ThinLTO on OS X!

[Johan Engelen via digitalmars-d-ldc]

On Tuesday, 27 September 2016 at 18:52:46 UTC, Johan Engelen 
wrote:
> Hi all,
>   The new XCode 8 features LLVM's ThinLTO in the linker. With 
> some patching in LDC, I got it to work pretty easily.

A brief update.

So there were a number of issues to be straightened out, some in 
LDC, some in LLVM, but now I think things are starting to look 
good for LTO :)

What is super cool is that when you have mixed C++/D source, and 
are using Clang/LDC, you get cross-language inlining with LTO! ^_^

<file b.cpp>
```
void doesNothing() {}
```

<file a.d>
```
extern(C++) void doesNothing(); // declaration only

void main() {
     for (ulong i = 0; i < 100_000_000; ++i) {
         doesNothing();
     }
}
```

The runtime is zero of the program when using `flto=thin` for 
both clang and LDC.
Without LTO, it takes a few seconds.

cheers,
   Johan