gdb/gdb-gcc46-typedef.patch

http://sourceware.org/ml/gdb-patches/2011-04/msg00154.html
Subject: [patch] Workaround buggy GCC PR 47510 produced code

Hi,

GCC PR debug/47510 is already fixed and GDB has the proper support for it:
	RFC: update for GCC PR 47510
	http://sourceware.org/ml/gdb-patches/2011-03/msg00916.html

Still FSF GDB HEAD will crash on a binary produced by older/buggy GCC:
	Reading symbols from .../gcc46.o...dwarf2read.c:9329: internal-error: could not find partial DIE 0x9a in cache [from module .../gcc46.o]

Which may not give much clue to the user.

The proposed patch could make false warnings if any code out there has
DW_TAG_typedef with children, it does not check for specific GCC versions.
Still such DWARF is invalid, although in such case complaint() would be more
appropriate than warning().  Does it make sense to differentiate it?

No regressions on {x86_64,x86_64-m32,i686}-fedora15-linux-gnu.


Thanks,
Jan


gdb/
2011-04-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2read.c (struct dwarf2_per_objfile): New field
	typedef_children_warning_printed.
	(load_partial_dies): Read in any children of DW_TAG_typedef with
	a warning in such case.

gdb/testsuite/
2011-04-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.dwarf2/dw2-typedef-children.S: New file.
	* gdb.dwarf2/dw2-typedef-children.exp: New file.

--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -209,6 +209,9 @@ struct dwarf2_per_objfile
      or we are faking it for OBJF_READNOW's sake.  */
   unsigned char using_index;
 
+  /* Print the GCC PR debug/47510 warning only once per objfile.  */
+  unsigned typedef_children_warning_printed : 1;
+
   /* The mapped index, or NULL if .gdb_index is missing or not being used.  */
   struct mapped_index *index_table;
 
@@ -8951,7 +8954,7 @@ load_partial_dies (bfd *abfd, gdb_byte *buffer, gdb_byte *info_ptr,
       if (parent_die == NULL
 	  && part_die->has_specification == 0
 	  && part_die->is_declaration == 0
-	  && (part_die->tag == DW_TAG_typedef
+	  && ((part_die->tag == DW_TAG_typedef && !part_die->has_children)
 	      || part_die->tag == DW_TAG_base_type
 	      || part_die->tag == DW_TAG_subrange_type))
 	{
@@ -8964,6 +8967,20 @@ load_partial_dies (bfd *abfd, gdb_byte *buffer, gdb_byte *info_ptr,
 	  continue;
 	}
 
+      /* The exception for DW_TAG_typedef with has_children above is
+	 a workaround of GCC PR debug/47510.  GDB crashed on broken GCC output
+	 as it skipped children of DW_TAG_typedef by the shortcut above and
+	 then it could not find the child DIEs referenced later.  */
+
+      if (!dwarf2_per_objfile->typedef_children_warning_printed
+	  && part_die->tag == DW_TAG_typedef && part_die->has_children)
+	{
+	  warning (_("DW_TAG_typedef has childen - GCC PR debug/47510 bug "
+		     "- DIE at 0x%x [in module %s]"),
+		   part_die->offset, cu->objfile->name);
+	  dwarf2_per_objfile->typedef_children_warning_printed = 1;
+	}
+
       /* If we're at the second level, and we're an enumerator, and
 	 our parent has no specification (meaning possibly lives in a
 	 namespace elsewhere), then we can add the partial symbol now
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-typedef-children.S
@@ -0,0 +1,92 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011 Free Software Foundation, Inc.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Debug information */
+
+	.section .debug_info
+.Lcu1_begin:
+	/* CU header */
+	.4byte	.Lcu1_end - .Lcu1_start		/* Length of Compilation Unit */
+.Lcu1_start:
+	.2byte	2				/* DWARF Version */
+	.4byte	.Labbrev1_begin			/* Offset into abbrev section */
+	.byte	4				/* Pointer size */
+
+	/* CU die */
+	.uleb128 1				/* Abbrev: DW_TAG_compile_unit */
+	.ascii	"file1.txt\0"			/* DW_AT_name */
+	.ascii	"GNU C 3.3.3\0"			/* DW_AT_producer */
+	.byte	1				/* DW_AT_language (C) */
+
+.Ltype_int:
+	.uleb128	2			/* Abbrev: DW_TAG_base_type */
+	.ascii		"int\0"			/* DW_AT_name */
+	.byte		4			/* DW_AT_byte_size */
+	.byte		5			/* DW_AT_encoding */
+
+	.uleb128	0x3			/* (DIE (0x38) DW_TAG_typedef) */
+	.ascii		"new\0"			/* DW_AT_name */
+	.long		.Ltype_int - .Lcu1_begin	/* DW_AT_type */
+
+	.uleb128	2			/* Abbrev: DW_TAG_base_type */
+	.ascii		"int\0"			/* DW_AT_name */
+	.byte		4			/* DW_AT_byte_size */
+	.byte		5			/* DW_AT_encoding */
+
+	.uleb128	0			/* End of DW_TAG_typedef */
+	.uleb128	0			/* End of DW_TAG_compile_unit */
+.Lcu1_end:
+
+/* Abbrev table */
+	.section .debug_abbrev
+.Labbrev1_begin:
+	.uleb128	1			/* Abbrev code */
+	.uleb128	0x11			/* DW_TAG_compile_unit */
+	.byte		1			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x25			/* DW_AT_producer */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x13			/* DW_AT_language */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.uleb128	2			/* Abbrev code */
+	.uleb128	0x24			/* DW_TAG_base_type */
+	.byte		0			/* has_children */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0xb			/* DW_AT_byte_size */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.uleb128	0x3e			/* DW_AT_encoding */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.uleb128	0x3			/* (abbrev code) */
+	.uleb128	0x16			/* (TAG: DW_TAG_typedef) */
+	.byte		0x1			/* DW_children_yes */
+	.uleb128	0x3			/* (DW_AT_name) */
+	.uleb128	0x8			/* (DW_FORM_string) */
+	.uleb128	0x49			/* (DW_AT_type) */
+	.uleb128	0x13			/* (DW_FORM_ref4) */
+	.byte		0x0
+	.byte		0x0
+
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-typedef-children.exp
@@ -0,0 +1,37 @@
+# Copyright 2011 Free Software Foundation, Inc.
+
+# This program 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 of the License, or
+# (at your option) any later version.
+#
+# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+load_lib dwarf.exp
+
+# Note: Inspired from dw2-basic.exp.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+set testfile "dw2-typedef-children"
+set srcfile ${testfile}.S
+set binfile ${objdir}/${subdir}/${testfile}.x
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" object {nodebug}] != "" } {
+    return -1
+}
+
+gdb_exit
+gdb_start
+
+gdb_test "file $binfile" \
+	 "warning: DW_TAG_typedef has childen - GCC PR debug/47510 bug - DIE at .*" \
+	 "warning message"