxx_pretty_printer::declaration (tree t)
       }
   else switch (TREE_CODE (t))
     {
+    case FIELD_DECL:
     case VAR_DECL:
     case TYPE_DECL:
       pp_cxx_simple_declaration (this, t);
diff --git a/gcc/dumpfile.cc b/gcc/dumpfile.cc
index 074da7df2169..5977e938b636 100644
--- a/gcc/dumpfile.cc
+++ b/gcc/dumpfile.cc
@@ -108,7 +108,7 @@  static struct dump_file_info dump_files[TDI_end] =
   DUMP_FILE_INFO (".lto-stream-out", "ipa-lto-stream-out", DK_ipa, 0),
   DUMP_FILE_INFO (".profile-report", "profile-report", DK_ipa, 0),
 #define FIRST_AUTO_NUMBERED_DUMP 1
-#define FIRST_ME_AUTO_NUMBERED_DUMP 5
+#define FIRST_ME_AUTO_NUMBERED_DUMP 6
 
   DUMP_FILE_INFO (NULL, "lang-all", DK_lang, 0),
   DUMP_FILE_INFO (NULL, "tree-all", DK_tree, 0),