771bf6b0d1
Added verify_exit_phi_no_collision() to contract_checks.rs for early detection of ValueId collisions between exit PHIs and other instructions. Problem detected: - If exit_phi_builder uses builder.value_gen.next() (module-level) instead of func.next_value_id() (function-level), ValueIds can collide: Example: - bb0: %1 = const 0 (counter init) - bb3: %1 = phi ... (exit PHI - collision!) Previous behavior: - Error only detected at LLVM backend runtime - Cryptic error: "Cannot overwrite PHI dst=1" New behavior: - Panic at Rust compile time (debug build) - Clear error message with fix suggestion: "Exit PHI dst %1 collides with instruction in block 0 Fix: Use func.next_value_id() in exit_phi_builder.rs" Benefits: - 🔥 Fail-Fast: Catch errors during Rust compilation, not LLVM execution - 📋 Clear messages: Exact collision point + fix suggestion - 🧪 Testable: verify_exit_phi_no_collision() can be unit tested 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Investigations Folder
This folder contains investigation notes and analysis for debugging sessions.
Active Investigations
Phase 131-12: LLVM Wrong Result (Case C)
Status: ✅ Root cause identified Problem: LLVM backend returns wrong results for loop exit values Root Cause: vmap object identity mismatch between Pass A and Pass C
Key Documents:
- phase131-12-case-c-llvm-wrong-result.md - Initial investigation scope
- phase131-12-p1-vmap-identity-analysis.md - Detailed trace analysis
- phase131-12-p1-trace-summary.md - Executive summary with fix recommendations
Quick Summary:
- Bug: Pass A deletes
_current_vmapbefore Pass C runs - Impact: Terminators use wrong vmap object, missing all Pass A writes
- Fix: Store vmap_cur in deferred_terminators tuple (Option 3)
Next Steps:
- Implement Option 3 fix in block_lower.py
- Add Fail-Fast check in instruction_lower.py
- Verify with NYASH_LLVM_VMAP_TRACE=1
- Run full test suite
Trace Environment Variables
Phase 131-12-P1 Traces
NYASH_LLVM_VMAP_TRACE=1 # Object identity and vmap keys tracing
NYASH_LLVM_USE_HARNESS=1 # Enable llvmlite harness
NYASH_LLVM_DUMP_IR=<path> # Save LLVM IR to file
Investigation Workflow
- Scope - Define problem and test case (phase131-12-case-c-*.md)
- Trace - Add instrumentation and collect data (phase131-12-p1-vmap-identity-*.md)
- Analysis - Identify root cause with evidence (phase131-12-p1-trace-summary.md)
- Fix - Implement solution with validation
- Document - Update investigation notes with results
Archive
Completed investigations are kept for reference and pattern recognition.