st/mesa: Replace glsl_to_tgsi() with glsl_to_nir() and nir_to_tgsi(). (!8044) · Merge requests · Mesa / mesa

    st/mesa: Always generate NIR from GLSL, and use nir_to_tgsi for TGSI drivers.
    
    The NIR path through the frontend is effectively the only one maintained
    for a quite a while now.  We can see that effect with !15540, where the
    TGSI generation path was regressed to assertion fail on real-world
    shaders, and nobody noticed until I came along trying to test the
    NIR-to-TGSI transition.
    
    We already have a nir_to_tgsi() call for translating NIR representation
    for ARB programs into TGSI before handing them off to the driver.  This
    change makes that path get taken for GLSL programs as well.
    
    This is the minimum change to get all the drivers on NIR from GLSL, to
    give a simple commit to bisect too.  The dead code removal comes next.
    
    Now every driver benefits from shared NIR optimizations for GLSL, and we
    can start retiring GLSL optimizations.

Removing 20k lines and unifying major paths through the compiler feels well worth finishing this off. Some remaining issues: