Validates Phase 75-3 optimization on FAST PGO baseline binary:
4-Point Matrix Results (FAST PGO, Mixed SSOT):
- Point A (C5=0, C6=0): 53.81 M ops/s [Baseline]
- Point B (C5=1, C6=0): 53.03 M ops/s (-1.45% regression)
- Point C (C5=0, C6=1): 54.17 M ops/s (+0.67% gain)
- Point D (C5=1, C6=1): 55.51 M ops/s (+3.16% cumulative) [TARGET]
Decision: ✅ GO (+3.16% exceeds +3.0% ideal threshold)
Comparison to Standard (75-3):
- Standard Point A: 57.96 M ops/s → PGO: 53.81 M ops/s (-7.16%)
- Standard Point D: 61.10 M ops/s → PGO: 55.51 M ops/s (-9.15%)
- Standard gain: +5.41% → PGO gain: +3.16% (-2.25pp)
Critical Finding:
- PGO captures 58.4% of Standard's gain (3.16% vs 5.41%)
- 14% regression vs Phase 69 baseline (62.63 M ops/s)
- Root cause: Likely stale PGO profile (trained pre-Phase 69+)
Immediate Action Required:
- Promote C5+C6 to SSOT (confirmed on FAST PGO)
- HIGH PRIORITY: Regenerate PGO profile with C5=1, C6=1 config
- Investigate Phase 69 baseline regression (Phase 75-5)
Artifacts: docs/analysis/PHASE75_4_FAST_PGO_REBASE_RESULTS.md
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>