* ssa.c (struct rename_set_data): Change the name of field
'set_dest' to 'old_reg'.  Add comments.
(struct rename_context): Change the name of 'set_data' to
'new_renames'.  Add new field 'done_renames'.
(create_delayed_rename): New function.
(apply_delayed_renames): New function.
(rename_insn_1): Use the new functions.  Handle CLOBBERS.  Handle
SUBREGs and similar by emitting a move.
(new_registers_for_updates): Delete, functionality moved to
apply_delayed_renames.
(rename_block): Handle moves emitted by rename_insn_1 by putting
them into a SEQUENCE with the original insn.  Add sanity checks
and comments.
(rename_equivalent_regs_in_insn): Don't handle SUBREGs specially.
(rename_equivalent_regs): Expand SEQUENCEs out to individual insns.

From-SVN: r34720