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tl;dr
How can I compile Ada source code to a static library file suitable for apps on iPad targets running iOS to link against? (GCC is not a requirement. Solutions using LLVM or others are also welcome!)

I have a large library of portable Ada code that I would like to use in an iPad/iOS project. My host OS is Mac OS X 10.9 (running GCC 4.8.1 installed at /opt/local with MacPorts). To do this, I'm trying to build a GCC ARM cross-compiler with Ada support.

I am able to build a working GCC and GNAT that creates ARM executables, but I can't seem to build or install the Ada standard library, which is required for building my Ada code

The source packages I'm using:

gcc-4.8.1
binutils-2.24
libiconv-1.14
gmp-5.1.3
mpc-1.0.2
mpfr-3.1.2

The GCC build configuration:

$ bin/arm-none-eabi-gcc -v --version
Using built-in specs.
COLLECT_GCC=bin/arm-none-eabi-gcc
COLLECT_LTO_WRAPPER=/Users/ardnew/cross/libexec/gcc/arm-none-eabi/4.8.1/lto-wrapper
arm-none-eabi-gcc (GCC) 4.8.1
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Target: arm-none-eabi
Configured with: /Users/ardnew/cross/src/gcc-4.8.1/configure --target=arm-none-eabi --prefix=/Users/ardnew/cross --with-cpu=cortex-a8 --enable-languages=c,ada --disable-multilib --enable-interwork --disable-threads --disable-shared --disable-nls --disable-lto --disable-libssp --disable-decimal-float --disable-libgomp --disable-libmudflap
Thread model: single
gcc version 4.8.1 (GCC)
COLLECT_GCC_OPTIONS='-v' '--version' '-mcpu=cortex-a8'
 /Users/ardnew/cross/libexec/gcc/arm-none-eabi/4.8.1/cc1 -quiet -v -D__USES_INITFINI__ help-dummy -quiet -dumpbase help-dummy -mcpu=cortex-a8 -auxbase help-dummy -version --version -o /var/folders/4c/y_sll7bj6b9bt15389wr66_80000gn/T//ccrSSKFx.s
GNU C (GCC) version 4.8.1 (arm-none-eabi)
  compiled by GNU C version 4.8.1, GMP version 5.1.3, MPFR version 3.1.2, MPC version 1.0.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
COLLECT_GCC_OPTIONS='-v' '--version' '-mcpu=cortex-a8'
 /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/bin/as -mcpu=cortex-a8 -meabi=5 --version -o /var/folders/4c/y_sll7bj6b9bt15389wr66_80000gn/T//ccZYvQLp.o /var/folders/4c/y_sll7bj6b9bt15389wr66_80000gn/T//ccrSSKFx.s
GNU assembler (GNU Binutils) 2.24
Copyright 2013 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `arm-none-eabi'.
COMPILER_PATH=/Users/ardnew/cross/libexec/gcc/arm-none-eabi/4.8.1/:/Users/ardnew/cross/libexec/gcc/arm-none-eabi/4.8.1/:/Users/ardnew/cross/libexec/gcc/arm-none-eabi/:/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/:/Users/ardnew/cross/lib/gcc/arm-none-eabi/:/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/bin/
LIBRARY_PATH=/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/:/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/lib/
COLLECT_GCC_OPTIONS='-v' '--version' '-mcpu=cortex-a8'
 /Users/ardnew/cross/libexec/gcc/arm-none-eabi/4.8.1/collect2 -X --version /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crti.o /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtbegin.o crt0.o -L/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1 -L/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/lib /var/folders/4c/y_sll7bj6b9bt15389wr66_80000gn/T//ccZYvQLp.o --start-group -lgcc -lc --end-group /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtend.o /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtn.o
collect2 version 4.8.1
/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/bin/ld -X --version /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crti.o /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtbegin.o crt0.o -L/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1 -L/Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/../../../../arm-none-eabi/lib /var/folders/4c/y_sll7bj6b9bt15389wr66_80000gn/T//ccZYvQLp.o --start-group -lgcc -lc --end-group /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtend.o /Users/ardnew/cross/lib/gcc/arm-none-eabi/4.8.1/crtn.o
GNU ld (GNU Binutils) 2.24
Copyright 2013 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

