Full address insts elimination for backward autodiff. (#2604)

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

1 files changed, 48 insertions, 0 deletions

diff --git a/tests/autodiff/reverse-struct-multi-write.slang b/tests/autodiff/reverse-struct-multi-write.slang
new file mode 100644
index 000000000..dd12c7d3d
--- /dev/null
+++ b/tests/autodiff/reverse-struct-multi-write.slang
@@ -0,0 +1,48 @@
+
+//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;
+
+struct A : IDifferentiable
+{
+    float x;
+    float y;
+};
+
+[BackwardDifferentiable]
+A f(A a)
+{
+    // Read/writes to local struct variables won't be SSA'd out by default.
+    // The backward diff preparation pass will kick in to create temp vars for them.
+    A aout;
+    aout.y = 2 * a.x;
+    aout.y = aout.y + 2 * a.x;
+    aout.x = aout.y + 5 * a.x;
+
+    // The result should be equivalent to:
+    /*
+    A aout;
+    var tmp = 2 * a.x;
+    tmp = tmp + 2 * a.x;
+    aout.y = tmp;
+    aout.x = tmp + 5 * a.x;
+    */
+    return aout;
+
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    A a = {1.0, 2.0};
+
+    var dpa = diffPair(a);
+
+    A.Differential dout = {1.0, 1.0};
+    
+    __bwd_diff(f)(dpa, dout);
+    outputBuffer[0] = dpa.d.x; // Expect: 13
+    outputBuffer[1] = dpa.d.y; // Expect: 0
+}