RFR: 8361892: AArch64: Incorrect matching rule leading to improper oop instruction encoding [v2]

[Aleksey Shipilev]

On Mon, 14 Jul 2025 11:19:07 GMT, Andrew Dinn <adinn at openjdk.org> wrote:

> One other thing. I believe that the only code that creates a RawPtr ConP for the card table base is in the shared C2 card table barrier set assembler. Now that we have moved to late barrier insertion for G1 (along with Shenandoah and Z)

Shenandoah still does not do late barrier expansion. But it also does not emit card table bases as constants, it loads card table bases from TLS. G1 would do this with throughput GC barriers soon too, AFAICS. I think Shenandoah also encodes some "unallocated" `ConP` for the similar biased-base trick, e.g. for collection set bitmap, but none of those ever pretend to be oops.

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PR Comment: https://git.openjdk.org/jdk/pull/26249#issuecomment-3070267666