RFR: 8304930: Enable Link Time Optimization as an option for Visual C++

[Julian Waters]

On Sun, 2 Apr 2023 07:00:51 GMT, Julian Waters <jwaters at openjdk.org> wrote:

> Currently, Link Time Optimization is only available for Java Virtual Machines compiled with gcc. Since the Java VM is the most performance critical part of the Java Platform for obvious reasons, it follows that optimized executables produced for Windows (as Visual C++ is currently the only compiler available for Windows as [JDK-8288293](https://bugs.openjdk.org/browse/JDK-8288293) is still under heavy development) would grant a significant performance boost for Java on Windows as a whole. Flags used for link time optimizations are set to make compiling with it enabled as fast as possible, to avoid the pitfall of very long compile times
> 
> Depends on [JDK-8304893](https://bugs.openjdk.org/browse/JDK-8304893) being integrated first, to prove that link time optimization is viable as an option

Ah, I was thinking that the tests could be used to verify the build times of the new option, I guess it isn't needed then. It's still the same default of false, it's just that the option now has a new implementation for a new compiler

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PR Comment: https://git.openjdk.org/jdk/pull/13280#issuecomment-1508705873