nvc0: fix gl_SampleMaskIn computation

The SAMPLEMASK semantic should only return the bits set covered by the
current invocation. However we were always retrieving the covmask, which
returns the covered samples of the whole pixel.

When not doing per-sample invocation, this is precisely what we want.
However when doing per-sample invocation, we have to select the
sampleid'th bit and only return that. Furthermore, this means that we
have to have a 1:1 correlation for invocations and samples.

This fixes most

dEQP-GLES31.functional.shaders.sample_variables.sample_mask_in.*

tests. A few failures remain due to disagreements about nr_samples==1
logic as well as what happens with MSAA x2 RTs when the shading fraction
is 0.5.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
index d59950eb6f4..69e1a341bc3 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
@@ -1273,6 +1273,13 @@ bool Source::scanDeclaration(const struct tgsi_full_declaration *decl)
       case TGSI_SEMANTIC_DRAWID:
          info->prop.vp.usesDrawParameters = true;
          break;
+      case TGSI_SEMANTIC_SAMPLEID:
+      case TGSI_SEMANTIC_SAMPLEPOS:
+         info->prop.fp.persampleInvocation = true;
+         break;
+      case TGSI_SEMANTIC_SAMPLEMASK:
+         info->prop.fp.usesSampleMaskIn = true;
+         break;
       default:
          break;
       }