RFR: JDK-8217723 Switch ld from bfd to gold on gcc toolchain

[Martin Buchholz]

On Fri, Jan 25, 2019 at 10:07 AM Andrew Haley <aph at redhat.com> wrote:
>
> On 1/25/19 5:01 PM, Martin Buchholz wrote:
> > I re-ran my linker performance experiment using  configure
> > --with-native-debug-symbols="internal"
> > lld is a big winner here:
>
> It looks to me like lld and multi-threaded gold would be a near tie. I
> think that lld uses multi-threading; I wonder why gold doesn't. But
> either is so fast linking libjvm.so that I no longer care.

repeating my last experiment with explicit --threads:

--- ld=gold ---
/usr/bin/g++ -fuse-ld=$ld -Wl,--threads -Wl,--hash-style=both
-Wl,-z,defs      9.18s user 4.98s system 329% cpu 4.292 total
/usr/bin/g++ -fuse-ld=$ld -Wl,--threads -Wl,--hash-style=both
-Wl,-z,defs      9.12s user 5.12s system 333% cpu 4.266 total
--- ld=lld ---
/usr/bin/g++ -fuse-ld=$ld -Wl,--threads -Wl,--hash-style=both
-Wl,-z,defs      2.70s user 1.09s system 324% cpu 1.169 total
/usr/bin/g++ -fuse-ld=$ld -Wl,--threads -Wl,--hash-style=both
-Wl,-z,defs      2.74s user 1.00s system 328% cpu 1.141 total

and with explicit --no-threads:

--- ld=gold ---
/usr/bin/g++ -fuse-ld=$ld -Wl,--no-threads -Wl,--hash-style=both
-Wl,-z,defs   4.61s user 0.61s system 99% cpu 5.213 total
/usr/bin/g++ -fuse-ld=$ld -Wl,--no-threads -Wl,--hash-style=both
-Wl,-z,defs   4.60s user 0.61s system 99% cpu 5.212 total
--- ld=lld ---
/usr/bin/g++ -fuse-ld=$ld -Wl,--no-threads -Wl,--hash-style=both
-Wl,-z,defs   1.67s user 0.60s system 99% cpu 2.289 total
/usr/bin/g++ -fuse-ld=$ld -Wl,--no-threads -Wl,--hash-style=both
-Wl,-z,defs   1.66s user 0.60s system 99% cpu 2.283 total