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[NEWS/RFA] Re: [gdbserver] x86 agent expression bytecode compiler (speed up conditional tracepoints)


On Thursday 10 June 2010 19:43:37, Tom Tromey wrote:
> Pedro> Hmmmm.  This is an implementation detail of gdbserver's fast
> Pedro> tracepoints, and gdbserver fast tracepoints are new in 7.2.  What
> Pedro> would we announce?
> 
> Just mention the JIT in the current paragraph.
> JITting is cool, we should at least publicize it a little.

How about this, then?  Okay?

-- 
Pedro Alves

2010-06-14  Pedro Alves  <pedro@codesourcery.com>

	* NEWS: Mention GDBserver's JIT compilation of tracepoint
	bytecode.

---
 gdb/NEWS |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Index: src/gdb/NEWS
===================================================================
--- src.orig/gdb/NEWS	2010-06-14 11:59:21.000000000 +0100
+++ src/gdb/NEWS	2010-06-14 12:12:54.000000000 +0100
@@ -36,7 +36,14 @@ qRelocInsn
   - GDBserver now support tracepoints (including fast tracepoints).
     The feature is currently supported by the i386-linux and
     amd64-linux builds.  See the "Tracepoints support in gdbserver"
-    section in the manual for more information.
+    section in the manual for more information.  GDBserver JIT
+    compiles the tracepoint's conditional agent expression bytecode
+    into native code whenever possible for low overhead dynamic
+    tracepoints conditionals.  For such tracepoints, an expression
+    that examines program state is evaluated when the tracepoint is
+    reached, in order to determine whether to capture trace data.  If
+    the condition is simple and false, processing the tracepoint
+    finishes very quickly and no data is gathered.
 
   - GDBserver now supports x86_64 Windows 64-bit debugging.
 


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