[ORCJIT] Reinject contexts on first function lookup

[tqchen]

Summary

• defer context injection from empty-library construction to the first ordinary function lookup
• cache each successful refresh; after LLVM accepts an object, AddObjectFile publishes the refresh flag as false
• keep AddObjectFile outside the thread-safety contract: it must not race GetFunction, and a failed add naturally leaves the prior flag unchanged
• keep concurrent GetFunction calls thread-safe with an acquire fast path and a mutex-protected, double-checked refresh on the false path, followed by one ordinary symbol lookup
• preserve ordinary GetSymbol initializer execution and LLVM error propagation
• keep the ORCJIT wheel test environment aligned with the repository-wide parallel pytest configuration by installing pytest-xdist
• bump the addon package to 0.1.1

If callers violate the AddObjectFile/GetFunction contract, LLVM may expose a newly added symbol and GetFunction may return its stable allocated address before that object's context slots are refreshed. The symbol remains visible, but context initialization is not guaranteed for that unsupported overlap.

Regression

One C object defines only __tvm_ffi__library_ctx and a probe. Barrier-synchronized first lookups verify that every returned function observes the injected pointer without adding another fixture.

Validation

• GCC- and Clang-built addon suites: 139 passed, 3 platform skips each
• fresh CI-equivalent wheel environment with local root package, default parallel pytest, and C/C++ quick starts
• 200 rounds with eight concurrent first GetFunction callers after object addition
• focused context, invalid-object, constructor, and destructor tests
• fresh 0.1.1 wheel build, isolated install, focused regression, and quick starts
• applicable formatting and lint hooks

[gemini-code-assist]

Code Review

This pull request defers the initialization of library context symbols in the ORC JIT compiler to the first function lookup after an object file is added, rather than performing it immediately in the constructor. It also updates error handling in symbol resolution and adds corresponding tests. The reviewer feedback correctly identifies that the newly introduced state variable context_symbol_refreshed_ is accessed and modified concurrently without synchronization, which can lead to data races. Introducing a mutex to protect this state is highly recommended to ensure thread safety.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.