[patch] Re: Advice on fixing gdb/12528

[Paul Pluzhnikov <ppluzhnikov@google.com>]

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On Fri, Mar 11, 2011 at 9:14 AM, Tom Tromey <tromey@redhat.com> wrote:

> Can you check the has_section_at_zero flag on dwarf2_per_objfile?

Thanks!

Attached patch fixes the problem and adds a test case.
Tested on Linux/x86_64, no regressions.

-- 
Paul Pluzhnikov

ChangeLog:

2011-03-14  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/12528
	* dwarf2read.c (noop_record_line): New function.
	(dwarf_decode_lines): Ignore line tables for GCd functions.

testsuite/ChangeLog:

2011-03-14  Paul Pluzhnikov  <ppluzhnikov@google.com>

	PR gdb/12528
	* gdb.cp/pr12528.exp: New test.
	* gdb.cp/pr12528.cc: New file.

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Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.508
diff -u -p -p -u -r1.508 dwarf2read.c
--- dwarf2read.c	9 Mar 2011 07:07:55 -0000	1.508
+++ dwarf2read.c	14 Mar 2011 20:52:11 -0000
@@ -10341,6 +10341,14 @@ psymtab_include_file_name (const struct 
   return include_name;
 }
 
+/* Ignore this record_line request.  */
+
+static void
+noop_record_line (struct subfile *subfile, int line, CORE_ADDR pc)
+{
+  return;
+}
+
 /* Decode the Line Number Program (LNP) for the given line_header
    structure and CU.  The actual information extracted and the type
    of structures created from the LNP depends on the value of PST.
@@ -10376,6 +10384,8 @@ dwarf_decode_lines (struct line_header *
   struct gdbarch *gdbarch = get_objfile_arch (objfile);
   const int decode_for_pst_p = (pst != NULL);
   struct subfile *last_subfile = NULL, *first_subfile = current_subfile;
+  void (*p_record_line) (struct subfile *subfile, int line, CORE_ADDR pc)
+    = record_line;
 
   baseaddr = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
 
@@ -10445,13 +10455,13 @@ dwarf_decode_lines (struct line_header *
 			{
 			  addr = gdbarch_addr_bits_remove (gdbarch, address);
 			  if (last_subfile)
-			    record_line (last_subfile, 0, addr);
+			    (*p_record_line) (last_subfile, 0, addr);
 			  last_subfile = current_subfile;
 			}
 		      /* Append row to matrix using current values.  */
 		      addr = check_cu_functions (address, cu);
 		      addr = gdbarch_addr_bits_remove (gdbarch, addr);
-		      record_line (current_subfile, line, addr);
+		      (*p_record_line) (current_subfile, line, addr);
 		    }
 		}
 	      basic_block = 0;
@@ -10468,12 +10478,19 @@ dwarf_decode_lines (struct line_header *
 	      switch (extended_op)
 		{
 		case DW_LNE_end_sequence:
+		  p_record_line = record_line;
 		  end_sequence = 1;
 		  break;
 		case DW_LNE_set_address:
 		  address = read_address (abfd, line_ptr, cu, &bytes_read);
 		  op_index = 0;
 		  line_ptr += bytes_read;
+
+		  if (address == 0 && !dwarf2_per_objfile->has_section_at_zero)
+		    /* This line table is for a function which has been
+		       GCd by the linker.  Ignore it.  PR gdb/12528 */
+		    p_record_line = noop_record_line;
+
 		  address += baseaddr;
 		  break;
 		case DW_LNE_define_file:
@@ -10528,12 +10545,12 @@ dwarf_decode_lines (struct line_header *
 			{
 			  addr = gdbarch_addr_bits_remove (gdbarch, address);
 			  if (last_subfile)
-			    record_line (last_subfile, 0, addr);
+			    (*p_record_line) (last_subfile, 0, addr);
 			  last_subfile = current_subfile;
 			}
 		      addr = check_cu_functions (address, cu);
 		      addr = gdbarch_addr_bits_remove (gdbarch, addr);
-		      record_line (current_subfile, line, addr);
+		      (*p_record_line) (current_subfile, line, addr);
 		    }
 		}
 	      basic_block = 0;
@@ -10632,7 +10649,7 @@ dwarf_decode_lines (struct line_header *
           if (!decode_for_pst_p)
 	    {
 	      addr = gdbarch_addr_bits_remove (gdbarch, address);
-	      record_line (current_subfile, 0, addr);
+	      (*p_record_line) (current_subfile, 0, addr);
 	    }
         }
     }
Index: testsuite/gdb.cp/pr12528.cc
===================================================================
RCS file: testsuite/gdb.cp/pr12528.cc
diff -N testsuite/gdb.cp/pr12528.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.cp/pr12528.cc	14 Mar 2011 20:52:11 -0000
@@ -0,0 +1,41 @@
+/* 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/>.
+   */
+
+// Test case for PR gdb/12528
+
+struct foo
+{
+  foo (int x);
+  int _x;
+};
+
+struct foo2 : public foo
+{
+  foo2 (int x);
+};
+
+foo::foo (int x) : _x (x) { }
+
+foo2::foo2 (int x) : foo (x) { }
+
+int
+main ()
+{
+  foo2 bar (3);
+  return 0;
+}
Index: testsuite/gdb.cp/pr12528.exp
===================================================================
RCS file: testsuite/gdb.cp/pr12528.exp
diff -N testsuite/gdb.cp/pr12528.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.cp/pr12528.exp	14 Mar 2011 20:52:11 -0000
@@ -0,0 +1,55 @@
+# 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/>.
+
+# This file is part of the gdb testsuite
+
+# Test casting, especially between class types or pointer-to-class
+# types.
+
+# This file is part of the gdb testsuite
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+#
+# test running programs
+#
+if { [skip_cplus_tests] } { continue }
+
+set testfile "pr12528"
+set srcfile ${testfile}.cc
+set binfile ${objdir}/${subdir}/${testfile}
+
+if [get_compiler_info ${binfile} "c++"] {
+    return -1;
+}
+
+set additional_flags {-ffunction-sections -Wl,--gc-sections}
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable \
+	   [list debug c++ additional_flags=$additional_flags]] != "" } {
+    untested $srcfile
+    return -1
+}
+
+clean_restart $testfile
+
+if { ![runto_main] } {
+    fail "Can't run to main"
+    return
+}
+
+gdb_breakpoint "foo::foo"
+gdb_test "continue" "Breakpoint .*foo::foo.*"