This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[patch] Limit DW_AT_comp_dir workaround only for gcc<=4.2


Hi,

there was commit
	[commit] Handle files without DW_AT_comp_dir
	Message-ID: <20070604123615.GA22533@caradoc.them.org>
	http://sourceware.org/ml/gdb-patches/2007-06/msg00031.html
with further discusssion
	Message-ID: <20120406123641.GA18063@host2.jankratochvil.net>
	http://sourceware.org/ml/gdb-patches/2012-04/msg00105.html

That commit started to guess DW_AT_comp_dir if it was missing, because with
some GCC versions .debug_line could contain a relative directory.  But
DW_AT_comp_dir is always only a best guess (dirname of CU's DW_AT_name), it
may be commonly wrong as shown in:
	Subject: Re: [commit] Handle files without DW_AT_comp_dir
	Message-ID: <20120409154750.GA15639@host2.jankratochvil.net>
	http://sourceware.org/ml/gdb-patches/2012-04/msg00148.html

This guessed DW_AT_comp_dir (IMO) caused later confusion during implementation
of:
	[patch] GDB 7.2: new feature for "backtrace" that cuts path to file (remain filename)
	Message-ID: <BANLkTinD+9_Mkug8o2VhZ03L6XSriL_RKQ@mail.gmail.com>
	http://sourceware.org/ml/gdb-patches/2011-06/msg00385.html
	(with many replies on following months)

The GCC bug was fixed along a different feature, released first as gcc-4.3.0:
	Subject: Debug info path remapping
	Message-ID: <Pine.LNX.4.64.0707050046160.26969@digraph.polyomino.org.uk>
	http://gcc.gnu.org/ml/gcc-patches/2007-07/msg00404.html
	GCC GIT commit 5f1f2de5fe3f87b056e802102fcb975979845eff

I do not know since which GCC version had the missing DW_AT_comp_dir bug.
FSF GCC 3.3.5                       PASS - .debug_line directory is absolute
FSF GCC 4.0.4                       unknown, it fails to build for me
FSF GCC 4.2.5 20090330 (prerelease) FAIL - DW_AT_comp_dir missing
FSF GCC 4.3.6                       PASS - DW_AT_comp_dir present

So I have kept the workaround there for anyhing < 4.3.0, it is at least no GDB
change for those GCC versions.

This is more a pre-requisite for the later new post of:
	[patch] GDB 7.2: new feature for "backtrace" that cuts path to file (remain filename)

No regressions on {x86_64,x86_64-m32,i686}-fedora18-linux-gnu.


Thanks,
Jan


gdb/
2012-11-30  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2read.c (struct dwarf2_cu): New field producer_is_gcc_lt_4_3.
	Update the comment for checked_producer.
	(check_producer): New forward declaration.
	(producer_is_gcc_lt_4_3): New function.
	(find_file_and_directory): Simulate *COMP_DIR only for gcc < 4.3.
	(check_producer): Initialize also PRODUCER_IS_GCC_LT_4_3.

gdb/testsuite/
2012-11-30  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.dwarf2/dw2-compdir-oldgcc.S: New file.
	* gdb.dwarf2/dw2-compdir-oldgcc.exp: New file.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index f4bd7a9..c0c0755 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -492,12 +492,13 @@ struct dwarf2_cu
      unoptimized code.  For a future better test see GCC PR other/32998.  */
   unsigned int has_loclist : 1;
 
-  /* These cache the results for producer_is_gxx_lt_4_6 and producer_is_icc.
-     CHECKED_PRODUCER is set if both PRODUCER_IS_GXX_LT_4_6 and PRODUCER_IS_ICC
-     are valid.  This information is cached because profiling CU expansion
-     showed excessive time spent in producer_is_gxx_lt_4_6.  */
+  /* These cache the results for producer_is_* fields.  CHECKED_PRODUCER is set
+     if all the producer_is_* fields are valid.  This information is cached
+     because profiling CU expansion showed excessive time spent in
+     producer_is_gxx_lt_4_6.  */
   unsigned int checked_producer : 1;
   unsigned int producer_is_gxx_lt_4_6 : 1;
+  unsigned int producer_is_gcc_lt_4_3 : 1;
   unsigned int producer_is_icc : 1;
 };
 
@@ -1710,6 +1711,8 @@ static void free_dwo_file_cleanup (void *);
 
 static void process_cu_includes (void);
 
+static void check_producer (struct dwarf2_cu *cu);
+
 #if WORDS_BIGENDIAN
 
 /* Convert VALUE between big- and little-endian.  */
@@ -7803,6 +7806,19 @@ free_cu_line_header (void *arg)
   cu->line_header = NULL;
 }
 
