> I never advocated eliminating undefined behavior from C, I advocate eliminating UB based "optimizations" from C compilers, particularly "optimizations" which

> I never advocated eliminating undefined behavior from C, I advocate eliminating UB based "optimizations" from C compilers, particularly "optimizations" which rely on assuming code will never do what emitted code does! OK, then that definition excludes register allocation as a permitted optimization. If you want to compile C code without any exploitation of undefined behavior, that's readily available! Just pass -O0 to your compiler.