On Sunday, 22 December 2013 at 08:11:05 UTC, Russel Winder wrote:
Historically, and anecdotally, I found that as soon as the
assembly
language was a function, it was better as a separate entity,
Well, you can usually get what you want by first writing the code
in C, then generate asm and optimize that by hand. So, being able
to generate useful asm listings is more important than inlining,
I think. In that respect I agree. I would much rather have the
ability to generate tight and readable/auto-commented ASM than
having inlining.
that inline
assembler only worked for accessing a processor instruction
that the
code generator could not generate. So I think you are making
this same
point, cf. SIMD instructions at the bleeding edge.
Well, yes, but if you are doing projects where you know the
hardware and the hardware is specialized and limited (e.g. tiny
amounts of RAM/ROM, no division/multiply, System on a Chip etc)
it becomes a little bit more attractive to be able to do asm here
and there: get the most out of flag-registers (like carry,
overflow etc), run without an OS and write tight IRQ handlers.
Like art-installations, small robots, embedded things? Granted,
this is not something D is suitable for atm, but I hope it will
move in that direction, eventually. I think it could become a hit.
Regarding bleeding edge: AFAIK, inlined asm is necessary if you
want to benefit effectively from transactional memory in Haswell
processors today, although it would be much much more convenient
with language support. It is hard to get right, because there are
cache-line restrictions (objects have a minimum/maximum size, so
you have to group attributes that are to be protected into the
same region). I think inline asm might be useful in a heavily
optimized single-purpose server for that reason. But to
conveniently benefit from that the compiler have to generate ASM
that the CPU-vendor's assembler can parse and without
restrictions on instructions unknown to the compiler (so you
don't have to resort to injecting opcodes rather than mnemonics).
If inline asm implies a built in assembler then I am not at all
sure if it is all that useful.
