feat(jit): SSA optimization pipeline with CSE/Load CSE - REVIEW NEEDED

[bardo84]

Summary

Adds SSA-based optimization passes to the Turbine JIT compiler, achieving 7.3x speedup on loop-heavy benchmarks.

⚠️ Review Required

This is an experimental implementation that requires review by founding authors before production use. Key areas needing attention:

• SSA IR correctness (ssa.rs, ssa_builder.rs)
• Optimization pass safety (ssa_opt.rs)
• Performance variance investigation (see benchmark notes)
• size level regression (slower than none)

Suggested Review Order

1. Start here: SSA_IR_DEEP_DIVE.md (architecture overview)
2. Core IR: ssa.rs (data structures, 500 lines)
3. Optimizations: ssa_opt.rs - focus on:
   • optimize() function (lines 23-52)
   • cse() (lines 347-395)
   • load_cse() (lines 404-450)
4. Integration: lib.rs changes (146 lines modified)
5. Skip for now: dominators.rs, loop_analysis.rs (standard algorithms)

Benchmark Results (4B iterations, median of 7 runs)

CLI Optimization Levels

--jit-opt-level	SSA Passes	Time	vs none
none	—	3.89s	1x
size	simplify + DCE	11.18s	0.35x (slower)
speed	simplify + DCE + CSE + Load CSE	0.53s	7.3x
aggressive	+ LICM	3.36s	1.2x

Individual Pass Analysis (via RUNMAT_SSA_PASSES)

Mask	Passes Enabled	Time	Notes
0	none	3.89s	Baseline
1	SIMPLIFY only	10.71s	Slower than none
2	DCE only	10.97s	Slower than none
3	SIMPLIFY + DCE	11.18s	Same as size
12	CSE + LOAD_CSE	5.16s	1.3x faster
14	DCE + CSE + LOAD_CSE	0.45s	8.6x faster
15	All except LICM	0.47s	8.3x faster

Key Insight

CSE + Load CSE are the critical optimizations. The combination of all passes (simplify → DCE → CSE → Load CSE → DCE) produces the best results due to pass synergy.

New Optimizations

1. VarPtr CSE - Eliminates redundant pointer computations
2. Load CSE - Eliminates redundant loads within basic blocks (with store tracking)

Testing

cargo test -p runmat-turbine  # 104 tests pass
RUNMAT_SSA_PASSES=12 runmat script.m  # Fine-grained pass control

[vercel]

@bardo84 is attempting to deploy a commit to the Dystr Team on Vercel.

A member of the Team first needs to authorize it.