perf(core/vm): hoist jumptable nil-check out of the interpreter loop #32068

[gzliudan]

Proposed changes

Refactor the EVM interpreter to clarify and optimize jump table access. This improves code readability and may slightly enhance performance. No logic is changed.

Ref: ethereum#32068

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• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Changes that don't change source code or tests
• docs: Documentation only changes
• feat: A new feature
• fix: A bug fix
• perf: A code change that improves performance
• refactor: A code change that neither fixes a bug nor adds a feature
• revert: Revert something
• style: Changes that do not affect the meaning of the code
• test: Adding missing tests or correcting existing tests

Impacted Components

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• Consensus
• Account
• Network
• Geth
• Smart Contract
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Checklist

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• This PR has sufficient test coverage (unit/integration test) OR I have provided reason in the PR description for not having test coverage
• Tested on a private network from the genesis block and monitored the chain operating correctly for multiple epochs.
• Provide an end-to-end test plan in the PR description on how to manually test it on the devnet/testnet.
• Tested the backwards compatibility.
• Tested with XDC nodes running this version co-exist with those running the previous version.
• Relevant documentation has been updated as part of this PR
• N/A

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[Copilot]

Pull request overview

Optimizes the EVM interpreter’s hot loop in core/vm by caching the jump table pointer locally and forcing the jump table nil-check to occur once before entering the opcode dispatch loop, aiming for slightly improved performance and clearer jump table access.

Changes:

• Cache evm.table into a local jumpTable variable used for opcode dispatch.
• Hoist the jump table nil-check out of the interpreter loop via a single pre-loop array access.
• Replace per-iteration evm.table[op] access with jumpTable[op].

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