Comment 12 for bug 705689

Test code on maverick (no explicate it block):

mcasadevall@risingsun:/srv/chroots/maverick-armel$ cat test.c
#include <stdio.h>

int _q_value = 10;

inline bool testAndSetOrdered(int expectedValue, int newValue)
{
    register int result;
    asm volatile("0:\n"
                 "ldrex %[result], [%[_q_value]]\n"
                 "eors %[result], %[result], %[expectedValue]\n"
                 "strexeq %[result], %[newValue], [%[_q_value]]\n"
                 "teqeq %[result], #1\n"
                 "beq 0b\n"
                 : [result] "=&r" (result),
                   "+m" (_q_value)
                 : [expectedValue] "r" (expectedValue),
                   [newValue] "r" (newValue),
                   [_q_value] "r" (&_q_value)
                 : "cc", "memory");
    return result == 0;
}

int main() {
        return testAndSetOrdered(1, 1);
}

Relevant disassembly from objdump:

00008378 <_Z17testAndSetOrderedii>:
    8378: b490 push {r4, r7}
    837a: b082 sub sp, #8
    837c: af00 add r7, sp, #0
    837e: 6078 str r0, [r7, #4]
    8380: 6039 str r1, [r7, #0]
    8382: f241 0124 movw r1, #4132 ; 0x1024
    8386: f2c0 0101 movt r1, #1
    838a: 6878 ldr r0, [r7, #4]
    838c: f8d7 c000 ldr.w ip, [r7]
    8390: f241 0324 movw r3, #4132 ; 0x1024
    8394: f2c0 0301 movt r3, #1
    8398: f241 0224 movw r2, #4132 ; 0x1024
    839c: f2c0 0201 movt r2, #1
    83a0: e853 4f00 ldrex r4, [r3]
    83a4: 4044 eors r4, r0
    83a6: bf02 ittt eq
    83a8: e843 c400 strexeq r4, ip, [r3]
    83ac: f094 0f01 teqeq r4, #1
    83b0: e7f6 beq.n 83a0 <_Z17testAndSetOrderedii+0x28>
    83b2: 2c00 cmp r4, #0
    83b4: bf14 ite ne
    83b6: 2300 movne r3, #0
    83b8: 2301 moveq r3, #1
    83ba: b2db uxtb r3, r3
    83bc: 4618 mov r0, r3
    83be: f107 0708 add.w r7, r7, #8
    83c2: 46bd mov sp, r7
    83c4: bc90 pop {r4, r7}
    83c6: 4770 bx lr