f6a444b9d1
Phase 5 batch 1 (5a): round-to-int correctness. PPCBUG-221+227 (coupled): round_to_i64 NearestEven tie-breaking used `(diff - 0.5).abs() < f64::EPSILON` to detect half-integers, but for |v| > 2^52 every f64 value is an exact integer (v.trunc() == v), giving diff == 0. The buggy check fell through to v.round() (round-half-away- from-zero), giving wrong results for large odd half-integers. Replaced with a fractional-part-only check that's exact for |v| <= 2^52 and degenerates to truncation above. PPCBUG-432: vrfin/vrfin128 used Rust's `f32::round()` which is round- half-away-from-zero. ISA requires round-to-nearest-even (banker's rounding). Implemented inline. PPCBUG-201 (FPSCR.RN for double arithmetic) deferred — requires MXCSR-set/restore wrappers around 10+ FPU arms; will land in a focused sub-batch after the remaining 5a-5f fixes. Tests: - round_to_i64_nearest_even_on_tie: extended with 0.5, 1.5, -0.5, -1.5. - round_to_i64_non_tie_cases: 0.4/0.6 (non-tie sanity). - round_to_i32_nearest_even_on_tie: PPCBUG-227 coverage. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>