On Wed, 14 Mar 2012 13:45:13 -0700, Alvaro <[email protected]>
wrote:
El 19/12/2011 9:11, Adam Wilson escribió:
1. Function Implementations are removed
What about function inlining? would it work from a different module?
I think the implementation of small functions should be kept so that
client code can inline them.
The current DMD does this apparently, it keeps small functions in .di
files.
The problem is that in DI generation, at least as near as I can tell, D
has now idea how big a function is during DI generation. In my experience
it was keeping all functions not just small ones. And frankly DI
generation is targeted at library builders who are well aware of the
inlining trade-offs. And then comes the question of how do you define
"small functions" to an adequately technical level. Because theoretically
you can inline ANYTHING. Yes, there are rules the prevent inlining, but
you'll also note that the state of these rules is not guaranteed to be
known at generation time.
DI generation currently works as such. After the code has been parsed into
an AST, the compiler runs a special set of virtual functions called
toCBuffer (and it's variants) that is used to print out the AST in source
form again. NO semantic analysis of any kind has been performed on the AST
yet. And you wouldn't want to generate DI's after semantic analysis as the
analysis fundamentally alters the AST such that you would not get the same
code back out and some things would be missing from the DI files that you
intended to be there. The AST at DI generation is an incredibly naive
representation of the SOURCE not the SEMANTICS; which is what you would
need to determine the eligibility of inlining.
The answer that Walter has always given for objections about how DI files
are built is that if you want anything customized about the output, you
have to do it yourself. DI generation will probably NEVER be as perfect as
everyone wants. But I think this solution represents a best effort to get
DI files to a point where the community agrees that they would be most
useful in achieving their intended purpose, which is as interface files
for compiled libraries. It's not perfect, but it gets you A LOT further
than the current one, if you need customization beyond that, well, D lets
you do that too. :-)
--
Adam Wilson
Project Coordinator
The Horizon Project
http://www.thehorizonproject.org/
