Added support for nested calls (#2562)

* Added initial support for nested calls

* removed comments

Co-authored-by: Yong He <yonghe@outlook.com>

4 files changed, 37 insertions, 23 deletions

diff --git a/tests/autodiff/reverse-nested-calls.slang b/tests/autodiff/reverse-nested-calls.slang
new file mode 100644
index 000000000..2b55efd60
--- /dev/null
+++ b/tests/autodiff/reverse-nested-calls.slang
@@ -0,0 +1,29 @@
+//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;
+
+typedef DifferentialPair<float> dpfloat;
+typedef float.Differential dfloat;
+
+[BackwardDifferentiable]
+float g(float y)
+{
+    return 4.0f * y;
+}
+
+[BackwardDifferentiable]
+float f(float x)
+{
+    return 3.0f * g(2.0f * x);
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    dpfloat dpa = dpfloat(1.0, 0.0);
+
+    __bwd_diff(f)(dpa, 1.0f);
+    outputBuffer[0] = dpa.d; // Expect: 24.0
+}
diff --git a/tests/autodiff/reverse-nested-calls.slang.expected.txt b/tests/autodiff/reverse-nested-calls.slang.expected.txt
new file mode 100644
index 000000000..0a39c4da6
--- /dev/null
+++ b/tests/autodiff/reverse-nested-calls.slang.expected.txt
@@ -0,0 +1,6 @@
+type: float
+24.000000
+0.000000
+0.000000
+0.000000
+0.000000
diff --git a/tests/autodiff/reverse-struct-types.slang b/tests/autodiff/reverse-struct-types.slang
index 699e50480..d2b52a008 100644
--- a/tests/autodiff/reverse-struct-types.slang
+++ b/tests/autodiff/reverse-struct-types.slang
@@ -9,27 +9,6 @@ struct A : IDifferentiable
 {
     float x;
     float y;
-
-    [__unsafeForceInlineEarly]
-    static Differential dzero()
-    {
-        Differential b = {0.0, float.dzero()};
-        return b;
-    }
-
-    [__unsafeForceInlineEarly]
-    static Differential dadd(Differential a, Differential b)
-    {
-        Differential o = {a.x + b.x, 0.0};
-        return o;
-    }
-
-    [__unsafeForceInlineEarly]
-    static Differential dmul(This a, Differential b)
-    {
-        Differential o = {a.x * b.x, 0.0};
-        return o;
-    }
 };
 
 typedef DifferentialPair<A> dpA;
@@ -56,7 +35,7 @@ void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
         A.Differential dout = {1.0, 1.0};
         
         __bwd_diff(f)(dpa, dout);
-        outputBuffer[0] = dpa.d.x; // Expect: 10
+        outputBuffer[0] = dpa.d.x; // Expect: 7
         outputBuffer[1] = dpa.d.y; // Expect: 0
     }
 }
diff --git a/tests/autodiff/reverse-struct-types.slang.expected.txt b/tests/autodiff/reverse-struct-types.slang.expected.txt
index 82bc8f733..b94f4fec6 100644
--- a/tests/autodiff/reverse-struct-types.slang.expected.txt
+++ b/tests/autodiff/reverse-struct-types.slang.expected.txt
@@ -1,5 +1,5 @@
 type: float
-5.000000
+7.000000
 0.000000
 0.000000
 0.000000