feat(asm): add the EVEX floating-point and conversion set

Assisted-by: Qwen 3.8 Max Preview

docs/ARCHITECTURE.md

@@ -213,9 +213,13 @@ three-operand-plus-immediate form (`VSHUFPD`,
 `VPERM2I128`, `VINSERTI128`), the lane-extract form (`VEXTRACTI128`,
 `VEXTRACTF128`, where the YMM source occupies the reg field and the XMM or
 memory destination r/m), the direction-sensitive moves (`VMOVDQU`, `VMOVUPD`,
-`VMOVD`, `VMOVQ`, `VMOVSD`), the floating-point and FMA arithmetic (`VADDPD`,
-`VMULPD`, `VXORPD`, `VUNPCKHPD`, the scalar `VADDSD`/`VMULSD`, `VCVTDQ2PD`,
-`VFMADD231PD`) and the no-operand `VZEROUPPER` — together with `VPERMD` and
+`VMOVD`, `VMOVQ`, `VMOVSD`), the floating-point and FMA arithmetic — the
+packed double operations (`VADDPD`/`VSUBPD`/`VMULPD`/`VDIVPD`/`VMINPD`/
+`VMAXPD`), the unpacks (`VUNPCKHPD`/`VUNPCKLPD`), the scalar SD and SS
+operations, `VMOVDDUP`, `VXORPD`, the width-changing conversions
+(`VCVTDQ2PS`, `VCVTPS2PD`, `VCVTDQ2PD`, and the `VCVTPD2DQX`/`Y` and
+`VCVTTPD2DQX`/`Y` spellings, whose length follows the wider source) and
+`VFMADD231PD` — and the no-operand `VZEROUPPER`, together with `VPERMD` and
 the scalar families (`CMOVcc`, `SETcc`, `LZCNT`/`TZCNT`, the extending moves,
 `CVTSx2SD`, `IMUL3`) and the EVEX (AVX-512) prefix — the four-byte prefix with
 5-bit register fields (Z0–Z31, X/Y 16–31, with the mod=11 quirk that carries
@@ -224,7 +228,11 @@ explicit merging/zeroing masks — written the way Go writes them, as a K
 operand among the operands plus a `.Z` mnemonic suffix), and the compressed
 disp8×N displacement, whose multiplier follows the memory operand's size —
 covering every instruction the go-flac and go-lz4 AVX2/AVX-512 kernels use,
-plus the common AVX-512 F/BW integer set.  Every encoding is validated two ways: by
+plus the common AVX-512 F/BW integer set and the floating-point and
+conversion set (the packed double arithmetic, the scalar SD/SS forms —
+whose EVEX encodings serve masked and zeroing use — `VMOVDDUP`, and the
+width-changing conversions, including the `VCVTPD2DQ`/`VCVTTPD2DQ` family
+whose length follows the wider source operand).  Every encoding is validated two ways: by
 round-trip decoding through `golang.org/x/arch`, and byte-for-byte against
 the machine code the real Go assembler emits — a comparison that holds for
 whole functions: all 27 functions of both kernels assemble to exactly the Go
@@ -237,7 +245,8 @@ behind the code and resolves references to them (`mask<>(SB)`) to
 RIP-relative loads whose displacements point inside the resulting image, so
 the bytes are self-consistent at any base address.  External (non-file-local)
 symbols are rejected: they need object-file emission, which — together with
-EVEX masking/zeroing and the other architectures — is the rest of Phase 2.
+the remaining EVEX forms and the other architectures — is the rest of
+Phase 2.
 
 ## Extension points