2 files changed, 71 insertions, 0 deletions
diff --git a/tests/autodiff/matrix-row-major-dedup.slang b/tests/autodiff/matrix-row-major-dedup.slang
new file mode 100644
index 000000000..a2c792c58
--- /dev/null
+++ b/tests/autodiff/matrix-row-major-dedup.slang
@@ -0,0 +1,51 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -cpu -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -vk -output-using-type
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -d3d11 -output-using-type
+
+// This test verifies that row_major and column_major matrices don't create
+// duplicate DiffPair structs when used together in autodiff code.
+// Before the fix, this would generate compilation errors due to mismatched
+// DiffPair_matrixx3Cfloatx2C3x2C3x3E_0 and DiffPair_matrixx3Cfloatx2C3x2C3x3E_1 types.
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[Differentiable]
+float3 matmul33_row(no_diff float3 v, row_major float3x3 w) {
+    return mul(w, v);
+}
+
+[Differentiable]
+float3 matmul33_col(no_diff float3 v, column_major float3x3 w) {
+    return mul(w, v);
+}
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID) {
+    // Test row_major matrix with meaningful values
+    row_major float3x3 w_row = float3x3(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0);
+    float3 v = float3(1.0, 2.0, 3.0);
+
+    DifferentialPair<row_major float3x3> dpW_row = diffPair(w_row);
+    __bwd_diff(matmul33_row)(v, dpW_row, float3(4.0, 5.0, 6.0));
+    
+    // Write gradients to output buffer to prevent dead code elimination
+    // Expected gradient matrix is dResult ⊗ v = [4,5,6]^T ⊗ [1,2,3] = [[4,8,12],[5,10,15],[6,12,18]]
+    outputBuffer[0] = dpW_row.d[0][0]; // CHECK: 4
+    outputBuffer[1] = dpW_row.d[0][1]; // CHECK: 8  
+    outputBuffer[2] = dpW_row.d[0][2]; // CHECK: 12
+
+    // Test column_major matrix to ensure they share the same DiffPair struct
+    column_major float3x3 w_col = float3x3(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0);
+    DifferentialPair<column_major float3x3> dpW_col = diffPair(w_col);
+    __bwd_diff(matmul33_col)(v, dpW_col, float3(4.0, 5.0, 6.0));
+    
+    outputBuffer[3] = dpW_col.d[1][0]; // CHECK: 5
+    outputBuffer[4] = dpW_col.d[1][1]; // CHECK: 10
+    outputBuffer[5] = dpW_col.d[1][2]; // CHECK: 15
+    
+    // Additional test values from different matrix positions
+    outputBuffer[6] = dpW_row.d[2][0]; // CHECK: 6
+    outputBuffer[7] = dpW_col.d[2][1]; // CHECK: 12
+    outputBuffer[8] = dpW_row.d[2][2]; // CHECK: 18
+}
diff --git a/tests/autodiff/matrix-row-major-dedup.slang.expected.txt b/tests/autodiff/matrix-row-major-dedup.slang.expected.txt
new file mode 100644
index 000000000..ee2ca3883
--- /dev/null
+++ b/tests/autodiff/matrix-row-major-dedup.slang.expected.txt
@@ -0,0 +1,20 @@
+#pragma pack_matrix(column_major)
+#ifdef SLANG_HLSL_ENABLE_NVAPI
+#include "nvHLSLExtns.h"
+#endif
+
+#ifndef __DXC_VERSION_MAJOR
+// warning X3557: loop doesn't seem to do anything, forcing loop to unroll
+#pragma warning(disable : 3557)
+#endif
+
+
+#line 15 "tests/autodiff/matrix-row-major-dedup.slang"
+[numthreads(1, 1, 1)]
+void computeMain(int3 dispathThreadID_0 : SV_DispatchThreadID)
+{
+
+#line 22
+    return;
+}
+