There are several variations of the T32 libraries. It depends on the architecture target or processor as to which one is used.
Arm®v7‑A and Armv7‑R use a T32 library. It contains a small number of A32 instructions that are used to significantly improve performance.
Armv7‑M, Armv7E-M, and Armv8‑M.mainline have their own T32 library.
Armv6‑M and Armv8‑M.baseline have their own T32 library.