Extend `no_diff` to support subscript operations on resources and array variables… (#2981)

* Extend `no_diff` to support subscript operations on resources and array variables

* Update autodiff.slang.expected

3 files changed, 32 insertions, 3 deletions

diff --git a/tests/autodiff/no-diff-array-access.slang b/tests/autodiff/no-diff-array-access.slang
new file mode 100644
index 000000000..df8c8faa0
--- /dev/null
+++ b/tests/autodiff/no-diff-array-access.slang
@@ -0,0 +1,23 @@
+//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 DifferentialPair<float3> dpfloat3;
+
+[ForwardDifferentiable]
+float f(float x, float[3] y)
+{
+    return x * no_diff(outputBuffer[4]) + y[2] * x * no_diff(y[1]);
+}
+
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    var dpx = fwd_diff(f)(DifferentialPair<float>(1.0f, 1.0f), DifferentialPair<float[3]>( { 1.0f, 2.0f, 3.0f }, { 1.0f, 2.0f, 3.0f }));
+    outputBuffer[0] = dpx.p; // Expect: 6.0
+    outputBuffer[1] = dpx.d; // Expect: 12.0
+}
diff --git a/tests/autodiff/no-diff-array-access.slang.expected.txt b/tests/autodiff/no-diff-array-access.slang.expected.txt
new file mode 100644
index 000000000..504eaec3e
--- /dev/null
+++ b/tests/autodiff/no-diff-array-access.slang.expected.txt
@@ -0,0 +1,6 @@
+type: float
+6.000000
+12.000000
+0.000000
+0.000000
+0.000000
diff --git a/tests/diagnostics/autodiff.slang.expected b/tests/diagnostics/autodiff.slang.expected
index d075b9406..95da2a6d3 100644
--- a/tests/diagnostics/autodiff.slang.expected
+++ b/tests/diagnostics/autodiff.slang.expected
@@ -1,12 +1,12 @@
 result code = -1
 standard error = {
-tests/diagnostics/autodiff.slang(35): error 38031: 'no_diff' can only be used to decorate a call.
+tests/diagnostics/autodiff.slang(30): error 38031: 'no_diff' can only be used to decorate a call or a subscript operation
     float x1 = no_diff x; // invalid use of no_diff here.
                ^~~~~~~
-tests/diagnostics/autodiff.slang(36): error 38032: use 'no_diff' on a call to a differentiable function has no meaning.
+tests/diagnostics/autodiff.slang(31): error 38032: use 'no_diff' on a call to a differentiable function has no meaning.
     return no_diff f(x);  // no_diff on a differentiable call has no meaning.
            ^~~~~~~
-tests/diagnostics/autodiff.slang(41): error 38033: cannot use 'no_diff' in a non-differentiable function.
+tests/diagnostics/autodiff.slang(36): error 38033: cannot use 'no_diff' in a non-differentiable function.
     return no_diff nonDiff(x); // no_diff in a non-differentiable function
            ^~~~~~~
 }