RFR: 8286660: codestrings gtest fails on AArch64: "udf" in padding

[Aleksey Shipilev]

On Fri, 13 May 2022 11:04:06 GMT, Stuart Monteith <smonteith at openjdk.org> wrote:

> That's interesting. While the permanently undefined instruction, and immediate, is defined, I suppose it could be treated as an undefined instruction, and ignored. We don't actually emit or even define this instruction in the aarch64 assembly, so it can be safely ignored. LGTM.

Yeah. I think that's just the zeroed memory at the end of the code buffer that gets disassembled into `udf`. So maybe I should just match `udf #0` without matching other masks. We could probably figure out why that tail is not `nop`-ped fully, but it does not seem worth investing into.

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PR: https://git.openjdk.java.net/jdk/pull/8695