[Bug target/34888] New: Stack patterns for AVR not optimal

["hutchinsonandy at aim dot com" <gcc-bugzilla at gcc dot gnu dot org>]

There are several instruction patterns related to stack pointer operations.
These are not quite right:

1) popqi and poph1 patterns use post_inc codes - when in fact there are pre_inc
 - this could fail if gcc ever used them outside prolog/epilog

2) Stack moves such as push/pop should be placed before mov patterns, to
provide best matching.

3)Stack adjustment (SP=SP+c) is matching with *addhi pattern, which causes
reloads of output and input. We really want it to match "*addhi3_sp_R_pc2" when
offset is small so *addhi3_sp_R_pc2 needs to be placed before *addhi

4)"*addhi3_sp_R_pc2" does not provide full range of optimal adjustment. For
example, SP=SP+8 takes 4 instructions using rcall but around 8 using addition
through register. This functionality needs extending accordingly as SP=SP+8 is
very common.


-- 
           Summary: Stack patterns for AVR not optimal
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hutchinsonandy at aim dot com
GCC target triplet: avr-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34888