RFR: 8329982: compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java failed assert(oopDesc::is_oop_or_null(val)) failed: bad oop found [v2]

[Doug Simon]

On Thu, 2 May 2024 01:06:48 GMT, Dean Long <dlong at openjdk.org> wrote:

> Wouldn't it be useful for the JVMCI implementation to provide the nmethod entry barrier code? I could be wrong, but I think all the JIT compiler needs to know is how big it is, so it can reserve the space (NOPs would do), then when the code is installed as an nmethod, memcpy it over (if it's static), or use the MacroAssembler if it's not.

That's an interesting idea and would be great if possible. However, given that Graal [puts the slow path out-of-line](https://github.com/oracle/graal/blob/c0b79318e2158a22bec5a9a991ee6ee226de6492/compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/hotspot/amd64/AMD64HotSpotBackend.java#L195), we'd be stuck with the problem of patching in the jump target. Also, JVMCI would have to conservatively emit a long-form jump instruction to the slow path.

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PR Comment: https://git.openjdk.org/jdk/pull/19035#issuecomment-2090014082