On MSVC builds we treat conversion warnings as errors.

Due to the limitation of GL_MAX_IMAGE_UNITS being low (8) on Intel's and Nvidia's proprietary drivers, we have to reserve an appropriate amount of image bindings for each of the stages. So far games have been observed to use 4 image bindings on the fragment stage (Kirby Star Allies) and 1 on the vertex stage (TWD series).
No games thus far in my limited testing used more than 4 images concurrently and across all currently active programs.
This fixes shader compilation errors on Kirby Star Allies on OpenGL (GLSL/GLASM)

Not required, as PARAMETERS can just be incremented directly.

All registers are now callee-save registers.

RBX and RBP selected for STATE and RESULT because these are most commonly accessed; this is to avoid the REX prefix.
RBP not used for STATE because there are some SIB restrictions, RBX emits smaller code.

Unnecessary since this is just an offset from STATE.

This can be passed in as an argument instead.

Unnecessary variable.

This Reg64 codepath has the exact same behaviour as the Reg32 one.

Pushing GPRs twice.