- OpFunctionParameter: the entry block's Block.params round-trip as
OpFunctionParameter (emitted between OpFunction and the entry OpLabel, decoded
back onto the entry block).
- encode computes bound (max <id> + 1) when the caller leaves it 0; a non-zero
bound (e.g. from decode) is preserved, so re-encode is stable.
- Trailing operands an enum value/bit pulls in (MemoryAccess Aligned's alignment,
...) are captured on decode as literals, so enum-parameter instructions
re-encode byte-exact.
Tests: param_function + load_aligned added -> 5 passed.
The inverse of the encoder: read the header (detecting endianness from the
magic word), walk the instruction stream, and lower each instruction by opcode
back into the structured Module -- the ir core (types/constants/globals/
functions, the generic table-driven operation decode), the SPIR-V sections
(preamble / debug / annotations), and the flat <id> space into the side id
tables (with an id->Type_Ref map so type-naming operands recover TYPE operands).
Single allocator pass (context.allocator), one reused per-instruction word
scratch buffer. Validated: encode -> decode -> re-encode is byte-exact on the
void compute main module (116 bytes; caps/types/functions/blocks/ops/ids/bound
all recovered). Same gaps as the encoder (OpFunctionParameter, ARRAY/bool,
enum-parameter operands); big-endian sources a later refinement.