Test program to ensure its building ARM binaries:

$ cat told_unit1.adb told_unit1.ads

--
-- FILE: told_unit1.adb
--
with Ada.Text_IO;
use Ada.Text_IO;

package body told_unit1 is

  procedure hello is
  begin
    put_line("hello, world");
  end hello;

  function double(x : in float) return float is
  begin
    return x + x;
  end double;

end told_unit1;


--
-- FILE: told_unit1.ads
--
package told_unit1 is

  procedure hello;
  pragma Export
  (
    convention     =>  C,
    entity         =>  hello,
    external_name  =>  "ada_hello"
  );

  function double(x : in float) return float;
  pragma Export
  (
    convention     =>  C,
    entity         =>  double,
    external_name  =>  "ada_double"
  );

end told_unit1;

Then compiling the Ada code and inspecting it with file:

$ arm-none-eabi-gcc -c told_unit1.adb

$ file told_unit1.o
told_unit1.o: ELF 32-bit LSB relocatable, ARM, version 1 (SYSV), not stripped

And then when I try to bind the library object file it pukes:

$ arm-none-eabi-gnatbind -aO$ADA_OBJECT_PATH -Ltold told_unit1
error: "a-textio.ali" not found, "a-textio.adb" must be compiled

Going back to my GCC build logs, I found that libada (which I believe is part of GNAT) wasn't ever built. When I try to run make all-target-libada from the GCC build directory, it eventually tells me:

Configuring in arm-none-eabi/libada
configure: loading cache ./config.cache
checking build system type... x86_64-apple-darwin13.1.0
checking host system type... arm-none-eabi
checking target system type... arm-none-eabi
checking for arm-none-eabi-gcc...  /Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/xgcc -B/Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/ -B/Users/ardnew/cross/arm-none-eabi/bin/ -B/Users/ardnew/cross/arm-none-eabi/lib/ -isystem /Users/ardnew/cross/arm-none-eabi/include -isystem /Users/ardnew/cross/arm-none-eabi/sys-include
checking for C compiler default output file name...
configure: error: in `/Users/ardnew/cross/src/gcc-4.8.1-obj/arm-none-eabi/libada':
configure: error: C compiler cannot create executables
See `config.log' for more details.
make: *** [configure-target-libada] Error 1

And so I go inspect that config.log its referring to and find the following:

configure:2351: $? = 0
configure:2340:  /Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/xgcc -B/Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/ -B/Users/ardnew/cross/arm-none-eabi/bin/ -B/Users/ardnew/cross/arm-none-eabi/lib/ -isystem /Users/ardnew/cross/arm-none-eabi/include -isystem /Users/ardnew/cross/arm-none-eabi/sys-include    -v >&5
COLLECT_LTO_WRAPPER=/Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/lto-wrapper
Target: arm-none-eabi
Configured with: /Users/ardnew/cross/src/gcc-4.8.1/configure --target=arm-none-eabi --prefix=/Users/ardnew/cross --with-cpu=cortex-a8 --enable-languages=c,ada --disable-multilib --enable-interwork --disable-threads --disable-shared --disable-nls --disable-lto --disable-libssp --disable-decimal-float --disable-libgomp --disable-libmudflap
configure:2351: $? = 0
xgcc: error: unrecognized command line option '-qversion'
xgcc: fatal error: no input files
compilation terminated.
configure:2351: $? = 1
configure:2371: checking for C compiler default output file name
configure:2393:  /Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/xgcc -B/Users/ardnew/cross/src/gcc-4.8.1-obj/./gcc/ -B/Users/ardnew/cross/arm-none-eabi/bin/ -B/Users/ardnew/cross/arm-none-eabi/lib/ -isystem /Users/ardnew/cross/arm-none-eabi/include -isystem /Users/ardnew/cross/arm-none-eabi/sys-include    -g -O2   conftest.c  >&5
/Users/ardnew/cross/arm-none-eabi/bin/ld: cannot find crt0.o: No such file or directory
/Users/ardnew/cross/arm-none-eabi/bin/ld: cannot find -lg
/Users/ardnew/cross/arm-none-eabi/bin/ld: cannot find -lc
collect2: error: ld returned 1 exit status
configure:2397: $? = 1
configure:2434: result:
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME ""
| #define PACKAGE_TARNAME ""
| #define PACKAGE_VERSION ""
| #define PACKAGE_STRING ""
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL ""
| /* end confdefs.h.  */
|
| int
| main ()
| {
|
|   ;
|   return 0;
| }
configure:2440: error: in `/Users/ardnew/cross/src/gcc-4.8.1-obj/arm-none-eabi/libada':
configure:2444: error: C compiler cannot create executables
See `config.log' for more details.

