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Adds `branch_fold` as a new post-lowering optimizer pass. Simplifies `BranchIf` terminators when the condition variable is defined by a known comparison (Eqz, Ne(x,0), Eq(x,0)), replacing the condition with its operand directly and swapping targets where needed. Dead defining instructions are cleaned up by the subsequent `dead_instrs` pass. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This was referenced Mar 27, 2026
arnoox
commented
Mar 27, 2026
arnoox
commented
Mar 27, 2026
arnoox
commented
Mar 27, 2026
- Remove local `build_global_const_map` from branch_fold — utils already provides an identical implementation; import it instead - Move `is_zero` helper to utils so it can be shared by other passes - Compute both `global_uses` and `global_consts` in `eliminate` and pass both into `fold_one`, making the two maps symmetric at the call site - Drop the per-block `local_consts` clone — `build_global_const_map` already captures all Const-defined variables across the function in SSA form, so the block-level augmentation was redundant Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
branch_foldas a new post-lowering optimizer passBranchIfterminators when the condition is defined byEqz,Ne(x,0), orEq(x,0)— replaces the condition variable with its operand and swaps targets where neededdead_instrspassPipeline position
Test plan
cargo test -p herkos-core --lib— 197 tests pass (5 new branch_fold tests)cargo clippy— cleancargo fmt --checkStack
This is PR F1 of 4 in the optimizer split. Stacked on
main.branch_foldlocal_csegvnlicm🤖 Generated with Claude Code