> On 2010-08-17 14:56:45, Ali Saidi wrote: > > src/base/intmath.hh, line 84 > > <http://reviews.m5sim.org/r/164/diff/1/?file=1817#file1817line84> > > > > How about a warning if it's called with an exponent > 20? > > > > Steve Reinhardt wrote: > I'd prefer something a little more robust. One option is to track old > and new result values in the loop, and warn if new_result < old_result. > Another option is just to do it in FP by calling pow(), then verify that the > result is something that can be safely cast back to a uint64_t. (I like that > second one, to be honest, assuming that this isn't called that frequently.) > The advantage of the first one is that if you actually do care about > performance, you could code it up in such a way that the test is only done in > debug mode. However I don't recommend that unless you're really doing this > every 10 ticks. > > Ali Saidi wrote: > I have a warning if exp > 20 and a check old_val < result on every > iteration of the loop. sound good?
I considered adding that to my example code above, but then it seemed that the calculation could overflow over and over and spew warnings. Also, isn't it possible to overflow but still end up with a larger value? I don't think it would be that difficult to find a case. Getting a warning sometimes would be nice if it catches a problem, but if it doesn't it could give a false sense of security. The FP suggestion seems a lot safer, but then too I imagine you could end up having to round (you will, if you have a truely 64 bit integer) and getting something that doesn't actually overflow but that fails the test. - Gabe ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://reviews.m5sim.org/r/164/#review210 ----------------------------------------------------------- On 2010-08-13 09:44:12, Ali Saidi wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://reviews.m5sim.org/r/164/ > ----------------------------------------------------------- > > (Updated 2010-08-13 09:44:12) > > > Review request for Default. > > > Summary > ------- > > ARM: Add I/O devices for booting linux > > > Diffs > ----- > > src/base/intmath.hh 3c48b2b3cb83 > src/dev/arm/RealView.py PRE-CREATION > src/dev/arm/SConscript 3c48b2b3cb83 > src/dev/arm/Versatile.py 3c48b2b3cb83 > src/dev/arm/amba_device.hh PRE-CREATION > src/dev/arm/amba_device.cc PRE-CREATION > src/dev/arm/amba_fake.hh PRE-CREATION > src/dev/arm/amba_fake.cc PRE-CREATION > src/dev/arm/gic.hh PRE-CREATION > src/dev/arm/gic.cc PRE-CREATION > src/dev/arm/pl011.hh PRE-CREATION > src/dev/arm/pl011.cc PRE-CREATION > src/dev/arm/realview.hh PRE-CREATION > src/dev/arm/realview.cc PRE-CREATION > src/dev/arm/rv_ctrl.hh PRE-CREATION > src/dev/arm/rv_ctrl.cc PRE-CREATION > src/dev/arm/timer_sp804.hh PRE-CREATION > src/dev/arm/timer_sp804.cc PRE-CREATION > src/dev/arm/versatile.hh 3c48b2b3cb83 > src/dev/arm/versatile.cc 3c48b2b3cb83 > > Diff: http://reviews.m5sim.org/r/164/diff > > > Testing > ------- > > > Thanks, > > Ali > > _______________________________________________ m5-dev mailing list m5-dev@m5sim.org http://m5sim.org/mailman/listinfo/m5-dev
