[mlir][spirv] Fix int type declaration duplication when serializing

mlir/lib/Target/SPIRV/Serialization/Serializer.cpp

@@ -446,6 +446,19 @@ LogicalResult Serializer::processType(Location loc, Type type,
 LogicalResult
 Serializer::processTypeImpl(Location loc, Type type, uint32_t &typeID,
                             SetVector<StringRef> &serializationCtx) {
+
+  // Map unisgned integer types to singless integer types
+  // This is needed otherwise the generated spirv assembly will contain
+  // twice a type declaration (like OpTypeInt 32 0) which is no permitted and
+  // such module could no pass validation. Indeed at MLIR level the two types
+  // are different and lookup in the cache below fails.
+  // Note: This convertion needs to happen here before the type is looked up in
+  // the cache
+  if (type.isUnsignedInteger()) {
+    type = IntegerType::get(loc->getContext(), type.getIntOrFloatBitWidth(),
+                            IntegerType::SignednessSemantics::Signless);
+  }
+
   typeID = getTypeID(type);
   if (typeID)
     return success();