http://sourceware.org/ml/gdb-patches/2012-03/msg00357.html
Subject: [patch 1/2] Fix gdb.cp/gdb2495.exp regression with gcc-4.7 #5

Hi,

posted as a new thread.

As described in
	cancel: [patch] Fix gdb.cp/gdb2495.exp regression with gcc-4.7 #4 [Re: [revert] Regression on PowerPC]
	http://sourceware.org/ml/gdb-patches/2012-03/msg00322.html
just ON_STACK had some regressions.

The expectations in that mail were wrong (at least that cleanup/fix is not
required for gdb.cp/gdb2495.exp).

The problem is that the inferior call return pad breakpoint instruction is
never removed even after inferior call finishes.  It is even still visible in
"maintenance info breakpoints".  This does not matter much for AT_ENTRY_POINT
but for ON_STACK it just corrupts stack.

No regressions on
{x86_64,x86_64-m32,i686}-fedora(15-rawhide)/rhel(5-6)-linux-gnu and for
gdbsever non-extended mode.


Thanks,
Jan


gdb/
2012-03-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Remove momentary breakpoints for completed inferior calls.
	* dummy-frame.c: Include gdbthread.h.
	(pop_dummy_frame_bpt): New function.
	(pop_dummy_frame): Initialie DUMMY earlier.  Call pop_dummy_frame_bpt.

gdb/testsuite/
2012-03-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Remove momentary breakpoints for completed inferior calls.
	* gdb.base/call-signal-resume.exp (maintenance print dummy-frames)
	(maintenance info breakpoints): New tests.

Index: gdb-7.4.50.20120602/gdb/dummy-frame.c
===================================================================
--- gdb-7.4.50.20120602.orig/gdb/dummy-frame.c	2012-01-04 09:17:00.000000000 +0100
+++ gdb-7.4.50.20120602/gdb/dummy-frame.c	2012-06-02 20:42:40.907720327 +0200
@@ -29,6 +29,7 @@
 #include "gdbcmd.h"
 #include "gdb_string.h"
 #include "observer.h"
+#include "gdbthread.h"
 
 /* Dummy frame.  This saves the processor state just prior to setting
    up the inferior function call.  Older targets save the registers
@@ -108,19 +109,36 @@ remove_dummy_frame (struct dummy_frame *
   xfree (dummy);
 }
 
+/* Delete any breakpoint B which is a momentary breakpoint for return from
+   inferior call matching DUMMY_VOIDP.  */
+
+static int
+pop_dummy_frame_bpt (struct breakpoint *b, void *dummy_voidp)
+{
+  struct dummy_frame *dummy = dummy_voidp;
+
+  if (b->disposition == disp_del && frame_id_eq (b->frame_id, dummy->id)
+      && b->thread == pid_to_thread_id (inferior_ptid))
+    delete_breakpoint (b);
+
+  /* Continue the traversal.  */
+  return 0;
+}
+
 /* Pop *DUMMY_PTR, restoring program state to that before the
    frame was created.  */
 
 static void
 pop_dummy_frame (struct dummy_frame **dummy_ptr)
 {
-  struct dummy_frame *dummy;
+  struct dummy_frame *dummy = *dummy_ptr;
+
+  restore_infcall_suspend_state (dummy->caller_state);
 
-  restore_infcall_suspend_state ((*dummy_ptr)->caller_state);
+  iterate_over_breakpoints (pop_dummy_frame_bpt, dummy);
 
   /* restore_infcall_control_state frees inf_state,
      all that remains is to pop *dummy_ptr.  */
-  dummy = *dummy_ptr;
   *dummy_ptr = dummy->next;
   xfree (dummy);
 
Index: gdb-7.4.50.20120602/gdb/testsuite/gdb.base/call-signal-resume.exp
===================================================================
--- gdb-7.4.50.20120602.orig/gdb/testsuite/gdb.base/call-signal-resume.exp	2012-01-23 18:11:50.000000000 +0100
+++ gdb-7.4.50.20120602/gdb/testsuite/gdb.base/call-signal-resume.exp	2012-06-02 20:43:10.523709052 +0200
@@ -101,6 +101,18 @@ gdb_test "frame $frame_number" ".*"
 gdb_test_no_output "set confirm off"
 gdb_test "return" ""
 
+# Verify there are no remains of the dummy frame.
+gdb_test_no_output "maintenance print dummy-frames"
+set test "maintenance info breakpoints"
+gdb_test_multiple $test $test {
+    -re "call dummy.*\r\n$gdb_prompt $" {
+	fail $test
+    }
+    -re "\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
 # Resume execution, the program should continue without any signal.
 
 gdb_test "break stop_two" "Breakpoint \[0-9\]* at .*"