[dwarf] Anonymous nested function causes SEGV during psymbol read

According to the DWARF3 standard, a function always has a name attribute
(Section 3.3 - Subroutine and Entry Point Entries).  The only exception
is when a DW_AT_abstract_origin attribute is provided, in which case
the name may be inherited from the referenced DIE.

The problem occured because our compiler generated a subprogram DIE
for a nested function where the name attribute was missing (and no
abstract-origin either).  Our code in add_partial_symbol is not
prepared to deal with the situation, and happily just tries  to compute
the length of the (NULL) function name.

This normally cannot happen, because there is already a guard in
scan_partial_symbols, where we (silently!) ignore anonymous dies,
including anonymous subprograms. Unfortunately, there is a flaw that
affects Ada and other languages that allow nested subprograms. For
nested subprograms, we do not go through scan_partial_symbols and
thus we are missing the name check.

This patch adds the name check in the nested subprogram case. It also
adds a complaint which is emitted during the psymtab->symtab conversion
phase.

gdb/ChangeLog:

        * dwarf2read.c (add_partial_subprogram): Make sure the subprogram
        DIE has a name before creating the associated partial symbol.
        (read_func_scope): Emit a complaint if the subprogram does not
        have a name or when we can't extract the subprogram PC bounds.

gdb/testsuite/ChangeLog:

        * gdb.dwarf2/dw2-anonymous-func.S: New file.
        * gdb.dwarf2/dw2-anonymous-func.exp: New testcase.

Tested on x86_64-linux, no regression.  Note that the testcase also
verifies that the psymtab->symtab conversion does not crash (this is
the purpose of the "list file1.txt:1" test.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 746af29..2cf42aa 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -3,6 +3,13 @@
        * infcmd.c (finish_command_continuation): Wrap print_return_value
        in TRY_CATCH.
 
+2010-03-18  Joel Brobecker  <brobecker@adacore.com>
+
+       * dwarf2read.c (add_partial_subprogram): Make sure the subprogram
+       DIE has a name before creating the associated partial symbol.
+       (read_func_scope): Emit a complaint if the subprogram does not
+       have a name or when we can't extract the subprogram PC bounds.
+
 2010-03-18  Ulrich Weigand  <uweigand@de.ibm.com>
 
        * mi/mi-main.c (mi_cmd_list_thread_groups): Use get_current_arch

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 3789d09..92cda0e 100644 (file)
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2583,7 +2583,11 @@ add_partial_subprogram (struct partial_die_info *pdi,
                                 cu->per_cu->psymtab);
            }
           if (!pdi->is_declaration)
-            add_partial_symbol (pdi, cu);
+           /* Ignore subprogram DIEs that do not have a name, they are
+              illegal.  Do not emit a complaint at this point, we will
+              do so when we convert this psymtab into a symtab.  */
+           if (pdi->name)
+             add_partial_symbol (pdi, cu);
         }
     }
   
@@ -3867,10 +3871,23 @@ read_func_scope (struct die_info *die, struct dwarf2_cu *cu)
 
   name = dwarf2_name (die, cu);
 
-  /* Ignore functions with missing or empty names and functions with
-     missing or invalid low and high pc attributes.  */
-  if (name == NULL || !dwarf2_get_pc_bounds (die, &lowpc, &highpc, cu, NULL))
-    return;
+  /* Ignore functions with missing or empty names.  These are actually
+     illegal according to the DWARF standard.  */
+  if (name == NULL)
+    {
+      complaint (&symfile_complaints,
+                 _("missing name for subprogram DIE at %d"), die->offset);
+      return;
+    }
+
+  /* Ignore functions with missing or invalid low and high pc attributes.  */
+  if (!dwarf2_get_pc_bounds (die, &lowpc, &highpc, cu, NULL))
+    {
+      complaint (&symfile_complaints,
+                 _("cannot get low and high bounds for subprogram DIE at %d"),
+                 die->offset);
+      return;
+    }
 
   lowpc += baseaddr;
   highpc += baseaddr;

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index efa22d9..8c60bdc 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-03-18  Joel Brobecker  <brobecker@adacore.com>
+
+       * gdb.dwarf2/dw2-anonymous-func.S: New file.
+       * gdb.dwarf2/dw2-anonymous-func.exp: New testcase.
+
 2010-03-18  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
 
        * gdb.mi/gdb680.exp: Revert 2009-06-17 change.

