LLVM vs stock GCC

[Henri Gomez]

> The core functionality that Henri's test are evaluating are effectively complete. I would speculate that the minor drop in performance is likely the combination of forcing stack pointer alignment to 16-byte boundaries, and using -Os instead of -O3, as opposed to any systemic issue with LLVM.
>
> It would be interesting to find the combination of options that cause xalan, lusearch, and eclipse to fall behind the other OpenJDK variants. If there is an issue with using the LLVM backend, a bug should be filed against it ASAP (of course comparing -Os to -Os or -O3 to -O3, and ensuring all other factors are equal).

I could redo the test of course. Did there is a way to change globally
LLVM CC+C++ flags ?