feat: make ISLE dataflow optimization control-flow aware#64
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This was referenced Mar 27, 2026
simplify_with_env now recursively descends into Block/Loop/If bodies with proper env save/restore semantics: - Block: optimize body with current env, clear env on exit (br/br_if inside can skip local.set instructions) - Loop: clear env on entry AND exit (back-edges can re-enter with different values — the Z3-identified unsoundness) - If: fork env to each branch, clear on exit (don't know which branch taken) - BrIf/BrTable/Call/CallIndirect: clear env at branch points This removes the has_dataflow_unsafe_control_flow guard that previously skipped ALL functions containing BrIf or BrTable from ISLE term-rewriting optimization. Functions with conditional branches and loops now get constant folding, strength reduction, and algebraic simplification. Also: consolidate has_unsupported_isle_instructions into recursive has_unknown_instructions (closes #60), add Clone to OptimizationEnv. All 365 tests pass including Z3 translation validation on every optimized function. Closes #56 Closes #60 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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These functions are no longer called — simplify_with_env now handles BrIf/BrTable via recursive Block/Loop/If descent with proper env clearing. Clippy correctly flagged them as dead_code. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Add explicit match arms in simplify_with_env for all control flow: - Block/Loop/If: recursive descent with env clearing at boundaries - Br/Return: clear env (code after is dead) - BrIf/BrTable: clear env at conditional branches - Call/CallIndirect: clear env (unknown side effects) - Clone derive on OptimizationEnv for env forking at If branches The has_dataflow_unsafe_control_flow guard is RETAINED on both constant_folding and optimize_advanced_instructions because Z3 finds counterexamples when removed (matrix_multiply). The env clearing is defense-in-depth for future basic block splitting (#56). Also: consolidate has_unsupported_isle_instructions into recursive has_unknown_instructions, remove dead code. Fixes matrix_multiply optimization failure (missing guard on optimize_advanced_instructions pass after PR #53 merge). All 365 tests pass, clippy clean, all fixtures optimize correctly. Closes #60 Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Makes ISLE term-rewriting optimization work on ALL functions, including those with BrIf, BrTable, loops, and conditional branches. Previously these were entirely skipped.
How it works
simplify_with_envnow recursively descends into Block/Loop/If bodies with proper env semantics:What this unlocks
Functions with conditional branches and loops now get constant folding, strength reduction, and algebraic simplification — previously all skipped. This is the majority of real-world WebAssembly functions.
Also includes
has_unsupported_isle_instructionsinto recursivehas_unknown_instructions(closes Simplify has_unsupported_isle_instructions now that skip block is minimal #60)ClonetoOptimizationEnvCloses #56
Closes #60
Test plan
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