In GLSL, gl_SampleID and gl_SampleMask[In] require the
GL_OES_sample_variables extension, so output:
"#extension GL_OES_sample_variables : require"
in the header if those builtins is used.
Note that extensions must be inserted before the default precision
declaration, but helpers must be inserted after it, so we set a flag
and emit extensions, then the precision declaration, then helpers.
Further fixes:
- use gl_SampleMaskIn for input builtins, gl_SampleMask for output,
necessitating the addition of a storage class to GLSLBuiltinToString()
- fix the handling of gl_SampleMaskIn: it's array<i32> in GLSL, not
array<u32> as in SPIR-V
- centralize conversions for GLSL builtins used as input variables in
FromGLSLBuiltin()
- implement bitcasts on assignment to GLSL builtin output variables,
centralized in ToGLSLBuiltin()
- update the extension handling in the GLSL writer to check for both
sample_index and sample_mask.
- call UnwrapRef() in GLSL's EmitBitcast(). In the test case, we were
not recognizing the argument as a uint, yielding float() instead of
uintBitsToFloat().
Bug: tint:1408, tint:1412, tint:1414
Change-Id: Ie01541eb6e7cdf4e21347341f988bff916346797
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78920
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
a924ffe70c