Re: [patch] Re: Advice on fixing gdb/12528

[Paul Pluzhnikov <ppluzhnikov@google.com>]

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On Tue, Mar 15, 2011 at 12:03 PM, Jan Kratochvil
<jan.kratochvil@redhat.com> wrote:

> I would keep it as is, there is only a risk of false PASS, not false FAIL.
> And the real FAIL would be caught by x86*.

Thanks.

I'll commit attached patch tomorrow if there are no further comments.

-- 
Paul Pluzhnikov

ChangeLog:

2011-03-15  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:

2011-03-15  Paul Pluzhnikov  <ppluzhnikov@google.com>

      PR gdb/12528
      * gdb.base/Makefile.in: Adjust EXECUTABLES.
      * gdb.base/break-on-linker-gcd-function.exp: New test.
      * gdb.base/break-on-linker-gcd-function.cc: New file.

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Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.509
diff -u -p -p -u -r1.509 dwarf2read.c
--- dwarf2read.c	15 Mar 2011 15:57:11 -0000	1.509
+++ dwarf2read.c	15 Mar 2011 19:18:30 -0000
@@ -10364,6 +10364,14 @@ 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.
@@ -10399,6 +10407,8 @@ 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));
 
@@ -10468,13 +10478,13 @@ 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;
@@ -10491,12 +10501,24 @@ 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 */
+
+		      complaint (&symfile_complaints,
+				 _(".debug_line section at address 0"));
+		      p_record_line = noop_record_line;
+		    }
+
 		  address += baseaddr;
 		  break;
 		case DW_LNE_define_file:
@@ -10551,12 +10573,12 @@ 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;
@@ -10655,7 +10677,7 @@ 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.base/Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.base/Makefile.in,v
retrieving revision 1.9
diff -u -p -p -u -r1.9 Makefile.in
--- testsuite/gdb.base/Makefile.in	22 Feb 2011 20:52:46 -0000	1.9
+++ testsuite/gdb.base/Makefile.in	15 Mar 2011 19:18:30 -0000
@@ -5,7 +5,8 @@ EXECUTABLES = a2-run advance all-types a
 	annota3 anon args arrayidx async attach attach-pie-misread \
 	attach2 auxv bang\! bfp-test bigcore bitfields bitfields2 \
 	break break-always break-entry break-interp-test breako2 \
-	breakpoint-shadow call-ar-st call-rt-st call-sc-t* call-signals \
+	breakpoint-shadow break-on-linker-gcd-function \
+	call-ar-st call-rt-st call-sc-t* call-signals \
 	call-strs callexit callfuncs callfwmall charset checkpoint \
 	chng-syms code_elim1 code_elim2 commands compiler complex \
 	condbreak consecutive constvars coremaker cursal cvexpr \
Index: testsuite/gdb.base/break-on-linker-gcd-function.cc
===================================================================
RCS file: testsuite/gdb.base/break-on-linker-gcd-function.cc
diff -N testsuite/gdb.base/break-on-linker-gcd-function.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/break-on-linker-gcd-function.cc	15 Mar 2011 19:18:30 -0000
@@ -0,0 +1,32 @@
+/* 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
+
+void
+foo ()
+{
+  // This function is not referenced and should be GCd by the linker
+  return; // gdb break here
+}
+
+int
+main ()
+{
+  return 0;
+}
Index: testsuite/gdb.base/break-on-linker-gcd-function.exp
===================================================================
RCS file: testsuite/gdb.base/break-on-linker-gcd-function.exp
diff -N testsuite/gdb.base/break-on-linker-gcd-function.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/break-on-linker-gcd-function.exp	15 Mar 2011 19:18:30 -0000
@@ -0,0 +1,54 @@
+# 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 "break-on-linker-gcd-function"
+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
+
+# Single hex digit
+set xd {[0-9a-f]}
+
+# This accepts e.g. "Breakpoint 1 at 0x40968a" (fixed GDB)
+# but rejects e.g. "Breakpoint 1 at 0x4" (broken GDB).
+gdb_test "b [gdb_get_line_number "gdb break here"]" "Breakpoint \[0-9\] at 0x${xd}${xd}+: .*"