[Bug target/50447] New: [avr] Better support of AND, OR, XOR and PLUS with constant integers for 16- and 32-bit values

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50447

             Bug #: 50447
           Summary: [avr] Better support of AND, OR, XOR and PLUS with
                    constant integers for 16- and 32-bit values
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: gjl@gcc.gnu.org
            Target: avr


The current implementation sometimes leads to poor code for several reasons:

o Insn "*iorsi3_clobber" is hidden behind "iorsi3" and thus will never
  be used.

o There are no such insn for AND, XOR, PLUS so that the constant gets 
  reloaded to a same-width register where a QI was sufficient.

o If a clobber is needed, the value in the clobber reg is not reused.

o Work out if a clobber is actually needed.