RFR: 8293999: [JVMCI] need support for aligned constants in generated code larger than 8 bytes

[Dean Long]

On Mon, 24 Oct 2022 08:36:45 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> 8293999: [JVMCI] need support for aligned constants in generated code larger than 8 bytes
>
> src/hotspot/share/asm/codeBuffer.hpp line 755:
> 
>> 753:     if (EnableJVMCI) {
>> 754:       // Graal vectorization requires larger aligned constants
>> 755:       return 64;
> 
> This means all Graal installed code will pay a penalty even though most installed code does not include constants that need such large alignment. It would be preferable to allow a compiler to specify the alignment requirement per nmethod.

I agree. The alignment should probably be a field in CodeBuffer with a default value of 8.

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PR: https://git.openjdk.org/jdk/pull/10392