tree a48278ba227e71860932632e9b2cbde40443c498
parent 009d129103eebe3eb60222971a3734c7274ee3c5
author Stephen White <senorblanco@chromium.org> 1643992893 +0000
committer Tint LUCI CQ <tint-scoped@luci-project-accounts.iam.gserviceaccount.com> 1643992893 +0000

GLSL: fix sample_index, sample_mask and bitcasts

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>