RFR: 8259316: [REDO] C1/C2 compiler support for blackholes

[Doug Simon]

On Mon, 11 Jan 2021 10:18:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> This reworks the compiler support for blackholes. The key difference against the last version (#1203) is that blackholes are only acceptable as empty static methods, which both simplifies the implementation and eliminates a few compatibility questions.

src/hotspot/share/ci/ciMethod.cpp line 160:

> 158: 
> 159:   if (CompilerOracle::should_blackhole(h_m)) {
> 160:     h_m->set_intrinsic_id(vmIntrinsics::_blackhole);

Wouldn't it be better to do this in `Method::init_intrinsic_id` so that JVMCI will also see the method as an intrinsic? Either that or a similar bit of logic should be added to `JVMCIRuntime::compile_method`.

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PR: https://git.openjdk.java.net/jdk/pull/2024