I meant to make this comment earlier but have been busy with other stuff.
I like these optimizations in terms of the code they generate. Good work on
figuring those out! That said, I'm a little pensive about adding more
GLSL-IR-specific stuff to fs_visitor that we'll just have to rewrite for
NIR.
The GLSL compiler optimizes the pattern
result = [!]gl_FrontFacing ? x : y;
where x and y are ±0.0 and ±1.0 into
result = [-]b2f([!]gl_FrontFacing);
We can do these expressions in two instructions.
total instructions in shared programs: 5928518 -> 5927775 (-0.01%)
instructions in affecte
