[Tutorial][Binaries] gdc for android

[Andrew Wiley]

On Mon, Feb 6, 2012 at 1:40 AM, Johannes Pfau <nospam at example.com> wrote:
> Am Mon, 6 Feb 2012 03:07:31 +0200
> schrieb Manu <turkeyman at gmail.com>:
>
>> On 6 February 2012 02:25, Manu <turkeyman at gmail.com> wrote:
>>
>> > On 6 February 2012 00:04, Johannes Pfau <nospam at example.com> wrote:
>> >
>> >> Am Sun, 5 Feb 2012 18:04:12 +0100
>> >> schrieb Johannes Pfau <nospam at example.com>:
>> >>
>> >> > I will probably need some more time to get this working...
>> >> >
>> >>
>> >> I have some good news:
>> >> http://www.mediafire.com/?107we120sh3xx
>> >>
>> >> I fixed that problem and then the whole build worked fine. I'll
>> >> post build instructions soon, but the binaries are ready. I only
>> >> did a simple gdc -c test.d to check the compiler, but it seems to
>> >> work.
>> >>
>> >> Linking against druntime fails, as it uses functions which are not
>> >> available on Android (backtrace, signal stuff).
>> >>
>> >> I also built a simple hello world on linux (printf, no runtime)
>> >> and ran it on my android phone, and it worked!
>> >>
>> >> In case you haven't used GDC without runtime before, a short
>> >> introduction:
>> >>
>> >> * use gdc -nophoboslib to make gdc not link against phobos (and
>> >> afaik, druntime)
>> >> * theres also -nostdlib in case you need it
>> >> * complex code may require -fno-section-anchors because of bug #120
>> >> * You'll get an error about a missing _Dmodule_ref symbol. That
>> >> symbol is used by module constructors and not generated by gdc if
>> >>  -nophoboslib was passed. As long as you don't run the module
>> >>  constructors, you can add a fake _Dmodule_ref in a .c file:
>> >>
>> >> ------------
>> >> void* _Dmodule_ref;
>> >> ------------
>> >>
>> >> * The compiler defines version(Android)
>> >>
>> >> Here's my hello world:
>> >> ------------
>> >> version(Android)
>> >> {
>> >>    pragma(msg, "Hello Android!");
>> >> }
>> >>
>> >> extern(C)
>> >> {
>> >>    int printf(in char* format, ...);
>> >> }
>> >>
>> >> extern(C) void main()
>> >> {
>> >>    printf("Hello, %s!\n".ptr, "Android".ptr);
>> >> }
>> >> ------------
>> >>
>> >> compile the _Dmodule_ref into hack.o, then use
>> >> gdc -nophoboslib hello.d hack.o
>> >>
>> >
>> > Amazing! You sir, are a genius!
>> > I'm gonna have to have some fun with that after work tomorrow :)
>> >
>> > I reckon this binary distro should be put on d-p-l somewhere
>> > obvious.
>> >
>>
>> I just tried with -mfpu=neon, which should allow GCC to generate neon
>> opcodes for the simd stuff, but it didn't seem to want to do that. In
>> fact it generates really horrible code where it CALLS an intrinsic
>> for each float in the vector...
>> Any idea why this wouldn't work out of the box?
>
> The android toolchain configures gcc with: += --with-float=soft
> --with-fpu=vfp --with-arch=armv5te
>
> I could try to build an optimized build, but then you'll have to tell
> me what processor you're using. Cortex A8?
>
> I'm not sure if you can override that at runtime. You could probably
> try:
> -mfloat-abi=hard -mcpu=cortex-a8 -march=armv7-a -mfpu=neon

I'm pretty sure you have to rebuild the entire toolchain to switch
from softfloat to hardfloat.