RFR: 8313554: Fix -Wconversion warnings for ResolvedFieldEntry

[Dean Long]

On Wed, 2 Aug 2023 19:15:24 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

> The recent change in [JDK-8301996](https://bugs.openjdk.org/browse/JDK-8301996) added more -Wconversion warnings that are addressed in this patch. The aforementioned change has overlooked inconsistencies with the types used by `ResolvedFieldEntry` and the method `fill_in()`. Verified with tier 1-4 tests.

src/hotspot/share/oops/resolvedFieldEntry.hpp line 106:

> 104:   void set_flags(bool is_final, bool is_volatile) {
> 105:     int new_flags = (is_final << is_final_shift) | static_cast<int>(is_volatile);
> 106:     _flags = (u1)new_flags;

Why isn't this using checked_cast?

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PR Review Comment: https://git.openjdk.org/jdk/pull/15126#discussion_r1282875385