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

Pedro Alves
2010-06-14T11:15:54Z

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.