extra_ops.hpp: adapt to AIX assembler

[Helflym]

AIX assembler doesn't allow "bne- 1b" to jump to the previous label "1".
It must be replaced by "bne- $N", N being the memory offset between
the current instruction and the targeted label.

[Lastique]

As a general comment, I would prefer to avoid #ifdefs all over the code and instead use macros to expand to either labels or offsets.

[Helflym]

Yes, that would be better indeed. I see if I can do that.
By the way, do you know why I don't need to modify "core_arch_ops" header too ? It doesn't seem to be used by "atomic" tests on AIX, but I'm not sure why.

[Lastique]

By the way, do you know why I don't need to modify "core_arch_ops" header too ?

I suspect, your compiler supports __atomic intrinsics, so core_ops_gcc_atomic.hpp is implementing the atomic operations. For completeness, core_arch_ops_gcc_ppc.hpp needs to be updated too.

[Lastique]

I have something like this in mind:

#if !defined(_AIX)
#define BOOST_ATOMIC_DETAIL_PPC_ASM_LABEL(label) label ":\n\t"
#define BOOST_ATOMIC_DETAIL_PPC_ASM_JUMP(insn, label, offset) insn " " label "\n\t"
#else
#define BOOST_ATOMIC_DETAIL_PPC_ASM_LABEL(label)
#define BOOST_ATOMIC_DETAIL_PPC_ASM_JUMP(insn, label, offset) insn " " offset "\n\t"
#endif

And then use these macros in both headers.

[Lastique]

Also, I suppose, _AIX indicates AIX OS. Is there a macro specific to your compiler? I mean, if there is a standard gcc that supports labels on AIX, it would be better to enable labels in the code.

[Helflym]

The problem isn't related to the compiler but the assembler being used behind. I'm currently working with gcc-10, which is supporting labels. But it's calling AIX assembler instead of GNU as, and as far as I know it doesn't allow the "1b","1f" syntax. I'm not sure any macro is able to detect that.

[Lastique]

Thanks, merged.