[AllocToken] Introduce llvm.alloc.token.id intrinsic (#163632)

Introduce a new intrinsic, `llvm.alloc.token.id`, to allow compile-time
querying of allocation token IDs.

The `AllocToken` pass is taught to recognize and lower this intrinsic.
It extracts the `!alloc_token` metadata from the intrinsic's argument,
feeds it into the same token-generation logic used for instrumenting allocation
calls, and replaces the intrinsic with the resulting constant integer token ID.

This is a prerequisite for `__builtin_infer_alloc_token`. The pass now
runs on all functions to ensure intrinsics are lowered, but continues to
only instrument allocation calls in functions with the
`sanitize_alloc_token` attribute.

0 files changed, 0 insertions, 0 deletions