Merge gingerBill's latest into bill/rexcode. His changes: minimize the
Instruction/Operand structs across ISAs with packed raw-unions (+ the
compiler support for #raw_union #packed), the new core:rexcode/wasm arch
and wasm/module, encode() now returns (byte_count, ok) instead of a Result
struct, decode_one made public, and assorted formatting/inlining.
Conflict: arm64/tests/pipeline_smoke.odin CSEL test -- kept the generated
4-arg inst_csel(dst,src,src2,cond) (mnemonic_builders.odin is generated,
not from Bill's branch) and adopted Bill's (byte_count, success) encode
signature.
Required rebuilding ./odin from the merged source for the packed-union
syntax. Re-validated after the repack: regenerated all artifacts
(idempotent -- no spurious churn), all 10 arches gen/builders/check/test
green, and byte-compared the new arm32 BF + mips PS/MMI/DSP/R6 forms to
confirm no field truncation. arm64/arm32/mips still 100%.
New REL19/REL18 operand types + BRANCH_19/BRANCH_18 encodings + REL_PC19/
REL_PC18 relocations (R6 PC-relative semantics: offset is relative to the
instruction's own address, no delay-slot adjustment; LDPC aligns the PC
down to 8 and scales by 8). LWPC (mips32r6), LWUPC/LDPC (mips64r6).
Byte-exact vs llvm-mc and decode-clean; 281 tests green.
New EXT_SIZE encoding (5-bit extract size at 25:21). EXTPDP (immediate
size), and the variable forms EXTPDPV / EXTRV_R.W / EXTRV_RS.W / EXTRV_S.H
(extract via a GPR-specified position). Byte-exact vs llvm-mc and decode-
clean; 281 tests green.
New AC_NUM (accumulator ac0..ac3 at bits 12:11) and SHILO_IMM (signed
6-bit at 25:20) encodings. DPA/DPAX/DPS/DPSX.W.PH and MAQ_S/MAQ_SA.W.PHL/
PHR (multiply-accumulate into a DSP accumulator), plus MTHLIP, SHILOV and
SHILO (accumulator shift). Spot-checked byte-exact vs llvm-mc and decode-
clean, including a negative SHILO immediate; 281 tests green.
BZ/BNZ .B/.H/.W/.D/.V (branch if any/all elements zero/non-zero): a
specgen branch emitter that derives the opcode+Wt bits then marks the
16-bit PC-relative offset variable, reusing the existing REL16/BRANCH_16
relocation machinery. The offset is emitted as a relocation (label
target). 10 forms, opcode+Wt byte-exact vs llvm-mc and decode-clean.
The R6 two-/one-register compact branches (BEQC/BNEC/BLTC/BGEC/.../BLTZC)
are deferred: they share POP major opcodes disambiguated only by the
rs/rt relationship, which the opcode+mask decode model can't express
without operand-aware logic. 281 tests green.
New FR (FP reg at 25:21) encoding for the COP1X 4-register fused
multiply-adds MADD/MSUB/NMADD/NMSUB.S/.D. New GPR_AT_6 / GPR_AT_11
encodings (GPR in a vector-register slot, with correct GPR decode) for
MSA COPY_S/U (lane->GPR) and INSERT (GPR->lane). DSP two-register
PRECEQU/PRECEU (.PH.QBLA/QBRA) and REPLV (.PH/.QB). Control ops DI/EI and
RDHWR. 25 forms; spot-checked byte-exact vs llvm-mc and decode-clean; 281
tests green.
New MSA_BIT_SHIFT / MSA_ELM_IDX / MSA_I8 encodings (the data-format marker
is fixed in the entry bits; the operand drives the low bits; decode infers
df from the marker). SLLI/SRAI/SRLI (.B/.H/.W/.D shift), SPLATI/SLDI
(element index), SPLAT/SLD (GPR index), VSHF (.B/.H/.W/.D shuffle), and
the I8 forms ANDI/ORI/XORI/NORI/BMNZI/BMZI/BSELI.B + SHF.B/H/W. 42 forms.
Spot-checked byte-exact vs llvm-mc and decode-clean across all formats;
281 tests green.
Each ISA's hand-written ENCODING_TABLE (the single source of truth) now lives
in a per-arch tablegen/ metaprogram that flattens it and serializes committed
binary blobs; the library #loads those into @(rodata) at compile time rather
than compiling a table body. No arch keeps encoding_table.odin or
decoding_tables.odin -- only a generated tables.odin loader and tables/*.bin.
* Two-stage, type-checked pipeline: tablegen Stage A emits human-readable
generated Odin, which compiles and serializes the blobs in Stage B.
* encode() goes through encoding_forms(m); decoders are unchanged apart from
x86's flattened 2-D index. Decode tables are byte-identical to the old ones.
* build.lua: a LuaJIT driver for the metaprograms, validations, and tests,
with cross-platform gating and a clear report.
* Docs refreshed; the obsolete forward-looking plan in cross_arch_design.md
trimmed to what was actually built.
* Attribution headers added to all rexcode source files; the generators emit
them so generated files keep them.
