AD: Various fixes around dynamic dispatch (#2820)

* Add a test for the new diff material system

* Various fixes for AD

- inout primal context params converted to out params,
- added attributed types to list of stored types
- used differentiated primal func type instead of type of differentiated func to avoid tangling with user-code differential types.

---------

Co-authored-by: Lifan Wu <lifanw@nvidia.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/autodiff/material2/DiffuseMaterialInstance.slang b/tests/autodiff/material2/DiffuseMaterialInstance.slang
new file mode 100644
index 000000000..e33e3f568
--- /dev/null
+++ b/tests/autodiff/material2/DiffuseMaterialInstance.slang
@@ -0,0 +1,17 @@
+//TEST_IGNORE_FILE:
+
+__exported import IMaterialInstance;
+__exported import IBSDF;
+
+struct DiffuseMaterialInstance : IMaterialInstance
+{
+    float3 albedo;
+
+    [BackwardDifferentiable]
+    float3 eval(const MaterialInstanceData miData, const float3 wi, const float3 wo)
+    {
+        float3 albedo;
+        for (uint i = 0; i < 3; i++) albedo[i] = miData.data[i];
+        return albedo;
+    }
+};