RFR: 8319813: Remove upper limit on number of compiler phases in phasetype.hpp

[Emanuel Peter]

On Mon, 20 Nov 2023 09:04:27 GMT, Daniel Lundén <duke at openjdk.org> wrote:

> This changeset removes the implicit upper limit on the number of compiler phases in `phasetype.hpp`. The limit was due to the 64-bit mask used in `Compile::should_print_phase`, causing the `assert(cpt < 64, "out of bounds");` in `phasetype.hpp` to trigger when increasing the number of phases to more than 64.
> 
> Changes:
> - Replace the 64-bit mask with a bit map (`utilities/bitMap.hpp`).
> - Clean up the `PhaseNameValidator` interface by allocating the mask internally.
> - Move the check for whether a mask is non-zero ("is set") into `PhaseNameValidator`.
> - Add a method `should_print_phase` to `DirectiveSet`, simplifying the `if`-condition in `Compile::should_print_phase`.
> 
> ### Testing
> Platforms: windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64.
> - `tier1`
> - HotSpot parts of `tier2` and `tier3`

src/hotspot/share/opto/phasetype.hpp line 198:

> 196:   }
> 197: 
> 198:   const BitMap& mask() const { return _mask; }

You could additionally assert `is_valid` before returning the mask, just to ensure it is never called when invalid.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16729#discussion_r1399206379