tm.texi: Document TARGET_DWARF_REGISTER_SPAN.

tm.texi: Document TARGET_DWARF_REGISTER_SPAN.

2003-03-05  Aldy Hernandez  <aldyh@redhat.com>

        * doc/tm.texi: Document TARGET_DWARF_REGISTER_SPAN.

        * config/rs6000/rs6000.c (rs6000_dwarf_register_span): New.

        * hooks.c (hook_rtx_rtx_null): New.

        * hooks.h (hook_rtx_rtx_null): Protoize.

        * target-def.h (TARGET_DWARF_REGISTER_SPAN): New macro.
        (TARGET_INITIALIZER): Add TARGET_DWARF_REGISTER_SPAN.

        * target.h (struct gcc_target): Add dwarf_register_span.

        * dwarf2out.c (multiple_reg_loc_descriptor): New.
        (one_reg_loc_descriptor): New.
        (reg_loc_descriptor): Add support for values that span more than
        one register.

From-SVN: r63870