This file tracks the status of the merger of the
"Introduce rtx subclasses" patches, and is slated for removal once all
are merged.

See https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00498.html for more
information.

Phase 1: initial "scaffolding" commits:            DONE
Phase 2: per-file commits in main source dir:      DONE
Phase 3: per-file commits within "config" subdirs: DONE
Phase 4: removal of "scaffolding":                 DONE
Phase 5: additional rtx_def subclasses:            DONE
Phase 6: use extra rtx_def subclasses:             IN PROGRESS

TODO: "Scaffolding" to be removed
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* SET_NEXT_INSN, SET_PREV_INSN