8257221: C2: RegMask::is_bound_set split set handling broken since JDK-8221404

[cl4es]

This patch adds more tests for RegMask::is_bound* operations, and fixes a bug I introduced in JDK-8221404 where I mixed up the formula for how much we need to shift the "bit" when checking a split set.

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Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
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Testing

	Linux additional	Linux x64	Linux x86	Windows x64	macOS x64
Build	⏳ (5/8 running)	✔️ (2/2 passed)	✔️ (2/2 passed)	⏳ (1/2 running)	✔️ (2/2 passed)
Test (tier1)		⏳ (8/9 running)	⏳ (3/9 running)		⏳ (1/9 running)

Issue

• JDK-8257221: C2: RegMask::is_bound_set split set handling broken since JDK-8221404

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer) ⚠️ Review applies to 2937939
• Nils Eliasson (@neliasso - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1486/head:pull/1486
$ git checkout pull/1486

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[mlbridge]

Webrevs

• 02: Full - Incremental (6980ee0)
• 01: Full - Incremental (2937939)
• 00: Full (3245e38)

[vnkozlov]

okay.

[openjdk]

@cl4es This change now passes all automated pre-integration checks.

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8257221: C2: RegMask::is_bound_set split set handling broken since JDK-8221404

Reviewed-by: kvn, neliasso

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[cl4es]

@vnkozlov - as we discussed I split out the optimizations to a separate RFE, leaving the new tests and the one-liner bug fix for this PR.

[vnkozlov]

Looks good.

[neliasso]

Looks good.

[cl4es]

/integrate

[openjdk]

@cl4es Pushed as commit 9bcd269.

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