llvm::MachineSSAUpdater::RewriteUse

RewriteUse ‐ Rewrite a use of the symbolic value. This handles PHI nodes, which use their value in the corresponding predecessor. Note that this will not work if the use is supposed to be rewritten to a value defined in the same block as the use, but above it. Any 'AddAvailableValue's added for the use's block will be considered to be below it.