nx_f64_adversary.nx

nx_f64_adversary.nx -- T12 class: hardware f64 (IEEE-754 binary64) codegen. Before 2026-07-16 nx_cc PARSED f64 but SILENTLY MISCOMPILED f64 arithmetic to single precision (the parser forced every fp binop result to TY_F32, so the emitter used movss/divss -> low-32-bit reinterpret -> garbage). Fixed by fp_result_type (TY_F64 propagation) + x86ctx_emit_f64 (movsd/addsd/subsd/ mulsd/divsd/sqrtsd/cvtsi2sd/cvttsd2si) + the __f64_from_i64/__f64_to_i64/ __f64_sqrt intrinsics. Self-checking (exit 0 = all f64 ops bit-correct); every constant is a known IEEE-754 value truncated to a fixed integer scale, so a single-precision regression (or a wrong conversion) changes the digits. license_tier: ORIGINAL No hw writes (Rule 26).