Re: [PATCH 2/3] skip_prolgoue (amd64)

[Yao Qi <yao at codesourcery dot com>]

On 12/02/2013 03:32 PM, Yao Qi wrote:
> GDB target cache contains both code cache and stack cache.  GDB can
> know the JIT event by means of jit event breakpoint, but GDB can't know
> whether a thread's stack is modified (by other threads).  So we have
> to flush target cache before handling*every*  event :-/  I'll send a
> follow-up patch.

When I finished the patch below, I wondered whether this is the right
way to go.

Nowadays, in non-stop mode, GDB flushes target cache between
each command.  With the patch applied, GDB flushes target cache between
each event.  Then, I realize that GDB flushes cache at any changes (GDB 
commands from user and events from inferior) in non-stop mode, so I 
can't figure out a case that cache can be used.  Do we still need target
cache in non-stop mode?

--
Yao (éå)

Subject: [PATCH] Flush target dcache in non-stop before handling events

gdb:

2013-12-04  Yao Qi  <yao@codesourcery.com>

	* infrun.c: Include "target-dcache.h".
	(fetch_inferior_event): Call target_dcache_invalidate in
	non-stop.
---
 gdb/infrun.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/gdb/infrun.c b/gdb/infrun.c
index 3b55583..2ed0537 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -60,6 +60,7 @@
 #include "objfiles.h"
 #include "completer.h"
 #include "target-descriptions.h"
+#include "target-dcache.h"

 /* Prototypes for local functions */

@@ -2806,6 +2807,16 @@ fetch_inferior_event (void *client_data)

   overlay_cache_invalid = 1;

+  if (non_stop)
+    {
+      /* In non-stop mode, one thread stops and caches the contents of
+	 stack or code, while other running threads may change the
+	 code (through JIT) or stack.  The target cache can get stale
+	 without us being able to detect it.  Flush target cache
+	 before handling each event.  */
+      target_dcache_invalidate ();
+    }
+
   make_cleanup_restore_integer (&execution_direction);
   execution_direction = target_execution_direction ();

--
1.7.7.6