Prevent unsafe view-copy replacement around mutations

[JacobSzwejbka]

Summary

ReplaceViewCopyWithViewPass currently runs after reinplacement. A reinplaced mutation of the copied view can therefore become a mutation of the base after view_copy is changed to memory.view, even though the original copy kept the base unchanged. The inverse interaction is possible when the base is mutated while the copied view remains live.

Add a reusable is_copy_to_view_safe check that follows existing view aliases, schema-declared mutation aliases, and reinplace allocation-sharing annotations. It rejects a substitution only when a write to either prospective storage family precedes a read from the other family. Mutations after the other value's last read remain eligible for view replacement.

The helper accepts the set of existing aliasing operators so other copy-to-view passes, including slice-copy lowering, can share the same safety analysis.

Authored with Codex.

Test plan

• Added regression coverage for mutation through a view while its base remains live.
• Added regression coverage for mutation of the base while the view remains live.
• Added coverage showing both directions still replace the copy when the other value is dead.
• Ran the focused test_remove_view_copy cases and the existing test_replace_view_copy_with_view_pass case.
• Ran Black, Flake8, compileall, and git diff --check on the changed Python files.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/23279

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❌ 1 Unclassified Failure

As of commit 8674068 with merge base 21f770c ():

UNCLASSIFIED FAILURE - DrCI could not classify the following job because the workflow did not run on the merge base. The failure may be pre-existing on trunk or introduced by this PR:

• pull / test-arm-backend-vkml (test_runtime_vgf) / linux-job (gh) (this job did not run on the merge base, so DrCI cannot tell whether the failure is pre-existing)
  RuntimeError: Command docker exec -t bb9f6159c462fbf4f3973ebd76ef9989df278108ecdd7aa80fb84d19cf449dea /exec failed with exit code 1

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[metascroy]

LGTM!