RFR: 8320646: RISC-V: C2 VectorCastHF2F [v3]

[Fei Yang]

On Wed, 28 Feb 2024 14:19:06 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you review this patch to add instrinsics for VectorCastHF2F/VectorCastF2HF?
>> Thanks!
>> 
>> ## Test
>> 
>> test/jdk/java/lang/Float/Binary16ConversionNaN.java
>> test/jdk/java/lang/Float/Binary16Conversion.java
>> 
>> hotspot/jtreg/compiler/intrinsics/float16
>> hotspot/jtreg/compiler/vectorization/TestFloatConversionsVectorjava
>> hotspot/jtreg/compiler/vectorization/TestFloatConversionsVectorNaN.java
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   make UseZvfh experimatal; clean code

src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp line 2003:

> 2001:   // i.e. non-NaN and non-Inf cases.
> 2002: 
> 2003:   vsetvli_helper(BasicType::T_SHORT, length, Assembler::mf2);

Will this `vsetvli` setting work when we check for NaNs in L2005-L2010?  The `Assembler::mf2` param doesn't seem correct to me. Should we use `Assembler::m1` here instead?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17698#discussion_r1509035057