[Bug target/50931] New: [avr] Support a 24-bit scalar integer mode

["gjl at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50931

             Bug #: 50931
           Summary: [avr] Support a 24-bit scalar integer mode
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: target
        AssignedTo: gjl@gcc.gnu.org
        ReportedBy: gjl@gcc.gnu.org
                CC: eric.weddington@atmel.com
            Target: avr


In order to support the upcoming named address spaces, a 24-bit wide mode is
needed because 32-bit mode is too expensive.

As a byproduct, 24-bit arithmetic can be exposed to user for general integer
arithmetic by means of built-in types. This is advantageous if 32-bit
arithmetic is too expensive and 16-bit arithmetic is too unprecise.