[PATCH v2 1/4] Support for CodeView debugging format

This patch and the following add initial support for Microsoft's
CodeView debugging format, as used by MSVC, to mingw targets.

Note that you will need a recent version of binutils for this to be
useful. The best way to view the output is to run Microsoft's
cvdump.exe, found in their microsoft-pdb repo on GitHub, against the
object files.

gcc/

	* Makefile.in (OBJS): Add dwarf2codeview.o.
	(GTFILES): Add dwarf2codeview.cc
	* config/i386/cygming.h (CODEVIEW_DEBUGGING_INFO): Define.
	* dwarf2codeview.cc: New file.
	* dwarf2codeview.h: New file.
	* dwarf2out.cc: Include dwarf2codeview.h.
	(dwarf2out_finish): Call codeview_debug_finish as needed.
	* flag-types.h (DINFO_TYPE_CODEVIEW): Add enum member.
	(CODEVIEW_DEBUG): Define.
	* flags.h (codeview_debuginfo_p): Proottype.
	* opts.cc (debug_type_names): Add codeview.
	(debug_type_masks): Add CODEVIEW_DEBUG.
	(df_set_names): Add codeview.
	(codeview_debuginfo_p): New function.
	(dwarf_based_debuginfo_p): Add CODEVIEW clause.
	(set_debug_level): Handle CODEVIEW_DEBUG.
	* toplev.cc (process_options): Handle codeview.

gcc/testsuite
	* gcc.dg/debug/codeview/codeview-1.c: New test.
	* gcc.dg/debug/codeview/codeview.exp: New testsuite driver.

1 files changed, 54 insertions, 0 deletions

diff --git a/gcc/dwarf2codeview.cc b/gcc/dwarf2codeview.cc
new file mode 100644
index 0000000..f08f5d5
--- /dev/null
+++ b/gcc/dwarf2codeview.cc
@@ -0,0 +1,54 @@
+/* Generate CodeView debugging info from the GCC DWARF.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+/* See gas/codeview.h in binutils for more about the constants and structs
+   listed below.  References to Microsoft files refer to Microsoft's PDB
+   repository: https://github.com/microsoft/microsoft-pdb.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "target.h"
+#include "output.h"
+#include "errors.h"
+#include "md5.h"
+#include "function.h"
+#include "version.h"
+#include "tree.h"
+#include "langhooks.h"
+#include "dwarf2out.h"
+#include "dwarf2codeview.h"
+
+#ifdef CODEVIEW_DEBUGGING_INFO
+
+#define CV_SIGNATURE_C13	4
+
+/* Finish CodeView debug info emission.  */
+
+void
+codeview_debug_finish (void)
+{
+  targetm.asm_out.named_section (".debug$S", SECTION_DEBUG, NULL);
+
+  fputs (integer_asm_op (4, false), asm_out_file);
+  fprint_whex (asm_out_file, CV_SIGNATURE_C13);
+  putc ('\n', asm_out_file);
+}
+
+#endif