Re: Compilation time

Evan Laforge writes:

On Fri, Jul 7, 2017 at 9:28 AM, Ben Gamari wrote:

...

In short, ./configure will now choose to use ld.gold or ld.lld if available (although this can be disabled using the --disable-ld-override configure flag).

Just from curiosity, does this apply to OS X? Of course, gold is ELF-only, so it surely doesn't apply, but there's still lld. OS X uses clang to compile so I thought it might already use lld, but the 'ld -v' output looks different, and lld.llvm.org implies it's a replacement for OS X ld, so maybe not. But it doesn't look like GNU ld either, so maybe it's not affected by the BFD bug?

I'll try 8.2 on OS X and see if the link time changes.

8.2 will prefer both gold and lld over bfd ld. However two conditions must hold for these to be used, * The ld.lld/ld.gold executable must be in $PATH (or explicitly named by passing the LD variable to configure) * $CC must understand the `-fuse-ld={gold,lld}` option. For (IMHO quite silly) political reasons, gcc doesn't support `-fuse-ld=lld`. Debian happens to patch gcc to add support but I don't know how common this is in other distributions. Unfortunately, some earlier `gcc` versions didn't fail if given a `-fuse-ld` option that they didn't understand. Sadly we have no reliable way to detect this, so in this case we may end up passing a `-fuse-ld` option that gcc simply ignores. In the case of OS X we use Apple's own home-grown linker. I'm not sure whether/how OS X's gcc wrapper treats `-fuse-ld` (beyond that it doesn't error if the flag is given). I also don't know whether lld is currently a capable replacement for OS X ld. Cheers, - Ben