cmd/link: stop requiring gold on arm64 when GNU ld is fixed

[jcajka]

What version of Go are you using (go version)?

Any, more specifically 1.8, 1.9, master, most probably all versions supporting AArch64/arm64 target

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

linux/arm64

What did you do?

GC on linux/arm64 assumes gold linker availability see src/cmd/link/internal/ld/lib.go:1182
When gold is not available gcc fails due to it missing, when it tries to invoke it. All in shared_test.
When gold flag is remove by removing sys.ARM64 from codition on src/cmd/link/internal/ld/lib.go:1173, build/test fail with

--- FAIL: TestTrivialExecutable (0.29s)
	shared_test.go:66: executing go install -installsuffix=5577006791947779410 -linkshared trivial failed exit status 2:
		# trivial
		/root/go/pkg/tool/linux_arm64/link: running gcc failed: exit status 1
		/usr/bin/ld: /tmp/go-link-151650837/go.o(.data.rel.ro+0x2c0): unresolvable R_AARCH64_ABS64 relocation against symbol `go.link.abihash.libruntime,sync-atomic.so'
		/usr/bin/ld: final link failed: Nonrepresentable section on output
		collect2: error: ld returned 1 exit status

And so one for most of the cases shared_test.

What did you expect to see?

All tests pass. GC working with default binutils ld.

What did you see instead?

GC failing to build some binaries with binutils ld.

[ianlancetaylor]

For background see #15696 and https://sourceware.org/bugzilla/show_bug.cgi?id=19962. I think that we have to require gold until the GNU ld bug is fixed.

I'm going to close this issue since I don't see anything we can do. Please comment if you disagree.

[jcajka]

@ianlancetaylor AFAIK SWBZ is related only to ARM32, my issues is on ARM64. I could be easily wrong though or there is same issues on ARM64, I'm not that familiar with binutils\s ld code base.

Also I would like to keep this opened, even if this turns out to be fully binutils bug. As I think that the workaround code should be reverted when the issue is fixed in ld(whatever for ARM32/64 or both).

[ianlancetaylor]

OK, I guess.