+/* Check for possibly missing DW_AT_comp_dir with relative .debug_line
+   directory paths.  GCC SVN r127613 (new option -fdebug-prefix-map) fixed
+   this, it was first present in GCC release 4.3.0.  */
+
+static int
+producer_is_gcc_lt_4_3 (struct dwarf2_cu *cu)
+{
+  if (!cu->checked_producer)
+    check_producer (cu);
+
+  return cu->producer_is_gcc_lt_4_3;
+}
+
 static void
 find_file_and_directory (struct die_info *die, struct dwarf2_cu *cu,
 			 char **name, char **comp_dir)
@@ -7823,7 +7839,8 @@ find_file_and_directory (struct die_info *die, struct dwarf2_cu *cu,
   attr = dwarf2_attr (die, DW_AT_comp_dir, cu);
   if (attr)
     *comp_dir = DW_STRING (attr);
-  else if (*name != NULL && IS_ABSOLUTE_PATH (*name))
+  else if (producer_is_gcc_lt_4_3 (cu) && *name != NULL
+	   && IS_ABSOLUTE_PATH (*name))
     {
       *comp_dir = ldirname (*name);
       if (*comp_dir != NULL)
@@ -10357,7 +10374,10 @@ check_producer (struct dwarf2_cu *cu)
 	  /* Not recognized as GCC.  */
 	}
       else
-	cu->producer_is_gxx_lt_4_6 = major < 4 || (major == 4 && minor < 6);
+	{
+	  cu->producer_is_gxx_lt_4_6 = major < 4 || (major == 4 && minor < 6);
+	  cu->producer_is_gcc_lt_4_3 = major < 4 || (major == 4 && minor < 3);
+	}
     }
   else if (strncmp (cu->producer, "Intel(R) C", strlen ("Intel(R) C")) == 0)
     cu->producer_is_icc = 1;
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.S b/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.S
new file mode 100644
index 0000000..8c1ed04
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.S
@@ -0,0 +1,230 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012 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/>.  */
+
+	.text
+main:	.globl main
+
+gcc42:	.globl gcc42
+	.int 0
+	.type gcc42, %function
+	.size gcc42, . - gcc42
+.Lgcc42_procend:
+
+gcc43:	.globl gcc43
+	.int 0
+	.type gcc43, %function
+	.size gcc43, . - gcc43
+.Lgcc43_procend:
+
+/* 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 */
+
+	.uleb128 1				/* Abbrev: DW_TAG_compile_unit */
+	.4byte	.Lgcc42_begin			/* DW_AT_stmt_list */
+	.4byte	gcc42				/* DW_AT_low_pc */
+	.4byte	.Lgcc42_procend			/* DW_AT_high_pc */
+	.ascii	"/dir/d/dw2-compdir-oldgcc42.S\0"	/* DW_AT_name */
+	.ascii	"GNU C 4.2.0\0"			/* DW_AT_producer */
+	.byte	1				/* DW_AT_language (C) */
+
+	.uleb128	2			/* Abbrev: DW_TAG_subprogram */
+	.byte		1			/* DW_AT_external */
+	.byte		1			/* DW_AT_decl_file */
+	.byte		1			/* DW_AT_decl_line */
+	.ascii		"gcc42\0"		/* DW_AT_name */
+	.4byte		gcc42			/* DW_AT_low_pc */
+	.4byte		.Lgcc42_procend		/* DW_AT_high_pc */
+
+	.byte		0			/* End of children of CU */
+.Lcu1_end:
+
+.Lcu2_begin:
+	/* CU header */
+	.4byte	.Lcu2_end - .Lcu2_start	/* Length of Compilation Unit */
+.Lcu2_start:
+	.2byte	2				/* DWARF Version */
+	.4byte	.Labbrev1_begin			/* Offset into abbrev section */
+	.byte	4				/* Pointer size */
+
+	.uleb128 1				/* Abbrev: DW_TAG_compile_unit */
+	.4byte	.Lgcc43_begin			/* DW_AT_stmt_list */
+	.4byte	gcc43				/* DW_AT_low_pc */
+	.4byte	.Lgcc43_procend			/* DW_AT_high_pc */
+	.ascii	"/dir/d/dw2-compdir-oldgcc43.S\0"	/* DW_AT_name */
+	.ascii	"GNU C 4.3.0\0"			/* DW_AT_producer */
+	.byte	1				/* DW_AT_language (C) */
+
+	.uleb128	2			/* Abbrev: DW_TAG_subprogram */
+	.byte		1			/* DW_AT_external */
+	.byte		1			/* DW_AT_decl_file */
+	.byte		1			/* DW_AT_decl_line */
+	.ascii		"gcc43\0"		/* DW_AT_name */
+	.4byte		gcc43			/* DW_AT_low_pc */
+	.4byte		.Lgcc43_procend		/* DW_AT_high_pc */
+
+	.byte		0			/* End of children of CU */
+.Lcu2_end:
+
+/* Abbrev table */
+	.section .debug_abbrev
+.Labbrev1_begin:
+	.uleb128	1			/* Abbrev code */
+	.uleb128	0x11			/* DW_TAG_compile_unit */
+	.byte		1			/* has_children */
+	.uleb128	0x10			/* DW_AT_stmt_list */
+	.uleb128	0x6			/* DW_FORM_data4 */
