Hi!

This patch generates Thumb2 epilogues in RTL form.

The work involves defining new functions, predicates and patterns along with
few changes in existing code:
* The load_multiple_operation predicate was found to be too restrictive for
integer loads as it required consecutive destination regs, so this
restriction was lifted.
* Variations of load_multiple_operation were required to handle cases 
   - where SP must be the base register 
   - where FP values were being loaded (which do require consecutive
destination registers)
   - where PC can be in register-list (which requires return pattern along
with register loads).
  Hence, the common code was factored out into a new function in arm.c and
parameterised to show 
   - whether consecutive destination regs are needed
   - the data type being loaded 
   - whether the base register has to be SP
   - whether PC is in register-list

The patch is tested with arm-eabi with no regressions.

ChangeLog:

2011-09-28  Ian Bolton         <ian.bolton@arm.com>
            Sameera Deshpande  <sameera.deshpande@arm.com>
           
       * config/arm/arm-protos.h (load_multiple_operation_p): New
declaration.
         (thumb2_expand_epilogue): Likewise.
         (thumb2_output_return): Likewise
         (thumb2_expand_return): Likewise.
         (thumb_unexpanded_epilogue): Rename to... 
         (thumb1_unexpanded_epilogue): ...this 
       * config/arm/arm.c (load_multiple_operation_p): New function. 
         (thumb2_emit_multi_reg_pop): Likewise.
         (thumb2_emit_vfp_multi_reg_pop): Likewise.
         (thumb2_expand_return): Likewise. 
         (thumb2_expand_epilogue): Likewise. 
         (thumb2_output_return): Likewise
         (thumb_unexpanded_epilogue): Rename to...
         ( thumb1_unexpanded_epilogue): ...this
       * config/arm/arm.md (pop_multiple_with_stack_update): New pattern. 
         (pop_multiple_with_stack_update_and_return): Likewise.
         (thumb2_ldr_with_return): Likewise.
         (floating_point_pop_multiple_with_stack_update): Likewise.
         (return): Update condition and code for pattern.
         (arm_return): Likewise.
         (epilogue_insns): Likewise.
       * config/arm/predicates.md (load_multiple_operation): Update
predicate.
         (load_multiple_operation_stack_and_return): New predicate. 
         (load_multiple_operation_stack): Likewise.
         (load_multiple_operation_stack_fp): Likewise.
       * config/arm/thumb2.md (thumb2_return): Remove.
         (thumb2_rtl_epilogue_return): New pattern.


- Thanks and regards,
  Sameera D.