Where %clang and %clang_cc1 defined.

In test case, we write “RUN: %clang …” or “RUN:%clang_cc1 …”. Could anyone tell me where %clang and %clang_cc1 are defined?

I think in the 'llvm-lit' tool.

Quick search points to: llvm/utils/lit/lit/llvm/config.py
Line 410 for clang_cc1.