nv50/ir: saturate depth writes

Apparently there's no post-FS clamping logic, so we have to do this by
hand. The depth will never be outside of the 0..1 range, even on
floating point zeta buffers, so this should be safe.

Fixes dEQP-GLES3.functional.fbo.depth.*clamp.* which tests writing
invalid values on various zeta buffer formats.

Signed-off-by: Ilia Mirkin <[email protected]>

1 files changed, 4 insertions, 1 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 611d5f9c3ed..4f012cd3b91 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp
@@ -3536,8 +3536,11 @@ Converter::exportOutputs()
          Symbol *sym = mkSymbol(FILE_SHADER_OUTPUT, 0, TYPE_F32,
                                 info->out[i].slot[c] * 4);
          Value *val = oData.load(sub.cur->values, i, c, NULL);
-         if (val)
+         if (val) {
+            if (info->out[i].sn == TGSI_SEMANTIC_POSITION)
+               mkOp1(OP_SAT, TYPE_F32, val, val);
             mkStore(OP_EXPORT, TYPE_F32, sym, NULL, val);
+         }
       }
    }
 }