ARM support

[Johannes Pfau]

Am Fri, 10 Jan 2014 08:27:37 +0000
schrieb "Joakim" <joakim at airpost.net>:

> On Thursday, 9 January 2014 at 18:07:16 UTC, Piotr Szturmaj wrote:
> > Hello,
> >
> > I'm developing embedded system product on ARM9/Linux platform 
> > and I wish I could use D and vibe.d for this task.
> >
> > I have couple of questions in this matter:
> Like Mike, I'm an interested user, who wants to see D on ARMv7, 
> not a core developer, but I'll take a shot at answering your 
> questions.
> 
> > - What is the current status of ARM support?
> Limited.  The reference DMD compiler has no support for ARM, 
> while the LDC and GDC compilers are trying to utilize the ARM 
> backends of llvm and gcc to add ARM support, as Mike points out, 
> but they're not finished.  Not sure where ARM9 specifically fits 
> into all this.

The exact ARM architecture version doesn't matter that much. I mainly
test ARMv5 and ARMv6 older versions are untested. But OS support does
matter, I only work on Linux/GLIBC systems right now.


> > - Does druntime support ARM plaforms?
> Grepping through the code, druntime appears to use a fair amount 
> of x86 assembly, but I have not yet looked into how much of that 
> is optimization and therefore not strictly necessary to 
> reimplement on ARM.

You'll have to look at GDC/LDC druntime and not the DMD druntime to
see the ARM stuff. GDC/LDC specific stuff is not being upstreamed.
There's some ARM asm in GDC:druntime, but we try to rewrite all DMD
asm in terms of cross-platform GCC builtins (__builtin_trap instead of
asm{int 3;} and so on) so there's really not much ASM left for
GDC:druntime. 


> > - Does GC run reliably on ARM (or is it platform independent)?
> I don't think anybody can know for sure, since nobody has tried 
> to make it work.  The source appears to be fairly independent, 
> but other core features like threading or fibers appear not be.

The GC works just fine for GDC/ARM. See my other reply for details.
Threading is portable as long as you're on Posix, Fibers in theory as
well (there is a backend using posix libc functions and that works fine
on ARM. But only recent glibc version > 2.17 implement these functions)