This was done by adding --abort-on-invalid-reduction to remove-function-bodies-used-in-globals.ll and fixing the fallout.
Aliases must have a GlobalValue or ConstantExpr aliasee and the aliasee must be a definition if it's a GlobalValue.
Don't RAUW functions with null if there's an alias pointing to it, and similarly don't delete the body of a function.
Don't delete the entire body of a function when reducing blocks, preserve at least one block.
Also make debugging these sorts of things easier by dumping the module when --abort-on-invalid-reduction triggers.
Reviewed By: regehr
Differential Revision: https://reviews.llvm.org/D131505
Arthur Eubanks