[Bug middle-end/35141] ARM: Constant generation inside a loop: Missed optimization opportunity

["alexandre dot nunes at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from alexandre dot nunes at gmail dot com  2008-02-11 21:10 -------
(In reply to comment #2)
> Also using a volatile pointer may prevent optimization, so don't use it if
> not strictly needed (or at least don't expect optimized code).
> 
> Can you try 4.3 as suggested?
> 

Ok, PR35071 was the only blocker. I did a bad thing in order to bypass it (it
only affected a non-default [for me] target on my multilib config) and get the
whole thing to compile, and the result is:


whatever:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        ldrb    r3, [r0, #0]    @ zero_extendqisi2
        cmp     r3, #0
        bxeq    lr
        mov     r2, #-536870912
        add     r2, r2, #49152
.L3:
        str     r3, [r2, #0]
        ldrb    r3, [r0, #1]!   @ zero_extendqisi2
        cmp     r3, #0
        bne     .L3
        bx      lr


... which seems correct to me. (my build was from svn trunk, current date
20080211, unknow revision number [my build system got rid of .svn subdirs]).


No chance of a 4.2.x backport ? :-)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35141