Fix crash when writing to `no_diff` out parameter. (#3308)

* Fix crash when writing to `no_diff` out parameter.

* Fix.

---------

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

1 files changed, 30 insertions, 0 deletions

diff --git a/tests/autodiff/no-diff-out.slang b/tests/autodiff/no-diff-out.slang
new file mode 100644
index 000000000..c8085a05f
--- /dev/null
+++ b/tests/autodiff/no-diff-out.slang
@@ -0,0 +1,30 @@
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-slang -compute -shaderobj -output-using-type
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+typedef DifferentialPair<float> dpfloat;
+
+[Differentiable]
+float test(float x, no_diff out float y)
+{
+    if (x == 1.0)
+        y = 0.0;
+    return x * x;
+}
+
+[Differentiable]
+float caller(float x, no_diff out float y)
+{
+    return test(x, y);
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    var p = diffPair(3.0, 0.0);
+    bwd_diff(caller)(p, 1.0);
+    outputBuffer[dispatchThreadID.x] = p.d;
+    // CHECK: 6.0
+}