Alias

public struct Alias : IRGlobal

An Alias represents a global alias in an LLVM module - a new symbol and corresponding metadata for an existing global value.

An Alias, unlike a function or global variable declaration, does not create any new data in the resulting object file. It is merely a new name for an existing symbol or constant. The aliased value (the aliasee) must be either another global value like a function, global variable, or even another alias, or it must be a constant expression.

Linkers make no guarantees that aliases will be preserved in the final object file. Aliases where the address is known to be relevant should be marked with the appropriate UnnamedAddressKind value. If this value is not none, the alias is guaranteed to have the same address as the aliasee. Else, the alias is guaranteed to point to the same content as the aliasee, but may reside at a different address.

If the aliasee is a constant value, LLVM places additional restrictions on its content in order to maintain compatibility with the expected behavior of most linkers:

  • The constant expression may not involve aliases with weak linkage. Such weak aliases cannot be guaranteed to be stable in the final object file.
  • The constant expression may not involve global values requiring a relocation such as a global function or global variable declared but not defined within its module.

  • Retrieves the underlying LLVM value object.

    Declaration

    Swift

    public func asLLVM() -> LLVMValueRef

  • The target value of this alias.

    The aliasee is required to be another global value or constant

    Declaration

    Swift

    public var aliasee: IRValue { get set }

  • Retrieves the previous alias in the module, if there is one.

    Declaration

    Swift

    public func previous() -> Alias?

  • Retrieves the next alias in the module, if there is one.

    Declaration

    Swift

    public func next() -> Alias?