RFR: 8307312: Replace "int which" with "int cp_index" in constantPool

[Ioi Lam]

On Tue, 25 Jul 2023 20:20:33 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

> Many accessors in the constant pool take an argument "int which" that is meant to represent an ambiguous index. Despite this, several methods in the API use "int which" when the argument is exclusively a constant pool index. This patch aims to rename all of these instances to "int cp_index" in order to be more clear and to distinguish methods that take constant pool indices and methods that use derived indices.
> 
> The callers have been updated to use more clear naming as well. Verified with tier 1-5 tests.

Marked as reviewed by iklam (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/15027#pullrequestreview-1553948524