On Sun, 1 Jun 2025 13:07:50 GMT, Erik Gahlin <egah...@openjdk.org> wrote:
>> src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line >> 256: >> >>> 254: // } >>> 255: getEventConfiguration(codeBuilder); >>> 256: codeBuilder.aload(0); >> >> Can issue a dup() here if you want to avoid the second aload(0). > > I don't think it will work because the result of the first getField > (startTime) will be on the stack, when we issue the next getField (duration). No big deal, we can look into the details later. >> src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line >> 261: >> >>> 259: getfield(codeBuilder, eventClassDesc, >>> ImplicitFields.FIELD_DURATION); >>> 260: Bytecode.invokevirtual(codeBuilder, >>> TYPE_EVENT_CONFIGURATION, METHOD_THROTTLE); >>> 261: int result = codeBuilder.allocateLocal(TypeKind.LONG); >> >> Do we really need to store the result in a local? Can't we just dup it on >> the expression stack and store it directly into the field after another >> aload, or dup? Perhaps dup twice to then issue the mask operation? > > We could do an aload(0) at the beginning, before > getEventConfiguration(codeBuilder), to have "this" for putfield(duration) > later, but then we would need to do a getfield(this.duration) to have it on > the stack for the mask. > > We can't do a dup() on duration because we need "this" on the stack to store > it in this.duration. I thought using a local variable would be faster than > accessing this.duration. It also reduces the chance of the value being > changed by another thread. No big deal, we can look into this later if the need arises. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2120675164 PR Review Comment: https://git.openjdk.org/jdk/pull/25559#discussion_r2120676832
