* dwarf2out.c (expand_builtin_init_dwarf_reg_sizes): Honor
        DWARF_ALT_FRAME_RETURN_COLUMN.
        * unwind-dw2.c (dwarf_reg_size_table): Expand by one.
        (_Unwind_GetGR, _Unwind_SetGR): Validate lookup column.
        (uw_frame_state_for): Return end-of-stack for null return address.
        * doc/tm.texi (DWARF_ALT_FRAME_RETURN_COLUMN): Add.

        * config/alpha/alpha.c (alpha_sa_mask): Add r31 for eh_return.
        (alpha_expand_prologue): Store a zero for it.
        (alpha_expand_epilogue): Don't reload it.
        * config/alpha/alpha.h (DWARF_ALT_FRAME_RETURN_COLUMN): New.
        * config/alpha/linux.h (MD_FALLBACK_FRAME_STATE_FOR): Use column 64
        for the sigframe return address.

From-SVN: r71967