Linker errors on test-linux action

[targos]

I thought it was due to missing includes so I added some in 3d0e2ae, but the errors remain:

https://github.com/nodejs/node-v8/actions/runs/10788009205/job/29917856466

2024-09-10T09:32:08.5123584Z /usr/bin/ld: /home/runner/work/node-v8/node-v8/out/Release/obj.target/v8_base_without_compiler/deps/v8/src/execution/isolate.o: in function `v8::internal::Isolate::~Isolate()':
2024-09-10T09:32:08.5125580Z isolate.cc:(.text._ZN2v88internal7IsolateD2Ev+0x3ff): undefined reference to `__atomic_compare_exchange'
2024-09-10T09:32:08.5126892Z /usr/bin/ld: isolate.cc:(.text._ZN2v88internal7IsolateD2Ev+0x4df): undefined reference to `__atomic_compare_exchange'
2024-09-10T09:32:08.5129081Z /usr/bin/ld: isolate.cc:(.text._ZN2v88internal7IsolateD2Ev+0x5bf): undefined reference to `__atomic_compare_exchange'
2024-09-10T09:32:08.5131627Z /usr/bin/ld: /home/runner/work/node-v8/node-v8/out/Release/obj.target/v8_base_without_compiler/deps/v8/src/execution/isolate.o: in function `v8::internal::wasm::WasmCodePointerTable::AllocateUninitializedEntry()':
2024-09-10T09:32:08.5134385Z isolate.cc:(.text._ZN2v88internal4wasm20WasmCodePointerTable26AllocateUninitializedEntryEv[_ZN2v88internal4wasm20WasmCodePointerTable26AllocateUninitializedEntryEv]+0x4b): undefined reference to `__atomic_compare_exchange'
2024-09-10T09:32:08.5137023Z /usr/bin/ld: isolate.cc:(.text._ZN2v88internal4wasm20WasmCodePointerTable26AllocateUninitializedEntryEv[_ZN2v88internal4wasm20WasmCodePointerTable26AllocateUninitializedEntryEv]+0x12e): undefined reference to `__atomic_compare_exchange'
2024-09-10T09:32:08.6131002Z /usr/bin/ld: /home/runner/work/node-v8/node-v8/out/Release/obj.target/v8_base_without_compiler/deps/v8/src/wasm/wasm-code-manager.o:wasm-code-manager.cc:(.text._ZN2v88internal4wasm8WasmCodeD2Ev+0xab): more undefined references to `__atomic_compare_exchange' follow
2024-09-10T09:32:09.2511911Z clang++: error: linker command failed with exit code 1 (use -v to see invocation)
2024-09-10T09:32:09.2553728Z make[2]: *** [tools/v8_gypfiles/mksnapshot.target.mk:220: /home/runner/work/node-v8/node-v8/out/Release/mksnapshot] Error 1

[richardlau]

undefined reference to `__atomic_compare_exchange'

Perhaps the version of clang being used in Actions requires to be linked against libatomic?

[lemire]

The following reference seems relevant:

https://clang.llvm.org/docs/Toolchain.html#libatomic-gnu

I think @richardlau is correct, here is what LLVM docs say:

You may need to manually add -latomic

[richardlau]

tools/v8_gypfiles/v8.gyp links to atomic on some architectures (but not x64):

        # Platforms that don't have Compare-And-Swap (CAS) support need to link atomic library
        # to implement atomic memory access
        ['v8_current_cpu in ["mips64", "mips64el", "ppc", "arm", "riscv64", "loong64"]', {
          'link_settings': {
            'libraries': ['-latomic', ],
          },
        }],

node.gyp sets for target_defaults:

      ['OS=="linux" and clang==1', {
        'libraries': ['-latomic'],
      }],

(I wonder if libraries here needs to be inside a link_settings?)

[targos]

My main concern is: why is it suddenly a problem?
If it's related to host updates on GitHub Actions, why do we only have this with canary?

[richardlau]

I can only assume something has changed in V8 13.0 compared to 12.9. The stack from the linker in the description is suggesting that it's coming from v8::internal::Isolate::~Isolate() calling into WasmCodePointerTable, which looks to be v8/v8@2166490#diff-76761d277cce95bd9f0a3f0d836f94f36bfbd32b1026c247faf32acbcd67a625

WasmCodePointerTable looks to be new, introduced in v8/v8@0b1d09b.

[targos]

This code is new, but not the fact that V8 depends on atomics?

[targos]

After reading https://clang.llvm.org/docs/Toolchain.html#libatomic-gnu, I understand that Clang apparently does not always require -latomic.
I'm trying to fix this in nodejs/node#55014 (nodejs/node@d48a069)

[targos]

Build looks good. I'm adding the commit to canary-base