Re: [Caml-list] whither portability?

[whitequark <whitequark@whitequark.org>]

On 2015-09-27 03:55, Raoul Duke wrote:
>> Both ocamlc and ocamlopt work for iOS and Android; there is not really
>> a good reason to use the bytecode compiler for deployment to mobile.
>> 
>> There is no such thing as "LLVM bytecode" and LLVM bitcode (sic)
>> is merely an intermediate format for native executable code. Shipping
>> LLVM bitcode offers no conceptual improvement over shipping
>> machine code and in any case, there is neither an LLVM backend
>> for ocamlopt nor much need for such a backend.
> 
> Yes, "bitcode" is the right term. It is now the format Apple wants. So
> I dunno why people would actively discount it here.

Right now, LLVM IR (of which the bitcode is a serialization) is not
flexible enough to express the invariants and metadata required
for the OCaml GC to function[1]. Even if someone released the necessary,
highly nontrivial changes to both LLVM and OCaml today, it would take
many months for them to be reviewed, merged & propagated into Apple's
LLVM fork--all for a small improvement in a select few numeric workloads
that can benefit from using the instruction selector tailored for
the particular device, and a substantial reduction in being able to
debug your code[2].

[1]: 
https://github.com/whitequark/ocaml-llvm-ng/issues/1#issuecomment-141844579
[2]: 
https://medium.com/@FredericJacobs/why-i-m-not-enabling-bitcode-f35cd8fbfcc5

-- 
whitequark