v0.2.0

[0.2.0] - 2026-06-03

Major release: a target-agnostic native SSA substrate for modern lifters,
new construction/editing infrastructure, and a broad performance/memory pass.
A few IR enum shapes changed (see Changed).

Added

• Native SSA substrate: target-independent pointer sizes & endianness;
  first-class SIMD/vector operations with target-independent lane/vector-type
  semantics; native atomics (exchange, lock-RMW, compare-exchange); native
  opaque operations with machine-state clobbers; multi-output SSA definitions;
  boolean ops and native condition helpers; native flag semantics; and implicit
  wide (low/high, quotient/remainder) arithmetic.
• Memory effect summaries, exception/interrupt support, and native operation
  classes plus target-generic feature tokens.
• Fluent SSA builder (ir::function::builder) and a checked, verifier-preserving
  SSA editor (ir::function::editor); all built-in passes migrated onto the
  checked mutation APIs.
• Recommended normalization-pipeline API, pass bisection/debug hooks, and
  structured verifier diagnostics.
• Expanded Target trait (vector descriptors, pointer sizes, endianness),
  MockTarget, and a much larger test suite (builder, scheduling, verifier,
  pipeline, and canonicalization coverage).
• Allocation-free helpers: SsaOp::{uses_var, for_each_successor, has_successor},
  SsaInstruction::{uses_var, for_each_variable}, SsaBlock::for_each_successor,
  SymbolicExpr::for_each_variable, SsaFunction::compute_predecessors,
  BitSet::is_full, EventLog::into_events, EventListener::is_enabled.

Changed (breaking)

• SsaOp::NativeOpaque is now a tuple variant wrapping a boxed payload
  (NativeOpaque(Box<NativeOpaqueData>)) instead of an inline struct variant.
• ConstValue heap-bearing arms are now boxed: Vector(Box<[ConstValue<T>]>),
  DecryptedString(Box<str>), DecryptedArray(Box<DecryptedArrayData<T>>).
• SsaOp and ConstValue gained many new variants for the native substrate;
  exhaustive downstream matches must handle them.

Performance & memory

• Shrunk core IR types ~3–4×: SsaOp 168→40 B, SsaInstruction 176→48 B,
  Option<SsaVarId> 16→4 B (niche-encoded SsaVarId), ConstValue 40→24 B,
  PhiOperand 16→8 B; guarded by a size_of regression test.
• Removed hot-loop allocations (uses()/successors() purge, word-skipping
  BitSet iterator, DFS/postorder scratch reuse, cached solver exit set).
• DefUseIndex uses dense Vec-indexed storage instead of BTreeMap.
• De-quadratized DCE, GVN removal, jump-threading safety check, LICM invariant
  detection, predicate branch evaluation, trivial-phi predecessor build, and
  block-merge redirection; dataflow solver uses an RPO-priority worklist.
• DirectedGraph stores neighbor ids inline, IndexedGraph dedups edges in
  O(1), and cycle detection is iterative (stack-safe on deep graphs).
• Scheduler dirty-set membership is O(1); logging allocates nothing under
  NullListener.