> I think it's valuable to have a separate C module for optimizations, instead of cramming them in compiler.c.

This would require major rewriting. PR 5077 adds just two functions in compile.c. But they use 4 structures defined locally in this file. If move these two functions in a separate file we will need to move these 4 structures and related definitions to the common header file. And maybe it will be in vain if once all these optimizations will be moved to other parts of the compiler. Some of jumps optimization already are performed on instructions emitting stage. Dead code elimination perhaps could be performed at the stage of assembling the bytecode from basic blocks. Constant tuples folding could be implemented by at least three ways besides the current implementation, I'm testing what of them is the simplest.