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Re: [PATCH] rs6000: Add a builtin to read the time base register on PowerPC


Point being, for simulator environments, you may not want the
loop that was suggested later.  On the other hand, that might
not be an observable period, either.

I don't think looping a million times would be too slow for the testsuite: there are many tests that do a lot more work than that, already.

The worst case for hardware that I know of can take about 100
clock cycles for one timebase tick.

But how about this then, which only iterates much if the test
fails:


int main (void) { uint64_t t = __builtin_ppc_get_timebase (); int j;

	for (j = 0; j < 1000000; j++)
		if (t != __builtin_ppc_get_timebase ())
			break;

	return (j == 1000000);
}


Segher



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