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.S b/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.S
new file mode 100644 (file)
index 0000000..84552bf
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.S
@@ -0,0 +1,248 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2004, 2007, 2008, 2009, 2010 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/>.  */
+
+/* Test a minimal file containing DWARF-2 information.  This test also
+   serves as a skeleton for other DWARF-2 tests.  Most other tests will
+   not be this extensively itemized and commented...  */
+
+/* Dummy function to provide debug information for.  */
+
+       .text
+.Lbegin_text1:
+       .globl func_cu1
+       .type func_cu1, %function
+func_cu1:
+.Lbegin_func_cu1:
+       .int 0
+.Lend_func_cu1:
+       .size func_cu1, .-func_cu1
+       .globl func_cu2
+       .type func_cu2, %function
+func_cu2:
+.Lbegin_func_cu2:
+       .int 0
+.Lend_func_cu2:
+       .size func_cu2, .-func_cu2
+.Lend_text1:
+
+/* 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 */
+       .4byte  .Lline1_begin                   /* DW_AT_stmt_list */
+       .4byte  .Lend_text1                     /* DW_AT_high_pc */
+       .4byte  .Lbegin_text1                   /* DW_AT_low_pc */
+       .ascii  "file1.txt\0"                   /* DW_AT_name */
+       .ascii  "GNU C 3.3.3\0"                 /* DW_AT_producer */
+       .byte   0x0d                            /* DW_AT_language (Ada95) */
+
+       /* func_cu1 */
+       .uleb128        2                       /* Abbrev: DW_TAG_subprogram */
+       .byte           1                       /* DW_AT_external */
+       .byte           1                       /* DW_AT_decl_file */
+       .byte           2                       /* DW_AT_decl_line */
+       .ascii          "func_cu1\0"            /* DW_AT_name */
+       .4byte          .Ltype_int-.Lcu1_begin  /* DW_AT_type */
+       .4byte          .Lbegin_func_cu1        /* DW_AT_low_pc */
+       .4byte          .Lend_func_cu1          /* DW_AT_high_pc */
+       .byte           1                       /* DW_AT_frame_base: length */
+       .byte           0x55                    /* DW_AT_frame_base: DW_OP_reg5 */
+       /* Nested function missing a name attribute.  */
+       .uleb128        4                       /* Abbrev: DW_TAG_subprogram */
+       .byte           1                       /* DW_AT_external */
+       .byte           1                       /* DW_AT_decl_file */
+       .byte           2                       /* DW_AT_decl_line */
+       .4byte          .Ltype_int-.Lcu1_begin  /* DW_AT_type */
+       .4byte          .Lbegin_func_cu2        /* DW_AT_low_pc */
+       .4byte          .Lend_func_cu2          /* DW_AT_high_pc */
+       .byte           1                       /* DW_AT_frame_base: length */
+       .byte           0x55                    /* DW_AT_frame_base: DW_OP_reg5 */
+       .byte           0x0                     /* End of children of func_cu1 */
+
+       /* Non-nested function missing a name attribute.  */
+       .uleb128        4                       /* Abbrev: DW_TAG_subprogram */
+       .byte           1                       /* DW_AT_external */
+       .byte           1                       /* DW_AT_decl_file */
+       .byte           2                       /* DW_AT_decl_line */
+       .4byte          .Ltype_int-.Lcu1_begin  /* DW_AT_type */
+       .4byte          .Lbegin_func_cu2        /* DW_AT_low_pc */
+       .4byte          .Lend_func_cu2          /* DW_AT_high_pc */
+       .byte           1                       /* DW_AT_frame_base: length */
+       .byte           0x55                    /* DW_AT_frame_base: DW_OP_reg5 */
+
+.Ltype_int:
+       .uleb128        3                       /* Abbrev: DW_TAG_base_type */
+       .ascii          "int\0"                 /* DW_AT_name */
+       .byte           4                       /* DW_AT_byte_size */
+       .byte           5                       /* DW_AT_encoding */
+
+       .byte           0                       /* End of children of CU */
+
+.Lcu1_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        0x12                    /* DW_AT_high_pc */
+       .uleb128        0x1                     /* DW_FORM_addr */
+       .uleb128        0x11                    /* DW_AT_low_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           1                       /* 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        0x49                    /* DW_AT_type */
+       .uleb128        0x13                    /* DW_FORM_ref4 */
+       .uleb128        0x11                    /* DW_AT_low_pc */
+       .uleb128        0x1                     /* DW_FORM_addr */
+       .uleb128        0x12                    /* DW_AT_high_pc */
+       .uleb128        0x1                     /* DW_FORM_addr */
+       .uleb128        0x40                    /* DW_AT_frame_base */
+       .uleb128        0xa                     /* DW_FORM_block1 */
+       .byte           0x0                     /* Terminator */
+       .byte           0x0                     /* Terminator */
+
+       .uleb128        3                       /* 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        4                       /* 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        0x49                    /* DW_AT_type */
+       .uleb128        0x13                    /* DW_FORM_ref4 */
+       .uleb128        0x11                    /* DW_AT_low_pc */
+       .uleb128        0x1                     /* DW_FORM_addr */
+       .uleb128        0x12                    /* DW_AT_high_pc */
+       .uleb128        0x1                     /* DW_FORM_addr */
+       .uleb128        0x40                    /* DW_AT_frame_base */
+       .uleb128        0xa                     /* DW_FORM_block1 */
+       .byte           0x0                     /* Terminator */
+       .byte           0x0                     /* Terminator */
+
+       .byte           0x0                     /* Terminator */
+       .byte           0x0                     /* Terminator */
+
+/* Line table */
+       .section .debug_line
+.Lline1_begin:
+       .4byte          .Lline1_end - .Lline1_start     /* Initial length */
+.Lline1_start:
+       .2byte          2                       /* Version */
+       .4byte          .Lline1_lines - .Lline1_hdr     /* header_length */
+.Lline1_hdr:
+       .byte           1                       /* Minimum insn length */
+       .byte           1                       /* default_is_stmt */
+       .byte           1                       /* line_base */
+       .byte           1                       /* line_range */
+       .byte           0x10                    /* opcode_base */
+
+       /* Standard lengths */
+       .byte           0
+       .byte           1
+       .byte           1
+       .byte           1
+       .byte           1
+       .byte           0
+       .byte           0
+       .byte           0
+       .byte           1
+       .byte           0
+       .byte           0
+       .byte           1
+       .byte           0
+       .byte           0
+       .byte           0
+
+       /* Include directories */
+       .byte           0
+
+       /* File names */
+       .ascii          "file1.txt\0"
+       .uleb128        0
+       .uleb128        0
+       .uleb128        0
+
+       .byte           0
+
+.Lline1_lines:
+       .byte           0       /* DW_LNE_set_address */
+       .uleb128        5
+       .byte           2
+       .4byte          .Lbegin_func_cu1
+
+       .byte           3       /* DW_LNS_advance_line */
+       .sleb128        3       /* ... to 4 */
+
+       .byte           1       /* DW_LNS_copy */
+
+       .byte           1       /* DW_LNS_copy (second time as an end-of-prologue marker) */
+
+       .byte           0       /* DW_LNE_set_address */
+       .uleb128        5
+       .byte           2
+       .4byte          .Lend_func_cu1
+
+       .byte           0       /* DW_LNE_end_of_sequence */
+       .uleb128        1
+       .byte           1
+
+.Lline1_end:

