P3 phase merged at f3ebaba. Update audit-findings.md status fields and
append the P3 progress section to audit-report-2026-04-29.md, including
the new PPCBUG-700 discovery (VMX128 register accessor canary-compliance).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Independent review of P3 batch 2 (52ece4b) found that all three VMX128
register accessors disagreed with canary's FormatVX128/VX128_R bitfield
struct (`xenia-canary/src/xenia/cpu/ppc/ppc_decode_data.h:484-663`). The
audit at line 2958 had marked these "confirmed-clean" but had miscounted
LSB-first bitfield offsets.
Canary's actual layout (LSB-first, GCC/Clang/MSVC on x86):
VA128 = VA128l(5) | VA128h(1)<<5 | VA128H(1)<<6
= PPC[11:15] | PPC[26]<<5 | PPC[21]<<6 (7-bit selector, 3 fields)
VB128 = VB128l(5) | VB128h(2)<<5
= PPC[16:20] | PPC[30:31]<<5 (7-bit selector, 2 fields)
VD128 = VD128l(5) | VD128h(2)<<5
= PPC[6:10] | PPC[28:29]<<5 (7-bit selector, 2 fields)
VX128_R Rc = PPC[25] (host bit 6) not PPC[27] as prior fix had
The buggy convention was internally consistent with hand-crafted test
fixtures (which set bits 29/21/22 to encode the high registers, matching
the buggy accessor). Real Xbox 360 game code follows canary's convention,
so any production VMX128 instruction with VR >= 32 was silently mis-decoded
— but no unit test exercised that path until the va128 fix in 52ece4b
exposed the inconsistency.
Changes:
- decoder.rs: rewrite va128/vb128/vd128/vx128r_rc_bit to canary positions.
Drop the speculative `key4_dt` dot-form dispatch in decode_op6 — canary
has no separate dot-form opcodes for VX128_R compute ops; Rc is a
runtime modifier read by the interpreter via vx128r_rc_bit().
- decoder.rs tests: rewrite vmx128_test_word helper for canary layout;
rename/re-encode vmx128_vd128_*, vmx128_va128_*, vmx128_vb128_* tests.
- interpreter.rs: update encode_vpkd3d128 test helper to encode VD via
canary's VD128h field; tests now pass vd=96 explicitly.
- tests/disasm_goldens.rs: replace the vrlimi128/vsrw128/vpermwi128/
vperm128 hand-encoded raws with canary-compliant encodings; introduce
a shared `encode_vx128` helper.
- tests/golden/vmx128_registers.json: re-encode 9 entries (vperm128,
vsrw128 ×2, vpermwi128, vrlimi128 ×2, vmaddfp128, vmaddcfp128,
vnmsubfp128) to canary-compliant raws preserving the same expected
operand strings.
- audit-findings.md: new PPCBUG-700 entry documenting the discovery and
invalidating the audit's "confirmed-clean" assessment.
Affects all VMX128 binary ops (vaddfp128, vsubfp128, vmulfp128, vand128,
vor128, vxor128, vnor128, vandc128, vsel128, vslo128, vsro128, vperm128,
vsrw128, vmaddfp128, vmaddcfp128, vnmsubfp128, vpkd3d128, vpkshss128,
vpkshus128, vpkswss128, vpkswus128, vpkuhum128, vpkuhus128, vpkuwum128,
vpkuwus128, vmsum3fp128, vmsum4fp128, vrlimi128, vpermwi128 — 30+
opcodes), plus VX128_R compare dot-forms.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