So at this point I'm way over my head and not really sure what to do next. It looks like I'm missing a C runtime library for ARM maybe?

Any help configuring GNAT/libada for ARM targets would be great.

Alternatively- is there a simpler way to link against Ada libraries from an Xcode iOS project?

ardnew
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  • You should check whether you `arm-none-eabi` cross compiler is generating ELF or Macho binaries - the latter is required for both MacOSX, but I strongly suspect that configuration will produce ELF, which you can't use. This is not a huge problem, but you might need to build yourself a cross-compiling GCC and bin-utils with Mach-o support. – marko Apr 30 '14 at 22:51
  • @marko the `arm-none-eabi-gcc` is producing ELF bins (sorry for the wall of text, but check the code block I pasted 4th from the top), and you're saying the target iOS on a real, physical iPad is expecting Mach-O format and not ELF? if I change the format, i believe my current problem will still exist though – ardnew Apr 30 '14 at 23:11
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    Yes. ELF object files are no use to you on MacOSX or iOS as they use Mach-o object files and shared libraries only. THe ARM ABI is subtlety different as well. I would expect that a gcc targeted for ARM on iOS would have an arm `arm-apple-darwin-` prefix or something similar. Your errors may well be related to executable file format mismatch. – marko May 01 '14 at 12:37
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    There are some ada to C translators, another build path. – Gene May 07 '14 at 17:43
  • @marko the errors i'm seeing occur way before an iOS device is even brought into the picture. i'm unable to build libada for any arch different than the host's. getting the resulting executables to actually run on the iPad is not yet the problem. i will have my Macbook (the cross-compiler host) back tomorrow and try to demonstrate the problem for Mach-O bins as well – ardnew May 08 '14 at 04:11
  • @Gene thanks for the comment. we have paid for professional source code translation ([Mapusoft's Ada to C translator](http://www.mapusoft.com/ada-to-c-changer/)) in the past and have had serious problems with the translated type definitions and exception handling which required a lot of manual cleanup. additionally, this is a very large codebase that also requires security certifications. forking the project into 2 codebases requires twice the amount of certification required. source code translation isn't feasible for this project :( – ardnew May 08 '14 at 04:21

1 Answers1

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Unfortunately, the answer is that there is no auto-magic tool to accomplish this. You can use tooling to validate the translations after the fact, but what you want isn't available yet.

I've had to deal with this same question in the past. A different answer would have dramatically changed one of my project's budgets, too. Perhaps someday.

Though I admit, I think there are ultimately enough incompatibilities that your source would need to be drastically altered - reducing the value of what you are looking to achieve here. In the end, the new investment is a bummer but will result in better source, if you can afford it.

Jerry Nixon
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