dwarf2out: Move insn scanning out of final.c.

dwarf2out: Move insn scanning out of final.c.

This patch is essentially Bernd's 005-scanfirst patch, updated for
the introduction of the dwarf2cfi.c file.

We introduce NOTE_INSN_CFI and NOTE_INSN_CFI_LABEL to hold the dwarf2
info during the bulk of final.  The actual construction of these notes
still happens during final, right at the very beginning of the pass,
via the dwarf2out_frame_debug_init hook.

        * dwarf2cfi.c (cfi_insn): New.
        (dwarf2out_cfi_label): Don't emit cfi label here.
        (add_fde_cfi): Create a NOTE_INSN_CFI.
        (dwarf2out_frame_debug): Setup cfi_insn.
        (dwarf2out_frame_debug_init): Loop over insns creating CFI notes.
        (dwarf2out_cfi_begin_epilogue): Make static.
        (dwarf2out_frame_debug_restore_state): Make static.
        * dwarf2out.c (output_cfi_directive): Make static.
        (dwarf2out_emit_cfi): New.
        * dwarf2out.h: Update.
        * final.c (final): Remove CFI notes.
        (final_scan_insn): Don't call dwarf2out_cfi_begin_epilogue,
        dwarf2out_frame_debug_restore_state, dwarf2out_frame_debug.
        Handle NOTE_INSN_CFI and NOTE_INSN_CFI_LABEL.
        * insn-notes.def (NOTE_INSN_CFI): New.
        (NOTE_INSN_CFI_LABEL): New.
        * rtl.h (union rtunion_def): Add rt_cfi member.
        (XCFI, XCCFI, NOTE_CFI, NOTE_LABEL_NUMBER): New.

Co-Authored-By: Richard Henderson <rth@redhat.com>
From-SVN: r176016