RFR: 8324433: Introduce a way to determine if an expression is evaluated as a constant by the Jit compiler [v6]

[Roland Westrelin]

On Wed, 24 Jan 2024 18:56:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> > Naive question: the right way to use this would be almost invariably be like this:
> > ```
> > if (isCompileConstant(foo) && fooHasCertainStaticProperties(foo)) {
> >     // fast-path
> > }
> > // slow path
> > ```
> > 
> > 
> >     
> >       
> >     
> > 
> >       
> >     
> > 
> >     
> >   
> > Right?
> 
> Yes, I think so.

But then whatever is in the fast path and `fooHasCertainStaticProperties` are never profiled because never executed by the interpreter or c1. So `fooHasCertainStaticProperties` will likely not be inlined and c2 will do a poor (or rather not as good as you'd like) job of compiling whatever is in the fast path.

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PR Comment: https://git.openjdk.org/jdk/pull/17527#issuecomment-1909531426