nak: Rework RA a bit
Instead of tracking pinned things in the register allocator, we split
the register allocator into RegAllocator and PinnedRegAllocator. The
RegAllocator struct only allows for very simple single-SSA allocations
and frees. It tracks locations of everything, what's used, etc. but
otherwise knows nothing about pinning or vectors.
The new PinnedRegAllocator struct wraps a RegAllocator by taking a
mutable reference to it. It provides support for pinning and all the
vector stuff. To destroy a PinnedRegAllocator, finish() is called which
re-places any evicted SSA values and populates an OpParCopy with any
needed copies. Because PinnedRegAllocator owns a mutable reference to
the RegAllocator, it's impossible to mix uses of PinnedRegAllocator and
RegAllocator. This ensures that, for as long as the pinned version
exists, nothing can be allocated which migh escape the pinning.
This fixes a bunch of corner cases when register pressure gets tight.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24998>
2 files changed
