Fix load/store barriers in pre-ARMv7 builds

As pointed out in #10244 (closed) and D894, the fix we committed for this problem isn't 100% correct - from 753b156d:

#elif arm_HOST_ARCH && defined(arm_HOST_ARCH_PRE_ARMv7)
    // TODO FIXME: This case probably isn't totally correct - just because we
    // use a pre-ARMv7 toolchain (e.g. to target an old Android device), doesn't
    // mean the binary won't run on a newer ARMv7 system - in which case it
    // needs a proper barrier. So we should rethink this
    //  - Reid
    __asm__ __volatile__ ("" : : : "memory");

This is a reminder to fix this.

Trac metadata

Trac field	Value
Version
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	simonmar
Operating system
Architecture