[LLVMdev] simulating c style unions in LLVM

[Eli Friedman]

On Mon, Jun 29, 2009 at 11:09 PM, Carter Cheng<carter_cheng at yahoo.com> wrote:
>
> I am trying to create a boxed tagged datatype for a language where it is necessary to resolve the type at runtime. If I were writing an interpreter in C- it would most likely look something like this-
>
> struct
> {
>    unsigned tag;
>    union { long Int; double Float; .... }
> }
>
> Is there a standard way for constructing a type like this in LLVM?

You have to write it using bitcasts.  Try looking at llvm-gcc or clang
output for a rough outline.

-Eli