diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index 52f916e23754..06e6de65f070 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -471,31 +471,22 @@ DLL storage class: exists for defining a dll interface, the compiler, assembler and linker know it is externally referenced and must refrain from deleting the symbol. -Named Types ------------ +Structure Types +--------------- -LLVM IR allows you to specify name aliases for certain types. This can -make it easier to read the IR and make the IR more condensed -(particularly when recursive types are involved). An example of a name -specification is: +LLVM IR allows you to specify both "identified" and "literal" :ref:`structure +types `. Literal types are uniqued structurally, but identified types +are never uniqued. An :ref:`opaque structural type ` can also be used +to forward declare a type which is not yet available. + +An example of a identified structure specification is: .. code-block:: llvm %mytype = type { %mytype*, i32 } -You may give a name to any :ref:`type ` except -":ref:`void `". Type name aliases may be used anywhere a type is -expected with the syntax "%mytype". - -Note that type names are aliases for the structural type that they -indicate, and that you can therefore specify multiple names for the same -type. This often leads to confusing behavior when dumping out a .ll -file. Since LLVM IR uses structural typing, the name is not part of the -type. When printing out LLVM IR, the printer will pick *one name* to -render all types of a particular shape. This means that if you have code -where two different source types end up having the same LLVM type, that -the dumper will sometimes print the "wrong" or unexpected type. This is -an important design point and isn't going to change. +Prior to the LLVM 3.0 release, identified types were structurally uniqued. Only +literal types are uniqued in recent versions of LLVM. .. _globalvars: