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

[Boris Ulasevich]

On Fri, 8 Aug 2025 01:54:46 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!

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PR Comment: https://git.openjdk.org/jdk/pull/26684#issuecomment-3199179245