Hi.
I think, that it is magnificent idea. (Though I never collided with profiling
and I do not use almost a debugger.)
At me the following offers:
1. To add record of the stack pointer.
2. To use harmless commands, for example: BIS/BIC #0,R1
And there is no opportunity directly to transfer into simulator the table of
interesting addresses, not inserting dummy words in a code of the program?
Regards.
As 7 Aug 2004 Dmitry wrote:
> Fellows,
> I came with the following idea:
>
> 1. Background.
> ===========
> Currently, profiling is not implemented in mspgcc and only the way to check
> time/cycles requirements is to count execution cycles in a simulator.
> However, sometimes, I have to count cycles, cause some of my operations are
> life critical and require high optimization.
> The possible optimization in gcc is not suitable for cross-compiling and
> 'small' targets. However, we got gdb's buit in simulator where we can do
> whatever we want.
>
> 2. Idea
> ======
> On _every_ function entry record currect cycle counter. On every function
> exit record cycle counter. Record them along with a function baf_vma
> address. For example:
> We got the following code which utilizes two functions:
> void a() {}
> void b() { ... a(); ...}
> At very first instr of b() record 'b' address. Assume it is 0xbebe.
> At very first instr of a() record 'a' address. Assume it is 0xbaba.
> The same at exit.
> The we'll get following 'trace' information (saved to the file in, say,
> binary format):
> 0xbebe enter [cycle couter]
> 0xbaba enter [cycle couter]
> 0xbaba exit [cycle couter]
> 0xbebe exit [cycle couter]
> Also, this file can (should contain symbols information)
>
> The some external program will analyze this trace and represent call flow.
>
> 3. Implementation:
> ==============
> To achieve this capability, I propose new assembler pseudo operations:
> .profile_enter
> .profile_exit
> Which first one will be placed at the beginning of the function prologue,
> another one -- before 'ret' (reti) instruction in assembly code.
> So, function will look like:
>
> .global f
> .type f, @object
> f:
> .profile_enter
> push r10
> ...
> pop r10
> .profile_exit
> .Lfe1:
> ...........
>
> GNU assembler will substitute some invalid code to the binary file, when
> hits these two pseudo. User can pass these codes to the assembler via
> command line options:
> -mpge 0x0001, -mpgx 0x002 (-e, -x as short options)
> for .profile_enter and .profile_exit respectively.
>
> Then, when this binary runs in a simulator, instead of generation an error
> message, profiling info will be saved.
>
> 4. Current Status:
> ==============
> Assembly part is implemented.
> GCC's part will be done next week.
> Simulator has not been touched.
> GUI for profile information browsing already exists. I wrote it when
> developed a profiler for native gcc profiling (under bsd). This is written
> with QT (www.trolltech.org) and I'll port it to our needs next week. QT is
> a portable stuff and can be ported to M$ windoze with minimum changes.
>
> +++++++++++++++++++++++++++++++++++++
>
> What do you think guys???
>
> Cheers,
> ~d
