Support `constref` parameters passing. (#3249)

* Support `constref` parameters passing.

* Fix.

* Fix.

* Add test and diagnostic on mix use of __constref and no_diff.

* check for [constref] on differentiable member method.

---------

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

1 files changed, 41 insertions, 0 deletions

diff --git a/tests/autodiff/constref-param.slang b/tests/autodiff/constref-param.slang
new file mode 100644
index 000000000..5bce8e304
--- /dev/null
+++ b/tests/autodiff/constref-param.slang
@@ -0,0 +1,41 @@
+//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(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-cuda -compute -shaderobj -output-using-type
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-cpu -compute -shaderobj -output-using-type
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+struct NonDiff
+{
+    float a;
+}
+
+[Differentiable]
+float myFunc(__constref NonDiff fIn, float x, __constref no_diff float y)
+{
+    return x * fIn.a + y;
+}
+
+// test that the ordering of no_diff and __constref doesn't matter.
+[Differentiable]
+float myFunc2(__constref NonDiff fIn, float x, no_diff __constref float y)
+{
+    return x * fIn.a + y;
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    float a = 10.0;
+    NonDiff fIn = { a };
+    DifferentialPair<float> dpx = DifferentialPair<float>(4.f, 1.f);
+    float rs = __fwd_diff(myFunc)(fIn, dpx, 1.0).d;
+    float rs2 = __fwd_diff(myFunc2)(fIn, dpx, 1.0).d;
+
+    // CHECK: 10.0
+    // CHECK: 10.0
+
+    outputBuffer[0] = rs;
+    outputBuffer[1] = rs2;
+}