Fix for OpUConvert producing invalid opcode when to/from signs differ

source/slang/slang-emit-spirv.cpp

@@ -7308,11 +7308,9 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
             // Perform unsigned conversion first to an unsigned integer of the same width as the
             // result then perform bit cast to the signed result type. This is done because SPIRV's
             // unsigned conversion (`OpUConvert`) requires result type to be unsigned.
-            auto unsignedV = emitOpUConvert(
-                parent,
-                nullptr,
-                builder.getType(getOppositeSignIntTypeOp(toType->getOp())),
-                inst->getOperand(0));
+            auto builderType = getUnsignedTypeFromSignedType(&builder, toTypeV);
+
+            auto unsignedV = emitOpUConvert(parent, nullptr, builderType, inst->getOperand(0));
             return emitOpBitcast(parent, inst, toTypeV, unsignedV);
         }
         else if (fromInfo.isSigned)

source/slang/slang-ir-util.cpp

@@ -2348,6 +2348,45 @@ bool isInstHoistable(IROp op, IRType* type, IRInst* const* fixedArgs)
            isSpecConstOpHoistable(op, type, fixedArgs);
 }
 
+IRType* getUnsignedTypeFromSignedType(IRBuilder* builder, IRType* type)
+{
+    SLANG_RELEASE_ASSERT(isSignedType(type));
+
+    auto elementType = getVectorOrCoopMatrixElementType(type);
+
+    IROp op = type->getOp();
+    switch (op)
+    {
+    case kIROp_MatrixType:
+        {
+            auto unsignedTypeOp = getOppositeSignIntTypeOp(elementType->getOp());
+            auto matType = as<IRMatrixType>(type);
+            SLANG_RELEASE_ASSERT(matType);
+            return builder->getMatrixType(
+                builder->getType(unsignedTypeOp),
+                matType->getRowCount(),
+                matType->getColumnCount(),
+                matType->getLayout());
+        }
+    case kIROp_VectorType:
+        {
+            auto unsignedTypeOp = getOppositeSignIntTypeOp(elementType->getOp());
+            auto vecType = as<IRVectorType>(type);
+            SLANG_RELEASE_ASSERT(vecType);
+            return builder->getVectorType(
+                builder->getType(unsignedTypeOp),
+                vecType->getElementCount());
+        }
+    case kIROp_IntType:
+    case kIROp_Int16Type:
+    case kIROp_Int64Type:
+    case kIROp_Int8Type:
+        return builder->getType(getOppositeSignIntTypeOp(elementType->getOp()));
+    default:
+        return type;
+    }
+}
+
 bool isSignedType(IRType* type)
 {
     switch (type->getOp())

source/slang/slang-ir-util.h

@@ -418,6 +418,8 @@ constexpr bool anyOf(Range&& range, Predicate&& pred)
     return false;
 }
 
+IRType* getUnsignedTypeFromSignedType(IRBuilder* builder, IRType* type);
+
 bool isSignedType(IRType* type);
 } // namespace Slang
 

tests/spirv/uconvert-vector-typecheck.slang

@@ -0,0 +1,20 @@
+//TEST:SIMPLE(filecheck=CHECK): -target spirv
+
+// CHECK: %[[PTR:[0-9a-zA-Z_]+]] = OpVectorShuffle %v2uint %{{.*}} %{{.*}} 0 1
+// CHECK: %{{.*}} = OpUConvert %v2ushort %[[PTR]]
+
+RWTexture2D<uint> tex;
+
+void writeFlags(int2 position, RWTexture2D<uint> flagsTexture, uint flags)
+{
+    flagsTexture[position] = flags;
+}
+
+[shader("compute")]
+[numthreads(1,1,1)]
+void main(uint3 threadId : SV_DispatchThreadID)
+{
+    uint16_t2 position = uint16_t2(threadId.xy);
+    uint flags = 1;
+    writeFlags(position, tex, flags);
+}