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Re: Another bug in ARAnyM?

On 12/22/07, Wouter Verhelst <wouter@debian.org> wrote:
> On Sat, Dec 22, 2007 at 11:34:08AM +0300, Sergei Golovan wrote:
> >
> > Is this a bug in ARAnyM or it is a difference between m68k and other
> > architectures?
> This is definately not a bug in ARAnyM.
> On m68k, there are three sets of registers: the address registers (A0
> through A7), the data registers (D0 through D7), and the floating
> point registers (FP0 through FP7). The m68k ABI specifies that floating
> point return values should be stored in FP0, that integer return values
> should be stored in D0 (or split across D0 and D1 if it's a 64-bit
> value), and that pointers should be stored in A0.
> Your f() function returns a 32bit integer value, so it stores it in D0.
> However, your main() function thinks f() returns a pointer, so will look
> for a return value in A0. A0 does not have the value you're looking for,
> but something entirely different (it happens to be a constant value,
> probably some bits in libc use A0 at some point during its process
> initialization bits).

OK. Thanks for the info!

> In short, your code is doing stuff it shouldn't be doing.

I know that the code is incorrect. Though m68k seems to be the only
architecture where it doesn't work. I'm not sure I'll convince
upstream to rewrite the broken part (Erlang is hardly ever used on
m68k), but I'll certainly report this as a bug.

Sergei Golovan

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