8334647: C2: CastII added by PhaseIdealLoop::add_template_assertion_predicate() should have control

[rwestrel]

PhaseIdealLoop::add_template_assertion_predicate() creates a new CastII but doesn't set its control. I think it's good practice to always set the control of a CastII when it narrows the type of its input (it has to be control dependent on some condition that makes the narrowing possible). This is also motivated by https://bugs.openjdk.org/browse/JDK-8275202 where a node that becomes top is used as an indication that control flow where the node changes type can constant fold. This only works if control is set correctly.

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Issue

• JDK-8334647: C2: CastII added by PhaseIdealLoop::add_template_assertion_predicate() should have control (Bug - P4)

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

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