RFR: 8338694: x86_64 intrinsic for tanh using libm [v3]

[Sandhya Viswanathan]

On Thu, 5 Sep 2024 19:10:34 GMT, Srinivas Vamsi Parasa <duke at openjdk.org> wrote:

>> The goal of this PR is to implement an x86_64 intrinsic for java.lang.Math.tanh() using libm
>> 
>> Benchmark (ops/ms) | Stock JDK | Tanh intrinsic | Speedup
>> -- | -- | -- | --
>> MathBench.tanhDouble | 70900 | 95618 | 1.35x
>
> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   update libm tanh reference test with code review suggestions

src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp line 810:

> 808:       x->id() == vmIntrinsics::_dpow || x->id() == vmIntrinsics::_dcos ||
> 809:       x->id() == vmIntrinsics::_dsin || x->id() == vmIntrinsics::_dtan ||
> 810:       x->id() == vmIntrinsics::_dlog10 || x->id() == vmIntrinsics::_dtanh) {

Need to have the tanh under #Ifdef _LP64 as we are generating stub only for 64 bit.

src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp line 1000:

> 998:        if (StubRoutines::dtanh() != nullptr) {
> 999:         __ call_runtime_leaf(StubRoutines::dtanh(), getThreadTemp(), result_reg, cc->args());
> 1000:       } // TODO: else clause?

You could instead have an assert here that StubRoutines::dtanh() is not null. Thereby no need for the else clause.

src/hotspot/cpu/x86/templateInterpreterGenerator_x86_32.cpp line 376:

> 374:   //        [ hi(arg) ]
> 375:   //
> 376:   if (kind == Interpreter::java_lang_math_tanh) {

Need to update the copyright year to 2024 in this file.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20657#discussion_r1752286133
PR Review Comment: https://git.openjdk.org/jdk/pull/20657#discussion_r1752289575
PR Review Comment: https://git.openjdk.org/jdk/pull/20657#discussion_r1752304061