non-contiguous files break dwarf2 init-file recognition

Alexandre Oliva
2002-12-11T22:19:05Z

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If an object file contains functions in CODE sections that are mapped
to different segments, or just non-contiguous memory areas, and the
entry point of the program happens to be in between such areas, we may
end up picking the wrong comp_unit as init file. This patch fixes it
(as long as the code of the init file itself is contiguous, this
should be fine, otherwise the whole thing has to be redesigned). Ok
to install?

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Index: gdb/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>

* dwarf2read.c (read_file_scope): Handle non-contiguous
comp_units, testing entry_point for every subprogram.

Index: gdb/dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.78
diff -u -p -r1.78 dwarf2read.c
--- gdb/dwarf2read.c 11 Dec 2002 20:55:37 -0000 1.78
+++ gdb/dwarf2read.c 11 Dec 2002 21:42:29 -0000
@@ -1710,9 +1710,15 @@ read_file_scope (struct die_info *die, s
struct die_info *child_die;
bfd *abfd = objfile->obfd;
struct line_header *line_header = 0;
+ CORE_ADDR entry_point = objfile->ei.entry_point - baseaddr;
+ int init_file = 0;

if (!dwarf2_get_pc_bounds (die, &lowpc, &highpc, objfile))
{
+ if (entry_point >= lowpc && entry_point < highpc
+ && lowpc != ((CORE_ADDR) -1))
+ init_file = 1;
+
if (die->has_children)
{
child_die = die->next;
@@ -1724,6 +1730,17 @@ read_file_scope (struct die_info *die, s

if (dwarf2_get_pc_bounds (child_die, &low, &high, objfile))
{
+ /* We want to do this test per subprogram, so
+ that, if the comp_unit is not contiguous
+ (e.g., it has code in several sections that
+ are not mapped to a single segment, such that
+ there is code from other comp_units
+ interspersed with code from this one), we
+ don't get false positives. */
+ if (entry_point >= low && entry_point < high
+ && lowpc != ((CORE_ADDR) -1))
+ init_file = 1;
+
lowpc = min (lowpc, low);
highpc = max (highpc, high);
}
@@ -1760,8 +1777,7 @@ read_file_scope (struct die_info *die, s
}
}

- if (objfile->ei.entry_point >= lowpc &&
- objfile->ei.entry_point < highpc)
+ if (init_file)
{
objfile->ei.entry_file_lowpc = lowpc;
objfile->ei.entry_file_highpc = highpc;

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--
Alexandre Oliva Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist Professional serial bug killer