[Bug rtl-optimization/39837] [4.3/4.4/4.5 regression] extra spills due to RTL LICM

["steven at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #7 from steven at gcc dot gnu dot org  2010-01-29 23:11 -------
Created an attachment (id=19755)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=19755&action=view)
Hack to look for invariants inside MEMs

Re. comment #4:

The following code would also be correct, right?
test:
        push    {r4, lr}
        sub     sp, sp, #8
        mov     r3, #0
        add     r4, sp, #4
        str     r3, [sp, #4]
.L2:
        mov     r0, r4
        bl      func
        ldr     r3, [r4]
        cmp     r3, #12
        ble     .L2
        add     sp, sp, #8
        @ sp needed for prologue
        pop     {r4, pc}
        .size   test, .-test
        .ident  "GCC: (GNU) 4.5.0 20100129 (experimental) [trunk revision
156352]"

I have a really bad hack that makes loop-invariant look at addresses inside
MEMs (attached).
(Looking at Zdenek:) Would something like this in a more polished and actually
verified&tested form be a good idea?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39837