I'm wondering, since Mojo doesn't use most of MLIR's built-in dialects(only LLVM+Index), will upstream improvements to optimization passes for these dialects no

I'm wondering, since Mojo doesn't use most of MLIR's built-in dialects(only LLVM+Index), will upstream improvements to optimization passes for these dialects not be immediately applicable? (Mojo uses its own custom MLIR dialect)