[PATCH 2/2] Check function is GC'ed

Yao Qi
2014-08-06T06:54:36Z

I see the following fail on arm-none-eabi target,

(gdb) b 24^M
Breakpoint 1 at 0x4: file
../../../../git/gdb/testsuite/gdb.base/break-on-linker-gcd-function.cc,
line 24.^M
(gdb) FAIL: gdb.base/break-on-linker-gcd-function.exp: b 24

Currently, we are using flag has_section_at_zero to determine whether
address zero in debug info means the corresponding code has been
GC'ed, like this:

case DW_LNE_set_address:
address = read_address (abfd, line_ptr, cu, &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 */

However, this is incorrect on some bare metal targets, as .text
section is located at 0x0. In this patch, we choose 'textlow' field
of partial symtabl. This patch fixes the fail above. It is
regression tested on x86_64-linux, arm-none-eabi,
arm-none-linux-gnueabi. OK to apply?

gdb:

2014-08-06 Yao Qi <yao@codesourcery.com>

* dwarf2read.c (dwarf_decode_lines_1): Skip the line table if
PST->textlow is greater than zero.
---
gdb/dwarf2read.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 8011e4e..5e292f2 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -17229,6 +17229,8 @@ dwarf_decode_lines_1 (struct line_header *lh, const char *comp_dir,
/* Decode the table. */
while (!end_sequence)
{
+ struct partial_symtab *pst = NULL;
+
op_code = read_1_byte (abfd, line_ptr);
line_ptr += 1;
if (line_ptr > line_end)
@@ -17291,7 +17293,12 @@ dwarf_decode_lines_1 (struct line_header *lh, const char *comp_dir,
case DW_LNE_set_address:
address = read_address (abfd, line_ptr, cu, &bytes_read);

- if (address == 0 && !dwarf2_per_objfile->has_section_at_zero)
+ if (!decode_for_pst_p)
+ pst = cu->per_cu->v.psymtab;
+
+ if (address == 0
+ && (!dwarf2_per_objfile->has_section_at_zero
+ || (pst != NULL && pst->textlow > address)))
{
/* This line table is for a function which has been
GCd by the linker. Ignore it. PR gdb/12528 */
--
1.9.0