[LLVMdev] Broke my tail (call)

[Jon Harrop]

On Tuesday 24 February 2009 14:54:12 Arnold Schwaighofer wrote:
> On Tue, Feb 24, 2009 at 11:50 AM, Jon Harrop <jon at ffconsultancy.com> wrote:
> > Thanks for the clarification. That makes a lot more sense!
> >
> > LLVM's support for structs is wonderful but I don't think they can be
> > called "first-class structs" until all such arbitrary restrictions have
> > been removed, even though the workaround (using sret form) is trivial in
> > this case.
> >
> > Shall I file this as a bug against LLVM?
>
> Yes please do and maybe include the following code which already
> exhibits the error in the bug report.
>
> define fastcc { { i8*, i8* }*, i8*} @init({ { i8*, i8* }*, i8*}, i32) {
> entry:
>       %2 = tail call fastcc { { i8*, i8* }*, i8* } @init({ { i8*,
> i8*}*, i8*} %0, i32 %1)
>       ret { { i8*, i8* }*, i8*} %2
> }

I just noticed that altering my representation of the unit type also seems to 
break tail calls. Specifically, if I return the i1 or i8 types. Is that 
expected to break tail calls as well as returning structs? If so, when 
exactly can tail calls be relied upon?

Looks like i64 works fine on 32-bit, so it is not just non-word-sized values 
that are breaking it.

-- 
Dr Jon Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/?e