make case tables immutable

[MartinNowak]

• Avoids redundant object copies and semantic
  analysis for every usage.
• Multilib archives or gc-sections will take care
  of the binary size issue.

[DmitryOlshansky]

LGTM, I'll adjust the generator accordingly.

[MartinNowak]

LGTM, I'll adjust the generator accordingly.

I see, where is the generator?

[MartinNowak]

I found a few more ways to optimize compile time and object sizes.

[MartinNowak]

If making a .di file turns out to be too hard we might be able to only import std.internal.unicode_tables in the remaining templates, so that it's rarely ever imported.

[DmitryOlshansky]

I see, where is the generator?

ATM here:
https://github.com/blackwhale/gsoc-bench-2012/blob/master/gen_uni.d

I plan to one day move it to DLang tools repo.

[DmitryOlshansky]

Another thought is probably split it up (e.g. 3 pieces - tries, sets and case entries) and use local imports in specific functions.

[DmitryOlshansky]

Last thing that worries me is inlining or more preciesly the lack of it, see also:
dlang/dmd#2561

[WalterBright]

There's nothing hard about writing a .di file. It's just a list of declarations.

[DmitryOlshansky]

There's nothing hard about writing a .di file. It's just a list of declarations.

But it doesn't help matters as it kills CTFE-ablity of std.uni (and consequently all of string/formatting code in Phobos).

[MartinNowak]

The function overload trick already heavily reduces compile time and template bloat for common use cases.
I think we can live with the fact that calling sicmp with non-strings requires some template instantiations.
The only performance penalty left is parsing std.internal.unicode_tables which can be mitigated by localizing the import.
Can we merge this? I'll make a pull for the generator.

[WalterBright]

Merging this did NOT decrease "hello world" size, it INCREASED it by 100Kb !

(On Windows 32)

[MartinNowak]

Merging this did NOT decrease "hello world" size, it INCREASED it by 100Kb !

(On Windows 32)

Ouch, I made this pull request to address the compile time issue and found some ways to deduplicate tables in different template instantiations. The hello world size was not what I optimized for.
The size of hello world increased because of something that I didn't knew, multilib only works for functions not for data.
Part of this pull request was to write immutable tables into phobos instead of generating them in every template instance (MartinNowak@45c873f).
Now the problem is that phobos contains a monolithic unicode_tables.o (343kB nm -S output). We could put the tables into functions to workaround the issue, the real solution though is to extend multilib to data or to fix the outstanding gc-section issues.

[WalterBright]

Sure, but extending multilib to data is not going to happen for 2.064. We need a fix for 2.064.

[MartinNowak]

Sure, but extending multilib to data is not going to happen for 2.064. We need a fix for 2.064.

Wrapping the data in @property functions will fix the size issue, though it might cause inline problems.
I'll have to wait for @blackwhale to fix or explain how the gen_uni works because I can't get it to run and I don't want to spend hours on editing the generated file by hand.

[MartinNowak]

Multilib archives or gc-sections will take care
of the binary size issue.

Here is the pull that will make use of multilib #1647, trims hello world by ~300kB.