[Bug middle-end/28690] [4.2 Regression] Performace problem with indexed load/stores on powerpc

["bergner at vnet dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from bergner at vnet dot ibm dot com  2006-10-03 03:30 -------
Created an attachment (id=12375)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12375&action=view)
Patch to swap_commutative_operands_p and gen_addr_rtx to force base pointers
into rA position of indexed load/store instructions.

We propagated the MEM_POINTER/REG_POINTER flags fine.  The problem is that the
memory reference we're handed is a REG + REG which looks legitimate to us, so
we never call LEGITIMIZE_ADDRESS, so we never have a chance to swap the
operands.

Since we cannot fixup the latest test case in LEGITIMIZE_ADDRESS, I've decided
to attempt another swap_commutative_operands_p() /
commutative_operand_precedence() change.  However, I'm a little more selective
on when we change swap_commutative_operands_p()'s return value.  With this
patch, I'm able to transform each of the test cases so that the base address if
the first operand of the indexed load.

        * rtlanal.c (swap_commutative_operands_p): Preference a REG_POINTER
        over a non REG_POINTER.
        * tree-ssa-address.c (gen_addr_rtx): Force a REG_POINTER to be
        the first operand of a PLUS.


-- 

bergner at vnet dot ibm dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #12305|0                           |1
        is obsolete|                            |
  Attachment #12306|0                           |1
        is obsolete|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28690