[RFA/DWARF] Do not load .eh_frame section from separete object files

Joel Brobecker
2011-07-01T18:01:46Z

From: Joel Brobecker <brobecker@adacore.com>

We don't need to read the .eh_frame section from the separate
object files, because this data is already present in the
main executable (it needs to, or the program wouldn't work).

We discovered this investigating a problem with the 'next' command,
which was due to unwind failures, which came from the fact that
the .eh_frame was incorrectly relocated. That problem is mostly
under control, I think, but this is a nice optimization in any case.

gdb/ChangeLog (Tristan Gingold):

* dwarf2-frame.c (dwarf2_build_frame_info): Do not load .eh_frame
section in separate object files.

Tested on x86_64-linux as well as x86_64-darwin. OK to commit?

Thanks,
--
Joel

---
gdb/dwarf2-frame.c | 67 ++++++++++++++++++++++++++++------------------------
1 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/gdb/dwarf2-frame.c b/gdb/dwarf2-frame.c
index 5df3488..b68a773 100644
--- a/gdb/dwarf2-frame.c
+++ b/gdb/dwarf2-frame.c
@@ -2227,39 +2227,44 @@ dwarf2_build_frame_info (struct objfile *objfile)
unit->dbase = 0;
unit->tbase = 0;

- dwarf2_get_section_info (objfile, DWARF2_EH_FRAME,
- &unit->dwarf_frame_section,
- &unit->dwarf_frame_buffer,
- &unit->dwarf_frame_size);
- if (unit->dwarf_frame_size)
+ if (objfile->separate_debug_objfile_backlink == NULL)
{
- asection *got, *txt;
-
- /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
- that is used for the i386/amd64 target, which currently is
- the only target in GCC that supports/uses the
- DW_EH_PE_datarel encoding. */
- got = bfd_get_section_by_name (unit->abfd, ".got");
- if (got)
- unit->dbase = got->vma;
-
- /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
- so far. */
- txt = bfd_get_section_by_name (unit->abfd, ".text");
- if (txt)
- unit->tbase = txt->vma;
-
- frame_ptr = unit->dwarf_frame_buffer;
- while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
- frame_ptr = decode_frame_entry (unit, frame_ptr, 1,
- &cie_table, &fde_table);
-
- if (cie_table.num_entries != 0)
+ /* Do not read .eh_frame from separate file as they must be also
+ present in the main file. */
+ dwarf2_get_section_info (objfile, DWARF2_EH_FRAME,
+ &unit->dwarf_frame_section,
+ &unit->dwarf_frame_buffer,
+ &unit->dwarf_frame_size);
+ if (unit->dwarf_frame_size)
{
- /* Reinit cie_table: debug_frame has different CIEs. */
- xfree (cie_table.entries);
- cie_table.num_entries = 0;
- cie_table.entries = NULL;
+ asection *got, *txt;
+
+ /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
+ that is used for the i386/amd64 target, which currently is
+ the only target in GCC that supports/uses the
+ DW_EH_PE_datarel encoding. */
+ got = bfd_get_section_by_name (unit->abfd, ".got");
+ if (got)
+ unit->dbase = got->vma;
+
+ /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
+ so far. */
+ txt = bfd_get_section_by_name (unit->abfd, ".text");
+ if (txt)
+ unit->tbase = txt->vma;
+
+ frame_ptr = unit->dwarf_frame_buffer;
+ while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
+ frame_ptr = decode_frame_entry (unit, frame_ptr, 1,
+ &cie_table, &fde_table);
+
+ if (cie_table.num_entries != 0)
+ {
+ /* Reinit cie_table: debug_frame has different CIEs. */
+ xfree (cie_table.entries);
+ cie_table.num_entries = 0;
+ cie_table.entries = NULL;
+ }
}
}

--
1.7.1