Auto synthesis of IDifferntial interface methods. (#2469)

* Auto synthesis of IDifferntial interface methods.

* Add comments.

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

2 files changed, 51 insertions, 0 deletions

diff --git a/tests/autodiff/differential-method-synthesis.slang b/tests/autodiff/differential-method-synthesis.slang
new file mode 100644
index 000000000..73afc4411
--- /dev/null
+++ b/tests/autodiff/differential-method-synthesis.slang
@@ -0,0 +1,45 @@
+// Tests automatic synthesis of Differential type and method requirements.
+
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -shaderobj -output-using-type
+//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;
+
+struct B : IDifferentiable
+{
+    float x;
+}
+
+struct A : IDifferentiable
+{
+    B b;
+    float y;
+};
+
+typedef __DifferentialPair<A> dpA;
+
+A nonDiff(A a)
+{
+    return a;
+}
+
+__differentiate_jvp A f(A a)
+{
+    A aout;
+    aout.y = 2 * a.b.x;
+    aout.b.x = 5 * a.b.x;
+
+    return nonDiff(aout);
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    {
+        A a = {1.0, 2.0};
+        A.Differential b = {0.2};
+        dpA dpa = dpA(a, b);
+        outputBuffer[0] = __jvp(f)(dpa).d().b.x;                    // Expect: 0
+    }
+}
diff --git a/tests/autodiff/differential-method-synthesis.slang.expected.txt b/tests/autodiff/differential-method-synthesis.slang.expected.txt
new file mode 100644
index 000000000..e070cf84d
--- /dev/null
+++ b/tests/autodiff/differential-method-synthesis.slang.expected.txt
@@ -0,0 +1,6 @@
+type: float
+0.000000
+0.000000
+0.000000
+0.000000
+0.000000