RFR: 8275202: C2: optimize out more redundant conditions [v3]

[Roland Westrelin]

On Mon, 9 Jun 2025 07:35:10 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> I tested this changeset applied on top of jdk-25+26 (Oracle CI tier1-5) and found the following issues (besides the trivial `NULL` occurrence reported above):

I pushed new commits that should address those failures. I added a test case for that one (a tricky issue):

>     * `assert(c->_idx >= _unique || _type_table->find_type_between(c, c, _phase->C->root()) != Type::TOP) failed: for If we don't follow dead projections`  in multiple tests, e.g. `compiler/predicates/TestHoistedPredicateForNonRangeCheck.java` and 	`compiler/predicates/assertion/TestOpaqueInitializedAssertionPredicateNode.java`.

New commits also include some tweaks and cleanup.

@robcasloz would you mind running tests again?

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PR Comment: https://git.openjdk.org/jdk/pull/14586#issuecomment-3027043159