Re: [Caml-list] Linear Scan Register Allocator for ocamlopt/ocamlnat

[Gabriel Scherer <gabriel.scherer@gmail.com>]

This work is meant to make a compromise between generated code quality
and compilation speed to have good performances in rapid
prototyping/development scenario.

Do you have more precise measurements on
- the relative costs of the successive transformations during native
compilation (including external linking etc.)? Which proportion of
time is currently used for register allocation?
- the performance cost of this new allocator in the generated code? I
suppose the results may vary between different architectures (eg. x86
is probably more sensitive to good allocation decisions than x86_64).

On Mon, Aug 1, 2011 at 4:53 PM, Benedikt Meurer
<benedikt.meurer@googlemail.com> wrote:
> Hello,
>
> As mentioned earlier we have a student working on an implementation of the Linear Scan Register Allocator [1] for ocamlopt (and thereby ocamlnat). It took some time, but now there's a first working patch which looks promising. This work is done by Marcell Fischbach as part of his diploma thesis. The idea is to use the linear scan algorithm to drive the register allocation in the native top-level ocamlnat at some point, as suggested by Fabrice Le Fessant [2].
>
> Marcell is now working to implement a proof-of-concept of an inline assembler for ocamlnat on i386 based on code from Alain Frisch an Fabrice Le Fessant. The result will also be contributed once ready, and will be used to effectively compare ocamlnat and the byte-code ocaml top-level.
>
> The linear scan implementation reuses as much of the existing ocamlopt functionality as possible, so additional maintenance overhead should be manageable. Comments and suggestions are welcome of course. Please keep Marcell CC'ed with any replies as he's not subscribed to the list.
>
> greets,
> Benedikt
>
>
> [1] http://portal.acm.org/citation.cfm?id=330250
> [2] http://caml.inria.fr/pub/ml-archives/caml-list/2010/11/a1b0ed0934ff51df4ac07c5e9da6e9d6.en.html
>
>
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