Mesa (master): nv50/ir: saturate depth writes

[Ilia Mirkin]

Module: Mesa
Branch: master
Commit: 6711f159d94f37f3f45d36a8cb172cfc00692875
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6711f159d94f37f3f45d36a8cb172cfc00692875

Author: Ilia Mirkin <imirkin at alum.mit.edu>
Date:   Sun Mar 20 13:11:01 2016 -0400

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 <imirkin at alum.mit.edu>

---

 src/gallium/drivers/nouveau/codegen/nv50_ir_from_tgsi.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

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 611d5f9..4f012cd 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);
+         }
       }
    }
 }