[Bug target/63223] New: [avr] Make jumptables work with -Wl,--section-start,.text=

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63223

            Bug ID: 63223
           Summary: [avr] Make jumptables work with
                    -Wl,--section-start,.text=
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gjl at gcc dot gnu.org

avr-gcc assumes that jumptables in section .progmem.gcc_sw_table are located in
the lower 64k of flash and uses LPM to read from these tables.

This does no more hold if the code is shifted to a higher address by, e.g.
-Wl,--section-start,.text=... which is commonly used with bootloadres.

This PR implements ELPM to access jumptables as needed.