I have heard that many optimizations that llvm can make are impossible in GCC. I barely grasp yacc, but I understand that a more cohesive design, less burdened

I have heard that many optimizations that llvm can make are impossible in GCC. I barely grasp yacc, but I understand that a more cohesive design, less burdened by history, can be greatly effective. There is a group that is trying to rework Linux in such a way that it can be compiled by llvm clang. I wish them the best.