On 2012-05-23 19:11, Andrew Wiley wrote:
Ultimately, it doesn't really change the number of steps required:
(Foo -> Bar means a compiler that runs on Foo and outputs binaries that
run on Bar)
Standard cross compiler sequence:
1. Compile DC (Foo -> Bar) on Foo using the existing DC (Foo -> Foo)
2. Compile DC (Bar -> Bar) on Foo using the newly built DC (Foo -> Bar)
Now you have Bar -> Bar, which is what you wanted, and we had to build
DC twice. DC also has to support codegen for both Foo and Bar.
What you seem to be wanting is this:
1. Compile DC ((C code) -> Bar) on Foo using the existing DC (Foo ->
{Foo,C})
2. Use the C compiler on Bar to turn (C code) -> Bar into Bar -> Bar
(but this build is slow because it used C as an intermediate form)
3. Use the slow Bar -> Bar to compile a fast Bar -> Bar
Again, we have Bar -> Bar after two builds of DC, but DC had to support
codegen for Foo, Bar, and C.
Targeting C doesn't really seem to make bootstrapping like this any more
efficient.
Then what's the problem.
Unfortunately, I don't really have a satisfying solution to this. At the
moment, we're reinventing the wheel. The best alternative I see if a
library like this were to exist would be to port it instead of
reinventing it. Maybe using it from a VM wouldn't be as hard as I'm
thinking, but it's hard to speculate.
I might be less of a problem when the language isn't changed that much.
On the other hand if you have a compiler library you can build a
tool based on the library that translates D code to Java, C# or
perhaps their byte code equivalents. Then you can automatically
translate the compiler library to whatever language you like and
integrate it with VM-based IDE's.
I agree with Roman that automated translation to a VM language would
probably be a difficult thing to attempt, although I think it could be
doable. I don't think the effort/benefit ration is low enough. It's not
often that someone needs a mechanical translation of a D library to
another language.
Perhaps a tool for automatically creating bindings to the compiler
library. But then I don't know how efficient it would be to move the
necessary data across the VM boundaries.
--
/Jacob Carlborg
