Repository: nodejs/node
Pull request: build: aix: deoptimise implementation-visitor to avoid segfault

When building node.js with `--shared` on AIX the `torque` execution consistently fails with a segmentation fault. This has been tracked down by a change in the v20 timeframe when [V8 was updated to 11.3.244.4](https://github.com/nodejs/node/pull/47251) but at an initial cursory glance it's not immediately clear which change caused it.

By experimentation (by other teams I have spoken to and extra work by myself) it has also been observed that dropping the optimisation level from `-O3` to `-O1` on one source file reliably prevents the crash from occurring. Just to be clear, this problem does not occur on the non-shared library build therefore this change reduces the optimisation only for the shared build and only on AIX.

It is hoped that with this change we can reactivate the [node-test-commit-aix-shared-lib](https://ci.nodejs.org/job/node-test-commit-aix-shared-lib) job and maybe even add in the additional testing being proposed under https://github.com/nodejs/node/pull/61463 in the future.

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Changed files:
filename: tools/v8_gypfiles/v8.gyp
patch: @@ -1429,6 +1429,15 @@
           'ExceptionHandling': 1,
         },
       },
+      # Reduce optimisation of one file on AIX - it causes torque
+      # to segfault if you build node with "--shared"
+      'conditions': [
+        ['OS=="aix" and node_shared=="true"', {
+          'cflags': ['-O1'],
+          'cflags!': ['-O3'],
+          'sources': ['<(V8_ROOT)/src/torque/implementation-visitor.cc'],
+        }],
+      ],
     },  # torque_base
     {
       'target_name': 'torque_ls_base',