[J-core] Debug jump log?
cr88192 at gmail.com
Sat Feb 25 21:49:34 EST 2017
On 2/25/2017 6:40 PM, D. Jeff Dionne wrote:
> On Feb 26, 2017, at 09:00, Rob Landley <rob at landley.net> wrote:
>> How do you reconstruct "three functions back we did fifty-seven iterations of the loop that decided where to go next"?
> You just reconstruct the jump log from the trace. A register doesn't help you with any of this, you need an external interface. If you're really (only) interested in looking at the 9k instruction cycles for interrupts, the better approach is gprof.
> A trace log system is for reconstructing whole program flows, including things like stalls and cache misses...
seems like it could be possible to have a feature to generate an
interrupt whenever a branch occurs, so that the PC could be recorded?
program is running, magic bit set to 1 (possibly in SR?);
hits a branch, triggers interrupt, clears SR bit;
interrupt handler records PC (or does whatever else);
return restores SR, which causes an interrupt on the next branch;
off-hand, I don't really know what ColdFire does (not looked much into it).
(otherwise, sorry, not trying to make an issue here, nor distract too
much from the topic at hand).
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