[Bug rtl-optimization/64616] Redundant ldr when accessing var inside and outside a loop

[thopre01 at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64616

--- Comment #2 from thopre01 at gcc dot gnu.org ---
For arm-none-linux-gnueabihf-gcc configured with --with-arch=armv7-a and
compiling without any -mcpu (so default cpu) the problem is also there:

        stmfd   sp!, {r4, r5, r6, lr}
        movw    r5, #:lower16:glob
        movt    r5, #:upper16:glob
.L2:
        ldr     r0, [r5]
        movw    r4, #:lower16:glob
        bl      g
        movt    r4, #:upper16:glob
        cmp     r0, #0
        bne     .L2
        mov     r3, #1
        str     r3, [r4]
        ldmfd   sp!, {r4, r5, r6, pc}

This is due to pre introducing a new pseudoregister to load the address of glob
and cprop propagating it only locally in the same basic block but not globally
into the store.