Fix SPIRV emit for `Flat` decoration and TessLevel builtin. (#4318)

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/spirv/flat.slang b/tests/spirv/flat.slang
new file mode 100644
index 000000000..660f61216
--- /dev/null
+++ b/tests/spirv/flat.slang
@@ -0,0 +1,27 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+
+// Check that we don't emit duplicate Flat decorations for the same variable.
+
+// CHECK: OpDecorate %vo_a Flat
+// CHECK-NOT: OpDecorate %vo_a Flat
+
+struct VertexOutput
+{
+    nointerpolation int a : SOME_VALUE;
+    float4              b : SV_Position;
+};
+
+[shader("vertex")]
+VertexOutput Vertex()
+{
+    VertexOutput out;
+    out.a = 0;
+    out.b = float4(0, 0, 0, 1);
+    return out;
+}
+
+[shader("fragment")]
+float4 Fragment(in VertexOutput vo)
+{
+    return float4(float(vo.a), 0, 0, 1);
+}
\ No newline at end of file