[cataggar]

Summary

Implements single-constant algebraic identities, zero-comparison eqz lowering, comparison inversion, boolean/branch condition normalizations, multiplicative identities, power-of-two strength reductions, and additive/bitwise constant reassociation across both Wasm optimizers:

• MIR Intrafunction Optimizer (src/codegen/wasm/Optimize.zig) and Core Wasm Module Optimizer (src/link/Wasm/component/Optimizer.zig):
  • Additive, bitwise, and shift identities: x + 0, x - 0, x | 0, x ^ 0, x & -1, shifts/rotations by masked 0 ((c & 31) == 0 / (c & 63) == 0), and commutative left-identities (0 + x, 0 | x, 0 ^ x, -1 & x) on single 0-pop pure instructions.
  • Zero comparison & boolean/branch normalization:
    • x == 0 $\rightarrow$ i32.eqz / i64.eqz (saving 2 bytes per zero test).
    • <cmp>; i32.eqz $\rightarrow$ inverted comparison for all 10 i32 comparisons, all 10 i64 comparisons, and f32/f64 eq <-> ne.
    • Redundant boolean normalizations after boolean producers (<cmp>; != 0, <cmp>; == 1, <cmp>; & 1, <cmp>; ^ 1, <cmp>; != 1, <cmp>; i32.eqz; i32.eqz).
    • Condition normalizations before br_if, select, and if (<x>; i32.const 0; i32.ne and <x>; i32.eqz; i32.eqz stripped).
  • Multiplicative identities & power-of-two strength reductions:
    • x * 1, x /_s 1, x /_u 1 $\rightarrow$ x (plus commutative 1 * x).
    • x * 2^k ( \ge 1$) $\rightarrow$ x << k (plus commutative 2^k * x).
    • x /_u 2^k ( \ge 1$) $\rightarrow$ x >>_u k.
    • x %_u 2^k ( \ge 0$) $\rightarrow$ x & (2^k - 1).
    • Non-trapping two-constant div_s, div_u, rem_s, rem_u constant folding.
  • Constant reassociation:
    • (x +- c1) +- c2 $\rightarrow$ x + (d1 +% d2) (or x when 0), allowing mixed-sign constant chains like (x + 16) - 4 to fold directly into MemArg.offset in the same pass.
    • Associative bitwise constant reassociation for &, |, and ^.

Closes #113