Fix `UseGraph::replace` (#6395)

* Fix `UseGraph::isTrivial()` test.

* Fix.

* Fix.

* Refactor `UseGraph` and `UseChain`

* Update slang-ir-autodiff-primal-hoist.cpp

* Update all auto-diff locations that handle pointers to treat user pointers as regular values

* Update test to use direct-SPIRV only

---------

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

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/autodiff/dynamic-dispatch-ptr.slang b/tests/autodiff/dynamic-dispatch-ptr.slang
new file mode 100644
index 000000000..3f2269f78
--- /dev/null
+++ b/tests/autodiff/dynamic-dispatch-ptr.slang
@@ -0,0 +1,43 @@
+//TEST:COMPARE_COMPUTE(filecheck-buffer=CHECK):-vk -output-using-type -emit-spirv-directly
+
+//CHECK: 1.0 
+
+//TEST_INPUT: type_conformance Sensor:ISensor = 1;
+
+[anyValueSize(16)]
+interface ISensor
+{
+    [Differentiable]
+    float4 splat(float4 point);
+}
+
+struct Sensor : ISensor
+{
+    [Differentiable]
+    float4 splat(float4 point)
+    {
+        return point;
+    }
+}
+
+[Differentiable]
+float4 splat(ISensor* obj, float4 point)
+{
+    return obj->splat(point);
+}
+
+//TEST_INPUT: set s = ubuffer(data=[0 0 1 0 0 0 0 0])
+uniform ISensor *s;
+
+//TEST_INPUT: set outBuffer = out ubuffer(data=[0 0 0 0], stride=4)
+RWStructuredBuffer<float4> outBuffer;
+
+[shader("compute"), numthreads(1, 1, 1)]
+void computeMain(
+    uint3 id : SV_DispatchThreadID
+)
+{
+    DifferentialPair<float4> dp;
+    bwd_diff(splat)(s, dp, float4(1.0f));
+    outBuffer[id.x] = dp.d;
+}
\ No newline at end of file