Re: [PATCH] Fast tracepoints

[Tom Tromey <tromey@redhat.com>]

>>>>> "Stan" == Stan Shebs <stan@codesourcery.com> writes:

Stan> This patch adds "fast" tracepoints to GDB.

Neat.

Stan> Most of the interesting trickery is on the target side - but don't
Stan> despair, Pedro has upcoming patches for a free version using gdbserver
Stan> and a special library.

I wonder whether this could somehow work with systemtap probe points.

Stan> + static void
Stan> + check_fast_tracepoint_sals (struct symtabs_and_lines *sals)
[...]
Stan> +       if (!gdbarch_fast_tracepoint_valid_at (get_current_arch (),
Stan> + 					     sal->pc, NULL))
Stan> + 	error (_("May not have a fast tracepoint at 0x%s"),
Stan> + 	       paddress (get_current_arch (), sal->pc));

Stan> + static int
Stan> + i386_fast_tracepoint_valid_at (struct gdbarch *gdbarch,
Stan> + 			       CORE_ADDR addr, int *isize)
[...]
Stan> +       printf_filtered (_("Instruction at 0x%s is only %d bytes long, need at least %d bytes for the fast tracepoint jump\n"),
Stan> + 		       paddress (gdbarch, addr), len, jumplen);

It seems like it would be nicer for the user if the _at method returned
a reason, so that it could be printed as "May not have a fast
tracepoint: ... : reason".

Similarly, it seems a little strange to me that a predicate function is
expected to print a warning.

Tom