[LLVMdev] Proposal: intp type

[Kenneth Uildriks]

On Tue, Nov 10, 2009 at 6:10 PM, Talin <viridia at gmail.com> wrote:
> In my case, I've been attempting to build a target-neutral frontend. In my
> tool chain, the target is specified at link time, not at compile time. Among
> other things, that means that the same IR file can be used for multiple
> targets.

That's the direction I'm going in too.

>
> What strikes me is how tantalizingly close LLVM comes to being able to do
> this. I am surprised, for example, that I can general all of the DWARF
> debugging structures without ever having to choose a target machine. Most
> things can be done quite easily without knowing the exact size of a pointer.
> When it comes to being able to "generate once, run anywhere", LLVM is like
> 99.5% of the way there. Which makes that last remaining .5% particularly
> vexing.
>
> There's only a tiny handful of fairly esoteric cases which require selecting
> a target before you generate IR. Unfortunately, the "pointer the same size
> as an int" is one of these rare cases -  it is something that is very
> painful to try and work around. (A similar esoteric use case is: "which of
> the following two types is larger, 3 x int32 or 2 x {}*? -- i.e. the union
> problem.)

I'm willing to spend some time on adding intp to LLVM... my
front-end's standard libraries would be cleaner and more portable that
way.