cmd/link: need to handle new-style loong64 relocs

[abner-chenc]

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

$ go version
go version go1.21.3 linux/loong64

Does this issue reproduce with the latest release?

Yes (found during packaging testing)

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

Debian Linux sid, Loongson 3A5000.

go env Output

$ go env

What did you do?

cd $GOROOT/src/cmd/link && go test ./...

What did you expect to see?

all tests pass

What did you see instead?

ok  	cmd/internal/src	0.013s
ok  	cmd/internal/test2json	0.779s
--- FAIL: TestMinusRSymsWithSameName (0.76s)
    elf_test.go:164: gcc [-fPIC -mabi=lp64d -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4287643683=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName5512364/001/x0.o /tmp/TestMinusRSymsWithSameName5512364/001/x0.c
    elf_test.go:164: gcc [-fPIC -mabi=lp64d -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4287643683=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName5512364/001/x1.o /tmp/TestMinusRSymsWithSameName5512364/001/x1.c
    elf_test.go:172: gcc [-fPIC -mabi=lp64d -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4287643683=/tmp/go-build -gno-record-gcc-switches] -nostdlib -r -o /tmp/TestMinusRSymsWithSameName5512364/001/ldr.syso [/tmp/TestMinusRSymsWithSameName5512364/001/x0.o /tmp/TestMinusRSymsWithSameName5512364/001/x1.o]
    elf_test.go:192: /root/debian-upstream/golang-1.21-1.21.3/bin/go build
    elf_test.go:197: # elf_test
        /tmp/go-build2943499130/b001/_pkg_.a(ldr.syso): unknown relocation type 66; compiled without -fpic?
    elf_test.go:198: exit status 1
FAIL
FAIL	cmd/link	13.001s
ok  	cmd/link/internal/benchmark	0.023s

[gopherbot]

Change https://go.dev/cl/537615 mentions this issue: cmd/link/internal/loadelf: add additional relocations for loong64

[dr2chase]

@golang/compiler does this want a backport, perhaps? The change is small, and this looks like regression (though I am not sure).

[cherrymui]

Looks fine with me. Up to the Loong64 maintainers for whether this needs backport.

I think this is not a regression, just that Go 1.21 doesn't support newer C toolchains. To be clear, what version of the C toolchain do you use?

[gopherbot]

Change https://go.dev/cl/548478 mentions this issue: doc/go1.22: document addtional constants in debug/elf package

[abner-chenc]

@golang/compiler does this want a backport, perhaps? The change is small, and this looks like regression (though I am not sure).

This test failure has always existed on Go1.21. Can we backport this CL to the Go1.21 release-branch, @dr2chase
Thanks.

[cherrymui]

@gopherbot please backport this to Go 1.21. This causes test failures on the 1.21 release branch. Thanks.

[gopherbot]

Backport issue(s) opened: #67426 (for 1.21).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.