Moritz Angermann authored Mar 21, 2017 and Ben Gamari committed Mar 26, 2017

This is the final commit that ties them all together. Here we
add the aarch64 linker for macho files.

- In D3238 we started allowing preloading object code with mmap
  in iOS, where we can't have r+w+x.
- In D3239 we introduced a richer extension of the object code
  data type to make working with mach-o files easier.
- In D3240 we set the stage to allow loading archives (.a) on iOS
- In D3251 we added init and deinit functions to populate and
  depopulate the enriched object code data structure for mach-o
  files.
- In D3252 we refactored most of the MachO.c file to use the
  new types and datastructure.

This commit will than finally add the aarch64 (arm64) linker
for mach-o files to ghc, using the improved foundation we
have constructed above.

The dependency structure therefore is as follows

```
  .- D3240
  v
This <- D3252 <- D3251 <- D3239
  ^
  '- D3238
```

Depends: D3252, D3240, D3238

Test Plan:
To test this with iOS, we also need the remote-iserv
diff D3233. With all that in place, proceed as follows:

- Build ghc for the host

```
  ghc $ ./configure --prefix=/test/opt \
    --disable-large-address-space \
    --with-llc=/path/to/llvm-3.9/bin/llc \
    --with-opt=/path/to/llvm-3.9/bin/opt
  # edit mk/build.mk to specify quick
  ghc $ make && make install
```

- Build ghc for ios

```
  ghc $ ./configure --target=aarch64-apple-darwin14 \
    --prefix=/test/opt \
    --disable-large-address-space \
    --with-llc=/path/to/llvm-3.9/bin/llc \
    --with-opt=/path/to/llvm-3.9/bin/opt \
    --with-ghc=/test/bin/ghc \
    --enable-bootstrap-with-devel-snapshot
  # edit mk/build.mk to specify quick-cross
  ghc $ make && make install

```
- Obtain the iOS wrapper scripts from
https://github.com/angerman/ghc-ios-scripts
  and place them in PATH.

- Build iserv-proxy for the host

```
  ghc/iserv $ cabal install -fproxy -flibrary

```
- Build iserv-library for the target

```
  # build cryptonite without integer-gmp
  ghc/iserv $ aarch64-apple-darwin14-cabal install cryptonite
-f-integer-gmp
  ghc/iserv $ aarch64-apple-darwin14-cabal install -flibrary
```

- Create an iOS application with the following `main.m`:
```
  #import <UIKit/UIKit.h>
  #include "HsFFI.h"
  extern void startSlave(bool, int, const char *);

  int main(int argc, char * argv[]) {
    const char * documents_path = [[[NSFileManager defaultManager]
URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask]
firstObject].path.UTF8String;

    hs_init(NULL, NULL);

    startSlave(false, 5000, documents_path);

    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, nil);
    }
  }
```

  and link it with: the iserv archive from
`~/.cabal/lib/aarch64-ios-ghc`
  as well as all dependent archives.

- Build, Install and Launch the iserv-slave application on your iphone

- Compile some Template Haskell code with the
`aarch64-apple-darwin14-ghc`,
  through the `iserv-proxy`

```
  app $ aarch64-apple-darwin14-ghc Module.hs \
   -threaded -staticlib \
   -outputdir build/aarch64 -pgmlibtool libtool-quiet -stubdir . \
   -fexternal-interpreter \
   -pgmi=$HOME/.cabal/bin/iserv-proxy \
   -opti10.0.0.1 \
   -opti5000
```
  where 10.0.0.1 is the ip of your iserv-slave.

  magic.

Reviewers: rwbarton, bgamari, austin, hvr, erikd, simonmar

Subscribers: thomie, erikd, ryantrinkle

Differential Revision: https://phabricator.haskell.org/D3255