cmd/link: support DWARF compression on Darwin

We want to compress DWARF even on macOS, but the native toolchain isn't
going to understand it. Add a flag that can be used to disable
compression, then add Darwin to the whitelist used during internal
linking.

Unlike GNU ld, the Darwin linker doesn't have a handy linker flag to do
compression. But since we're already doing surgery to put the DWARF in
the output executable in the first place, compressing it at the same
time isn't unduly difficult. This does have the slightly odd effect of
compressing some Apple proprietary debug sections, which absolutely
nothing will understand. Leaving them uncompressed didn't make much
sense, though, since I doubt they're useful without (say) __debug_info.

Updates #11799

Change-Id: Ie00b0215c630a798c59d009a641e2d13f0e7ea01
Reviewed-on: https://go-review.googlesource.com/120155
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Heschi Kreinick 2018-06-20 16:45:25 -04:00
parent 3dced519cb
commit 726a2d04ea
5 changed files with 142 additions and 26 deletions

View file

@ -122,6 +122,7 @@ func Main(arch *sys.Arch, theArch Arch) {
flag.BoolVar(&ctxt.linkShared, "linkshared", false, "link against installed Go shared libraries")
flag.Var(&ctxt.LinkMode, "linkmode", "set link `mode`")
flag.Var(&ctxt.BuildMode, "buildmode", "set build `mode`")
flag.BoolVar(&ctxt.compressDWARF, "compressdwarf", true, "compress DWARF if possible")
objabi.Flagfn1("B", "add an ELF NT_GNU_BUILD_ID `note` when using ELF", addbuildinfo)
objabi.Flagfn1("L", "add specified `directory` to library path", func(a string) { Lflag(ctxt, a) })
objabi.AddVersionFlag() // -V