[Bug target/27016] [4.3/4.4/4.5 Regression] ARM optimizer produces severely suboptimal code

[steven at gcc dot gnu dot org]

------- Comment #7 from steven at gcc dot gnu dot org  2010-02-12 22:52 -------
If arm_arm_address_cost is "fixed" to return 1 unconditionally, the expected
code of comment #5 comes out at -Os, with the bonus of one less branch:

testme:
        ldr     r2, .L4
        ldr     r1, .L4+4
        sub     r3, r2, #400
.L2:
        ldr     r0, [r1], #4
        str     r0, [r3], #4
        cmp     r3, r2
        bne     .L2
        bx      lr

This is actually a regression from GCC 3.4.6.


-- 

steven at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rearnsha at gcc dot gnu dot
                   |                            |org
          Component|middle-end                  |target
 GCC target triplet|arm-elf-unknown             |arm-elf, arm-eabi
      Known to fail|                            |4.4.0 4.5.0
      Known to work|                            |3.4.6
            Summary|ARM optimizer produces      |[4.3/4.4/4.5 Regression] ARM
                   |severely suboptimal code    |optimizer produces severely
                   |                            |suboptimal code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27016