[compiler-rt] Sanitizer/MIPS: Use $t9 for preemptible function call (PR #76894)

[YunQiang Su via llvm-commits]

wzssyqa wrote:

@MaskRay Thanks for your note. I find a new problem: R6 also need t9 due to that the existing libraries depends on $t9.

https://github.com/llvm/llvm-project/pull/76894