RFR: 8356281: Fix for TestFPComparison failure due to incorrect result

[Quan Anh Mai]

On Wed, 7 May 2025 16:05:53 GMT, Srinivas Vamsi Parasa <sparasa at openjdk.org> wrote:

> This PR fixes the cause of failure in TestFPComparison while using APX NDD instructions.
> 
> The test passes after using this fix as shown below:
> 
> Passed: compiler/c2/irTests/TestFPComparison.java
> Test results: passed: 1
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR  SKIP   
>    jtreg:test/hotspot/jtreg/compiler/c2/irTests/TestFPComparison.java
>                                                          1     1     0     0     0   
> ==============================
> TEST SUCCESS

src/hotspot/cpu/x86/x86_64.ad line 6273:

> 6271:   ins_cost(200);
> 6272:   format %{ "ecmovpl  $dst, $src1, $src2\n\t"
> 6273:             "cmovnel  $dst, $src2" %}

You need `effect(TEMP dst)` for these nodes, too.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25101#discussion_r2080104541