nak: Place most Op structs in Box<>
Between this and the previous few commits, the Box<> has moved from
outside of Instr to inside the Op enum. This provides a few benefits:
1. We no longer need to allocate for the worst-case Op on every
instruction. For example, OpIAdd3X is 232 bytes and OpBra is 40
bytes, which means we can save some memory on OpBra if we only
allocate those 40 bytes.
2. The Op discriminant is available without chasing a pointer. The type
of op is probably the most frequently used field, and this should
benefit most passes that care about what type of Op they're
handling.
3. Small Ops don't need any indirection at all. For example, OpPBk is
only 4 bytes, which means we can just store it directly in less
space than a pointer.
Compared to Box<Instr>, this is around a 1.4% shader compile time
improvement.
Acked-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Reviewed-by: Seán de Búrca <leftmostcat@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37315>
7 files changed
