eb7c6f98cd
Native fmadds/fmsubs/fnmadds/fnmsubs + double siblings via hardware FMA (vfmadd213sd/vfmsub213sd — single rounding, matching the interpreter's correctly-rounded f64::mul_add; negated forms flip the result sign with xorpd, and NaN — which the interpreter preserves unnegated — is caught by the finite guard → deopt, so unconditional negate is exact on the fast path). Gated on a runtime cpuid FMA3 check (emit::host_has_fma, cached OnceLock); on a non-FMA host these arms fall back to the interpreter's software FMA — byte-identical, so goldens hold on any host (NEVER emit mulsd+addsd, which double-rounds). fp_arith_matches extended to the madd family (guarded on host FMA3). All 6-config GOLDEN n200m BYTE-IDENTICAL; 24 xenia-jit tests green. MEASURED (2B-instr run through the video, --gpu-inline, best-of-3) — CLEAN 3-way: interp 72.6s (27.5 MIPS) region JIT (pre-FP) 27.3s (73.2 MIPS) = 2.66x over interp region JIT + native FP 23.3s (85.8 MIPS) = 3.12x over interp So native FP's OWN contribution is ~1.17x (+17%) on top of the region JIT — it removed 62% of all interpreter fallbacks (306.6M→117.3M, the FP-arith share) but that translates to only ~17% wall-time here because the region JIT already made non-FP code fast and the --gpu-inline drain + plumbing dominate the remainder. This matches the conservative ~1.3-1.5x plan estimate (region JIT is the bigger CPU lever on the video; FP is a solid, deterministic increment and a multiplier for a future multi-core mode). Video still ~7x from real-time → multi-core next.