diff --git a/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.exp b/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.exp
new file mode 100644 (file)
index 0000000..10662eb
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-anonymous-func.exp
@@ -0,0 +1,53 @@
+# Copyright 2004, 2005, 2007, 2008, 2009, 2010 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/>.
+
+# Minimal DWARF-2 unit test
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+    && ![istarget *-*-gnu*]
+    && ![istarget *-*-elf*]
+    && ![istarget *-*-openbsd*]
+    && ![istarget arm-*-eabi*]
+    && ![istarget powerpc-*-eabi*]} {
+    return 0
+}
+
+set testfile "dw2-anonymous-func"
+set dwarf_srcfile "file1.txt"
+set srcfile ${testfile}.S
+set binfile ${objdir}/${subdir}/${testfile}.x
+
+if  { [gdb_compile "${srcdir}/${subdir}/main.c" "main.o" object {debug}] != "" } {
+    return -1
+}
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${testfile}.o" object {nodebug}] != "" } {
+    return -1
+}
+
+if  { [gdb_compile "${testfile}.o main.o" "${binfile}" executable {debug}] != "" } {
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Force the debugger to create the file1.txt symtab, to make sure that
+# the debugger does not crash doing so.
+gdb_test "list file1.txt:1" "File 1 Line 1.*File 1 Line 8" "list file1.txt"