ipa-optimizer

name	ipa-optimizer
description	Implement issue

IPA Optimizer

Use this skill to execute issue #87 with analysis-first, regression-safe steps.

Workflow

1. Build CallGraph in llvm-analysis (direct/indirect/external edges + SCCs).
2. Add an IPCP module pass with at least one constant-argument specialization.
3. Add dead-argument elimination module pass and tests.
4. Integrate IPA passes into O3 pipeline.
5. Validate measurable O3 improvement on a multi-function benchmark fixture.

Step 1: CallGraph Core

• Add a module-level call graph data type.
• Preserve edge kind (direct, indirect, external) for downstream decisions.
• Provide caller/callee queries and SCC traversal API.

Step 2: IPCP

• Detect callsites with stable constant arguments.
• Clone/specialize callee where profitable.
• Re-run intra-procedural const propagation on specialized clone.
• Keep linkage and function-id bookkeeping correct.

Step 3: Dead Argument Elimination

• Remove parameters unused by callee and all callsites.
• Rewrite function signature and update all affected call instructions.
• Add a targeted regression test.

Step 4: O3 Integration

• Integrate new module passes into O3 only, unless data supports earlier insertion.
• Ensure fixed-point loop in pass manager converges without oscillation.

Step 5: Validation

Run at minimum:

cargo +stable test -p llvm-analysis
cargo +stable test -p llvm-transforms
cargo +stable test

If benchmark environment is constrained, capture instruction-count deltas as deterministic proxy.

Step 6: Review + Full Test

• Review implementation PR for semantic correctness, pass-pipeline safety, and missing tests.
• Run targeted checks and full suite (cargo +stable test) unless blocked.

Step 7: Issue+Fix Loop (Same PR)

• If concrete problems are found, open GitHub issue(s) for traceability.
• Fix them in the same PR branch and push follow-up commits.

Step 8: Post Review Summary

• Post PR review feedback (gh pr review --comment or gh pr comment) summarizing findings and fixes.
• Include links to issues opened during review.

Resources

• Use references/issue-87-plan.md for acceptance checklist.
• Use scripts/callgraph_audit.sh to inspect call instructions and edge coverage quickly.