DataReader is generally jank - it has a start and end pointer, but the end pointer is generally not used, and all of the vertex loaders mostly bypassed it anyways.
Wrapper code (the vertex loaer test, as well as Fifo.cpp and OpcodeDecoding.cpp) still uses it, as does the software vertex loader (which is not a subclass of VertexLoader). These can probably be eliminated later.
Rather than makring some parts of VertexLoaderManager dirty in some places and some in others, do it all in VideoState. Also, since CPState no longer contains pointers/non-CP data after d039b1bc0d, we can just use p.Do on it instead of manually saving each field.
https://bugs.dolphin-emu.org/issues/12977 indicates that this happens on startup of Spider-Man 2, even in single-core. I don't have the game, so I can't directly determine why this is happening, but presumably real hardware does not hang in this case, so we can make it less obtrusive.
This more accurately represents what's going on, and also ends at 0 instead of 1, making some indexing operations easier. This also changes it so that position_matrix_index_cache actually starts from index 0 instead of index 1.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
They appear to relate to perf queries, and combining them with truely unknown commands would probably hide useful information. Furthermore, 0x20 is issued by every title, so without this every title would be recorded as using an unknown command, which is very unhelpful.