+	.uleb128	0x11			/* DW_AT_low_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.uleb128	0x12			/* DW_AT_high_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.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	0x2e			/* DW_TAG_subprogram */
+	.byte		0			/* has_children */
+	.uleb128	0x3f			/* DW_AT_external */
+	.uleb128	0xc			/* DW_FORM_flag */
+	.uleb128	0x3a			/* DW_AT_decl_file */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.uleb128	0x3b			/* DW_AT_decl_line */
+	.uleb128	0xb			/* DW_FORM_data1 */
+	.uleb128	0x3			/* DW_AT_name */
+	.uleb128	0x8			/* DW_FORM_string */
+	.uleb128	0x11			/* DW_AT_low_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.uleb128	0x12			/* DW_AT_high_pc */
+	.uleb128	0x1			/* DW_FORM_addr */
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+	.byte		0x0			/* Terminator */
+	.byte		0x0			/* Terminator */
+
+/* Line table */
+	.section .debug_line
+.Lgcc42_begin:
+	.4byte		.Lgcc42_end - .Lgcc42_start	/* Initial length */
+.Lgcc42_start:
+	.2byte		2			/* Version */
+	.4byte		.Lgcc42_lines - .Lgcc42_hdr	/* header_length */
+.Lgcc42_hdr:
+	.byte		1			/* Minimum insn length */
+	.byte		1			/* default_is_stmt */
+	.byte		1			/* line_base */
+ 	.byte		1			/* line_range */
+	.byte		4			/* opcode_base */
+
+	/* Standard lengths */
+	.byte		0
+	.byte		1
+	.byte		1
+
+	/* Include directories */
+	.byte		0
+
+	/* File names */
+	.ascii		"dw2-compdir-oldgcc42.S\0"
+	.uleb128	0	/* directory */
+	.uleb128	0
+	.uleb128	0
+
+	.byte		0
+
+.Lgcc42_lines:
+	.byte		0	/* DW_LNE_set_address */
+	.uleb128	5
+	.byte		2
+	.4byte		gcc42
+
+	.byte		3	/* DW_LNS_advance_line */
+	.sleb128	41	/* ... to 42 */
+
+	.byte		1	/* DW_LNS_copy */
+
+	.byte		0	/* DW_LNE_set_address */
+	.uleb128	5
+	.byte		2
+	.4byte		.Lgcc42_procend
+
+	.byte		0	/* DW_LNE_end_of_sequence */
+	.uleb128	1
+	.byte		1
+.Lgcc42_end:
+
+.Lgcc43_begin:
+	.4byte		.Lgcc43_end - .Lgcc43_start	/* Initial length */
+.Lgcc43_start:
+	.2byte		2			/* Version */
+	.4byte		.Lgcc43_lines - .Lgcc43_hdr	/* header_length */
+.Lgcc43_hdr:
+	.byte		1			/* Minimum insn length */
+	.byte		1			/* default_is_stmt */
+	.byte		1			/* line_base */
+ 	.byte		1			/* line_range */
+	.byte		4			/* opcode_base */
+
+	/* Standard lengths */
+	.byte		0
+	.byte		1
+	.byte		1
+
+	/* Include directories */
+	.byte		0
+
+	/* File names */
+	.ascii		"dw2-compdir-oldgcc43.S\0"
+	.uleb128	0	/* directory */
+	.uleb128	0
+	.uleb128	0
+
+	.byte		0
+
+.Lgcc43_lines:
+	.byte		0	/* DW_LNE_set_address */
+	.uleb128	5
+	.byte		2
+	.4byte		gcc43
+
+	.byte		3	/* DW_LNS_advance_line */
+	.sleb128	42	/* ... to 43 */
+
+	.byte		1	/* DW_LNS_copy */
+
+	.byte		0	/* DW_LNE_set_address */
+	.uleb128	5
+	.byte		2
+	.4byte		.Lgcc43_procend
+
+	.byte		0	/* DW_LNE_end_of_sequence */
+	.uleb128	1
+	.byte		1
+.Lgcc43_end:
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.exp b/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.exp
new file mode 100644
index 0000000..c3c0209
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-compdir-oldgcc.exp
@@ -0,0 +1,42 @@
+# Copyright 2012 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
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0  
+}
+
+standard_testfile .S
+if {[prepare_for_testing $testfile.exp $testfile $srcfile]} {
+    return -1
+}
+
+# Here should be GDB-computed "Compilation directory is".
+gdb_test "list gcc42" ".*"
+gdb_test "info source" "\r\nCurrent source file is dw2-compdir-oldgcc42.S\r\nCompilation directory is /dir/d\r\n.*" \
+	 "info source gcc42"
+
+# Here should not be GDB-computed "Compilation directory is".
+gdb_test "list gcc43" ".*"
+set test "info source gcc43"
+gdb_test_multiple "info source" $test {
+    -re "\r\nCompilation directory is .*\r\n$gdb_prompt $" {
+	fail $test
+    }
+    -re "\r\nCurrent source file is dw2-compdir-oldgcc43.S\r\n.*\r\n$gdb_prompt $" {
+	pass $test
+    }
+}


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]