RFR: 8365071: ARM32: JFR intrinsic jvm_commit triggers C2 regalloc assert

[Sergey Bylokhov]

On Tue, 19 Aug 2025 04:38:54 GMT, Boris Ulasevich <bulasevich at openjdk.org> wrote:

>> On 32-bit ARM, the jvm_commit JFR intrinsic builder feeds null (RegP) into a TypeLong Phi, causing mixed long/pointer register sizing and triggering the C2 register allocator assert(_num_regs == reg || !_num_regs).
>> 
>> The fix is trivial: use an appropriate ConL constant instead. This has no effect on 64-bit systems (the generated assembly is identical) but resolves a JFR issue on 32-bit systems.
>
> Thanks!

Hi @bulasevich, do you plan to backport this patch to jdk21u-dev? Seems it is also affected, I have encounter the same crash.

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PR Comment: https://git.openjdk.org/jdk/pull/26684#issuecomment-3565352748