Cleaned up legacy differential type handling + type casting bugfixes (#2660)

5 files changed, 47 insertions, 7 deletions

diff --git a/source/slang/slang-ir-autodiff-fwd.cpp b/source/slang/slang-ir-autodiff-fwd.cpp
index 214e97ff6..26d84720f 100644
--- a/source/slang/slang-ir-autodiff-fwd.cpp
+++ b/source/slang/slang-ir-autodiff-fwd.cpp
@@ -1363,8 +1363,6 @@ InstPair ForwardDiffTranscriber::transcribeInstImpl(IRBuilder* builder, IRInst*
     case kIROp_Neq:
         return transcribeBinaryLogic(builder, origInst);
 
-    case kIROp_CastIntToFloat:
-    case kIROp_CastFloatToInt:
     case kIROp_MakeVector:
     case kIROp_MakeMatrix:
     case kIROp_MakeMatrixFromScalar:
@@ -1470,6 +1468,8 @@ InstPair ForwardDiffTranscriber::transcribeInstImpl(IRBuilder* builder, IRInst*
     case kIROp_PackAnyValue:
     case kIROp_UnpackAnyValue:
     case kIROp_GetNativePtr:
+    case kIROp_CastIntToFloat:
+    case kIROp_CastFloatToInt:
         // A call to createDynamicObject<T>(arbitraryData) cannot provide a diff value,
         // so we treat this inst as non differentiable.
         // We can extend the frontend and IR with a separate op-code that can provide an explicit diff value.
diff --git a/source/slang/slang-ir-autodiff.h b/source/slang/slang-ir-autodiff.h
index 38e4636ac..7bcd4c90b 100644
--- a/source/slang/slang-ir-autodiff.h
+++ b/source/slang/slang-ir-autodiff.h
@@ -173,8 +173,8 @@ struct DifferentiableTypeConformanceContext
         case kIROp_FloatType:
         case kIROp_HalfType:
         case kIROp_DoubleType:
-        case kIROp_VectorType:
             return origType;
+            
         case kIROp_ArrayType:
         {
             auto diffElementType = (IRType*)getDifferentialForType(
diff --git a/source/slang/slang-ir-ssa.cpp b/source/slang/slang-ir-ssa.cpp
index 20a8d7d13..d8246edae 100644
--- a/source/slang/slang-ir-ssa.cpp
+++ b/source/slang/slang-ir-ssa.cpp
@@ -1056,10 +1056,7 @@ bool constructSSA(ConstructSSAContext* context)
 
     // Figure out what variables we can promote to
     // SSA temporaries.
-    if (!(context->promotableVars.getCount() > 0))
-    {
-        identifyPromotableVars(context);
-    }
+    identifyPromotableVars(context);
 
     // If none of the variables are promote-able,
     // then we can exit without making any changes
diff --git a/tests/autodiff/reverse-uint-vector.slang b/tests/autodiff/reverse-uint-vector.slang
new file mode 100644
index 000000000..3c940c5de
--- /dev/null
+++ b/tests/autodiff/reverse-uint-vector.slang
@@ -0,0 +1,40 @@
+//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], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+typedef DifferentialPair<float3> dpfloat3;
+typedef float3.Differential dfloat3;
+
+typedef DifferentialPair<float2> dpfloat2;
+typedef float2.Differential dfloat2;
+
+// This test case should hit a lot of conversion insts
+// kIROp_MakeVectorFromScalar (both uint and float), 
+// kIROp_CastIntToFloat, etc..
+// 
+[BackwardDifferentiable]
+float3 test_uint_offset(float3 x, float3 y)
+{
+    uint3 u4 = 1;
+
+    uint3 u5 = u4 + 2;
+
+    return x + y + u5;
+}
+
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    {
+        dpfloat3 dpx = dpfloat3(float3(2.0, 3.0, 4.0), float3(0.0, 0.0, 0.0));
+        dpfloat3 dpy = dpfloat3(float3(1.5, 2.5, 3.5), float3(0.0, 0.0, 0.0));
+
+        __bwd_diff(test_uint_offset)(dpx, dpy, dfloat3(1.0, 2.0, 3.0));
+        outputBuffer[0] = dpx.d.y; // Expect: 2
+        outputBuffer[1] = dpy.d.y; // Expect: 2
+    }
+
+}
\ No newline at end of file
diff --git a/tests/autodiff/reverse-uint-vector.slang.expected.txt b/tests/autodiff/reverse-uint-vector.slang.expected.txt
new file mode 100644
index 000000000..4ca096282
--- /dev/null
+++ b/tests/autodiff/reverse-uint-vector.slang.expected.txt
@@ -0,0 +1,3 @@
+type: float
+2.000000
+2.000000
\ No newline at end of file