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[v8,06/10] gdb: Skip trampoline functions for the up command.

Message ID 20240524154032.12652-7-abdul.b.ijaz@intel.com
State New
Headers
Series GDB support for DW_AT_trampoline |

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Commit Message

Abdul Basit Ijaz May 24, 2024, 3:40 p.m. UTC 
  From: "Ijaz, Abdul B" <abdul.b.ijaz@intel.com>

This change skips trampoline functions when the option
'skip-trampoline-functions' is set to 'on' for the up command.  Before this
change, GDB processes trampoline functions indicated by the compiler with
DIE "DW_AT_trampoline" and stops at the trampoline function for the 'up'
command.  For better user experience, all such frames can be
skipped and hidden from the user.

In this example the IFX compiler emits "DW_AT_trampoline" tag for the 'first'
and 'second' trampoline functions like following:

function second (x, y) result(z)
  integer, intent(in) :: x, y
  integer :: z
  z = x * y ! breakpt-up
end function second

function first (num1, num2) result(total)
  integer, intent(in) :: num1, num2
  integer  :: total
  total = second (num1 + 4, num2 * 3) ! first-breakpt
  total = total + 30
end function first

Related Dwarf:

0x0000013f:   DW_TAG_subprogram
                DW_AT_low_pc    (0x0000000000404350)
                DW_AT_high_pc   (0x000000000040435f)
                DW_AT_frame_base        (DW_OP_reg6 RBP)
                DW_AT_linkage_name      ("second_.t74p.t75p")
                DW_AT_name      ("second_.t74p.t75p")
                DW_AT_trampoline        ("second_")

0x0000015a:   DW_TAG_subprogram
                DW_AT_low_pc    (0x00000000004044a0)
                DW_AT_high_pc   (0x00000000004044af)
                DW_AT_frame_base        (DW_OP_reg6 RBP)
                DW_AT_linkage_name      ("first_.t104p.t105p")
                DW_AT_name      ("first_.t104p.t105p")
                DW_AT_trampoline        ("first_")

Before this change, the 'up' command output looks like:

'''
(gdb) up
\#1  0x0000000000405209 in second_.t74p.t75p () at test.f90:12
12      end function first
'''

After this change:

'''
(gdb) up
\#2  0x00000000004051e3 in first (num1=16, num2=3) at test.f90:10
10        total = second (num1 + 4, num2 * 3) ! first-breakpt
'''

The test gdb.fortran/func-trampoline.exp is updated for testing this change.

2024-05-24 Ijaz, Abdul B <abdul.b.ijaz@intel.com>
---
 gdb/doc/gdb.texinfo                           |  2 +-
 gdb/stack.c                                   |  7 +++++++
 gdb/testsuite/gdb.fortran/func-trampoline.exp | 12 ++++++++++--
 3 files changed, 18 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 807cedcd91e..d04f3c718d2 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -6538,7 +6538,7 @@  DWARF trampolines marked via DW_AT_trampoline are supported by this.
 When issuing a @code{backtrace}, if @code{skip-trampoline-functions} is set,
 @value{GDBN} will skip trampoline frames while printing the stack.
 
-When issuing a @code{finish} or @code{reverse-finish}, if
+When issuing a @code{finish}, @code{reverse-finish} or @code{up}, if
 @code{skip-trampoline-functions} is set, @value{GDBN} will skip trampoline
 frames while returning from the target function.
 
diff --git a/gdb/stack.c b/gdb/stack.c
index de8b404365f..5dad1fe503a 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -2635,6 +2635,13 @@  up_silently_base (const char *count_exp)
   frame = find_relative_frame (get_selected_frame ("No stack."), &count);
   if (count != 0 && count_exp == NULL)
     error (_("Initial frame selected; you cannot go up."));
+
+  if (skip_trampoline_functions)
+    {
+      for (int i = 0; (SAFE_TRAMPOLINE_CHAIN (i, frame)
+		       && in_trampoline_frame (frame)); ++i)
+	frame = get_prev_frame (frame);
+    }
   select_frame (frame);
 }
 
diff --git a/gdb/testsuite/gdb.fortran/func-trampoline.exp b/gdb/testsuite/gdb.fortran/func-trampoline.exp
index 4cb9e4f4919..e7e4c8ae7b0 100644
--- a/gdb/testsuite/gdb.fortran/func-trampoline.exp
+++ b/gdb/testsuite/gdb.fortran/func-trampoline.exp
@@ -13,8 +13,8 @@ 
 # 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 "backtrace", "backtrace -n" and "finish"  commands for functions with
-# trampoline calls.
+# Test "backtrace", "backtrace -n", "finish" and "up"  commands for
+# functions with trampoline calls.
 
 require allow_fortran_tests
 
@@ -84,3 +84,11 @@  with_test_prefix "finish" {
 	"${fill}first \\(num1=16, num2=3\\)${fill}" \
 	"${fill}(\r\nValue returned is $valnum_re = 180)"]
 }
+
+with_test_prefix "up" {
+    init_test
+
+    gdb_test "up" [multi_line \
+	"#$decimal.* $middle_desc" \
+	"${fill}first = second \\(num1 \\+ 4, num2 \\* 3\\).*${fill}"]
+}