On Sun, 9 Aug 2026 08:54:53 GMT, Andrew Haley <[email protected]> wrote:
>> Shawn Emery has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> Emulate production operations via EC lookups
>
> test/micro/org/openjdk/bench/javax/crypto/full/PolynomialP256Bench.java line
> 139:
>
>> 137: // prevent constant folding. Previously, C2 would perform
>> constant
>> 138: // propagation and remove the subsequent dead-code where 0 was
>> input.
>> 139: for (int j = 0; j < SET; j++) {
>
> We could just do this:
>
>
> MutableIntegerModuloP test1 = X.mutable();
> MutableIntegerModuloP test2 = one.mutable();
> for (int i = 0; i< 10000; i++) {
> int bits = i * 2654435769u;
> test1.conditionalSet(test2, bits & (1 << 24)); // The exact bit
> numbers don't matter, but don't use the low bits
> test1.conditionalSet(test2, bits & (2 << 24));
> test2.conditionalSet(test1, bits & (4 << 24));
> test2.conditionalSet(test1, bits & (8 << 24));
>
>
> which should get us something unbiased and unpredictable.
Unfortunately this change would reintroduce cross-call and dead-code
elimination with C2, while still biasing against opaqueness with intrinsics.
I've spent the past week going through different designs to keep the benchmark
relatively close to the original, like you have, with the goal of preventing
optimizations. For better or for worse, C2 is too good at identifying targets
and will quite elegantly remove any code that doesn't contribute to said target.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/32047#discussion_r3745506332
