Library compcertx.backend.ConstpropX

Require compcert.backend.Constprop.
Require ValueDomainX.

Import AST.
Import ValueDomainX.
Export Constprop.

Here we define per-function/module constant propagation, without any proof.
As said in ValueDomainX, we do not consider any optimization on `const' global variables, so the read-only memory abstraction will be empty.