On Thursday, 27 October 2022 at 17:17:01 UTC, ab wrote:
Hi,
when trying to compare different implementations of the
optimized builds of a pure function using benchmark from
std.datetime.stopwatch, I get times equal to zero, I suppose
because the functions are not executed as they do not have side
effects.
The same happens with the example from the documentation:
https://dlang.org/library/std/datetime/stopwatch/benchmark.html
How can I prevent the compiler from removing the code I want to
measure? Is there some utility in the standard library or
pragma that I should use?
Thanks
AB
Thanks to H.S. Teoh and Dennis for the suggestions, they both
work. I like the empty asm block a bit more because it is less
invasive, but it only works with ldc.
@Imperatorn see Dennis code for an example.
std.datetime.benchmark works, but at high optimization level
(-O2, -O3) the loop can be removed and the time brought down to
0hnsec. E.g. try "ldc2 -O3 -run dennis.d".
AB
