RFR: 8357982: Fix several failing BMI tests with -XX:+UseAPX [v7]

[Sandhya Viswanathan]

On Thu, 5 Jun 2025 08:08:48 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> A) Patch extends the following tests with hard-coded encoding checks for various BMI instructions to cover REX2 or extended EVEX encodings supported by APX. 
>> 
>> 
>>      compiler/intrinsics/bmi/verifycode/AndnTestI.java
>>      compiler/intrinsics/bmi/verifycode/AndnTestL.java
>>      compiler/intrinsics/bmi/verifycode/BzhiTestI2L.java
>>      compiler/intrinsics/bmi/verifycode/LZcntTestL.java
>>      compiler/intrinsics/bmi/verifycode/TZcntTestL.java
>> 
>> 
>> B) After integration of JDK-8349582, which added APX NDD support, AndN instruction selection patterns that expect (Xor SRC, -1) as one of its operands were not getting selected because of a lower-cost generic immediate pattern match; patch fixes this issue through strict predicate checks.
>> 
>> Above tests are now passing, validations were carried out using Intel Software Development emulator.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review resolutions

test/hotspot/jtreg/compiler/intrinsics/bmi/verifycode/LZcntTestI.java line 57:

> 55:         // REX2 variant
> 56:         instrMaskAPX = new byte[]{(byte) 0xFF, (byte)0x80, (byte) 0xFF};
> 57:         instrPatternAPX = new byte[]{(byte) 0xD5, (byte) 0x80, (byte) 0xBD};

I think we should check for 0xF3 as well here for lzcnt to differentiate it from bsr:
instrMaskAPX = new byte[]{(byte) 0xFF, (byte) 0xFF, (byte)0x80, (byte) 0xFF};
instrPatternAPX = new byte[]{(byte) 0xF3, (byte) 0xD5, (byte) 0x80, (byte) 0xBD};

test/hotspot/jtreg/compiler/intrinsics/bmi/verifycode/TZcntTestI.java line 56:

> 54:         // REX2 variant
> 55:         instrMaskAPX = new byte[]{(byte) 0xFF, (byte)0x80, (byte) 0xFF};
> 56:         instrPatternAPX = new byte[]{(byte) 0xD5, (byte) 0x80, (byte) 0xBC};

I think we should check for 0xF3 as well here for tzcnt to differentiate it from bsf:
       instrMaskAPX = new byte[]{(byte) 0xFF, (byte) 0xFF,  (byte)0x80, (byte) 0xFF};
       instrPatternAPX = new byte[]{(byte) 0xF3, (byte) 0xD5, (byte) 0x80, (byte) 0xBC};

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PR Review Comment: https://git.openjdk.org/jdk/pull/25501#discussion_r2130968611
PR Review Comment: https://git.openjdk.org/jdk/pull/25501#discussion_r2130962379