Re: tracepoint maintainance models

[Frank Ch. Eigler]

Hi -

On Fri, Oct 06, 2006 at 01:33:11AM -0400, Steven Rostedt wrote:
> Coming into this really late, and I'm still behind in reading this and
> related threads, but I want to throw this idea out, and it's getting
> late.
> [...]
> #define MARK(label, var)			\
> 	asm ("debug_" #label ":\n"		\
> 	     ".section .data\n"			\
> 	     #label "_" #var ": xor %0,%0\n"	\
> 	     ".previous" : : "r"(var))
> [...]
> $ gcc -O2 -o mark mark.c
> $ ./mark
> func y is in reg B at 0x80483ce
> [...]

Clever.

> Now the question is, isn't MARK() in this code a non intrusive marker?

Not quite.  The assembly code forces gcc to materialize the data that
it might already have inlined, and to borrow a register for the
duration.  It's still a neat idea though.

- FChE
-
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