Autodiff support for dynamically dispatched generic method. (#2846)

* Autodiff support for dynamically dispatched generic method.

* Fix.

* Support dynamically dispatched generic type.

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/tests/autodiff/dynamic-object-bwd-diff-2.slang b/tests/autodiff/dynamic-object-bwd-diff-2.slang
new file mode 100644
index 000000000..bb0a69b28
--- /dev/null
+++ b/tests/autodiff/dynamic-object-bwd-diff-2.slang
@@ -0,0 +1,61 @@
+// Test calling backward differentiable function through dynamic dispatch, where the interface
+// being dispatched inherits from IDifferentiable, so that `this` is differentiable.
+
+//DISABLED_TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj -output-using-type
+//DISABLED_TEST(compute, vulkan):COMPARE_COMPUTE_EX:-vk -compute -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[anyValueSize(16)]
+interface IInterface : IDifferentiable
+{
+    [BackwardDifferentiable]
+    float calc(float x);
+}
+
+struct C : IInterface
+{
+    [BackwardDifferentiable]
+    float calc(float x) { return 2 * x; }
+}
+
+struct A : IInterface
+{
+    float a;
+    [BackwardDifferentiable]
+    float calc(float x)
+    {
+        return a * x * x;
+    }
+};
+
+
+[BackwardDifferentiable]
+float run(int id, float x, no_diff float y)
+{
+    IInterface obj = createDynamicObject<IInterface>(id, y);
+    C c = {};
+    return obj.calc(x);
+}
+
+//TEST_INPUT: type_conformance A:IInterface = 0
+//TEST_INPUT: type_conformance C:IInterface = 1
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    {
+        var p = diffPair(3.0);
+
+        __bwd_diff(run)(0, p, 0.5, 1.0f);
+        outputBuffer[0] = p.d; // A.calc, expect 3
+    }
+
+    {
+        var p = diffPair(3.0);
+
+        __bwd_diff(run)(1, p, 1.5, 1.0f);
+        outputBuffer[1] = p.d; // c.calc, expect 2
+    }
+}