[1/2] gdb, linespec: avoid multiple locations with same PC
Checks
| Context |
Check |
Description |
| linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 |
success
|
Build passed
|
| linaro-tcwg-bot/tcwg_gdb_build--master-arm |
success
|
Build passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 |
success
|
Test passed
|
| linaro-tcwg-bot/tcwg_gdb_check--master-arm |
success
|
Test passed
|
Commit Message
From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>
Setting a BP on a line like this would incorrectly yield two BP locations:
01 void two () { {int var = 0;} }
(gdb) break 1
Breakpoint 1 at 0x1164: main.cpp:1. (2 locations)
(gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y <MULTIPLE>
1.1 y 0x0000000000001164 in two() at main.cpp:1
1.2 y 0x0000000000001164 in two() at main.cpp:1
In this case decode_digits_ordinary () returns two SALs, exactly matching the
requested line. One for the entry PC and one for the prologue end PC. This was
tested with GCC, CLANG and ICPX. Subsequent code tries to skip the prologue
on these PCs, which in turn makes them the same.
To fix this, ignore SALs with the same PC and program space when adding to the
list of SALs.
This will then properly set only one location:
(gdb) break 1
Breakpoint 1 at 0x1164: file main.cpp, line 1
(gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y 0x0000000000001164 in two() at main.cpp:1
---
gdb/linespec.c | 6 ++++++
gdb/testsuite/gdb.linespec/linespec.exp | 6 ++++++
gdb/testsuite/gdb.linespec/lspec.cc | 2 ++
3 files changed, 14 insertions(+)
Comments
On Fri, Oct 18, 2024 at 12:22 PM Klaus Gerlicher <klaus.gerlicher@intel.com>
wrote:
> From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>
>
> Setting a BP on a line like this would incorrectly yield two BP locations:
>
> 01 void two () { {int var = 0;} }
>
> (gdb) break 1
> Breakpoint 1 at 0x1164: main.cpp:1. (2 locations)
>
> (gdb) info breakpoints
> Num Type Disp Enb Address What
> 1 breakpoint keep y <MULTIPLE>
> 1.1 y 0x0000000000001164 in two() at main.cpp:1
> 1.2 y 0x0000000000001164 in two() at main.cpp:1
>
> In this case decode_digits_ordinary () returns two SALs, exactly matching
> the
> requested line. One for the entry PC and one for the prologue end PC.
> This was
> tested with GCC, CLANG and ICPX. Subsequent code tries to skip the
> prologue
> on these PCs, which in turn makes them the same.
>
> To fix this, ignore SALs with the same PC and program space when adding to
> the
> list of SALs.
>
> This will then properly set only one location:
>
> (gdb) break 1
> Breakpoint 1 at 0x1164: file main.cpp, line 1
>
> (gdb) info breakpoints
> Num Type Disp Enb Address What
> 1 breakpoint keep y 0x0000000000001164 in two() at main.cpp:1
> ---
> gdb/linespec.c | 6 ++++++
> gdb/testsuite/gdb.linespec/linespec.exp | 6 ++++++
> gdb/testsuite/gdb.linespec/lspec.cc | 2 ++
> 3 files changed, 14 insertions(+)
>
>
> Hi Klaus,
it's great you fixed this issue and extended the linespec test. I can also
confirm this change adds no regressions for
Fedora Rawhide x86_64.
Reviewed-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>
@@ -1047,6 +1047,12 @@ add_sal_to_sals (struct linespec_state *self,
struct symtab_and_line *sal,
const char *symname, int literal_canonical)
{
+ /* We don't want two SALs with the same PC from the
+ same program space. */
+ for (const auto &s : *sals)
+ if (sal->pc == s.pc && sal->pspace == s.pspace)
+ return;
+
sals->push_back (*sal);
if (self->canonical)
@@ -194,6 +194,12 @@ gdb_test "break lspec.h:$line" \
"Breakpoint \[0-9\]+ at $hex: file .*lspec.h, line $line." \
"set breakpoint in f1"
+# This should only have a single location -- in no_multi_locs.
+set line [gdb_get_line_number no_multi_locs]
+gdb_test "break $line" \
+ "Breakpoint \[0-9\]+ at $hex: file .*$srcfile, line $line." \
+ "set breakpoint at no_multi_locs"
+
#
# Multi-inferior tests.
#
@@ -13,6 +13,8 @@ int body_elsewhere()
#include "body.h"
}
+void no_multi_locs () { {int var = 0;} }
+
int main()
{
return dupname(0) + m(0) + n(0) + f1() + f2() + body_elsewhere();