Re: [patch] Use displaced stepping regardless of SW single step

[Yao Qi <yao at codesourcery dot com>]

On 09/04/2011 09:54 PM, Yao Qi wrote:
> Regression tested on x86_64-unknown-linux-gnu with displaced stepping
> "auto" and "on" respectively.  No extra failures, but there are two
> PASSes changed to KFAILs,
>
>    -PASS: gdb.cp/annota2.exp: watch triggered on a.x
>    +KFAIL: gdb.cp/annota2.exp: watch triggered on a.x (PRMS: gdb/38)
>    -PASS: gdb.cp/annota3.exp: watch triggered on a.x
>    +KFAIL: gdb.cp/annota3.exp: watch triggered on a.x (PRMS: gdb/38)
>
> I am not familiar with this case, so can't tell this is caused by my patch.

I made a mistake when comparing gdb.sum, and I run testsuite again this 
morning, and get something different on x86_64-pc-linux-gnu,

  - When displaced stepping is set to "auto", no regression.
  - When displaced stepping is set to "on", there are some new fails,
    * FAIL: gdb.base/ending-run.exp: step to end of run
      The test case doesn't match the output, while the output is correct.
    * FAIL: gdb.base/gdb1555.exp: Step into shared lib function
      FAIL: gdb.base/gdb1555.exp: Next while in a shared lib function
      FAIL: gdb.base/gnu-ifunc.exp: step
      FAIL: gdb.base/gnu-ifunc.exp: continue to break-at-nextcall
      FAIL: gdb.base/gnu-ifunc.exp: continue to breakpoint: nextcall 
gnu_ifunc
      FAIL: gdb.base/gnu-ifunc.exp: nextcall gnu_ifunc skipped
      These fails are caused by SIGSEGV in gdb, which shows some 
potential bugs in x86 displaced stepping.
    * FAIL: gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (sw)
      FAIL: gdb.threads/pending-step.exp: next in multiple threads with 
breakpoints (timeout)
      They are similar to the problems (#4 and #5) I found on arm 
(posted http://sourceware.org/ml/gdb-patches/2011-08/msg00609.html), and 
I'll post other patches to fix them.

> -&&  (tp->control.trap_expected
> -	  || (step&&  gdbarch_software_single_step_p (gdbarch)))
> +&&  (tp->control.trap_expected || step))

There is an extra ")" added by mistake when I am adding changelog entry 
for this patch.  Here is the right one.

--
Yao (éå)

	gdb/
	* infrun.c (resume): Use displaced stepping regardless of supporting
	software single step.

---
 gdb/infrun.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 7886cce..40e1d71 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1733,8 +1733,7 @@ a command like `return' or `jump' to continue execution."));
      event, displaced stepping breaks the vfork child similarly as single
      step software breakpoint.  */
   if (use_displaced_stepping (gdbarch)
-      && (tp->control.trap_expected
-	  || (step && gdbarch_software_single_step_p (gdbarch)))
+      && (tp->control.trap_expected || step)
       && sig == TARGET_SIGNAL_0
       && !current_inferior ()->waiting_for_vfork_done)
     {
-- 
1.7.0.4