The current phobos hello world
import std.stdio;
void main() { "Hello World".writeln; }
generates a list of 36 functions which are generated and emitted but not called, and therefore presumably only used at compile time

Those are:

std.typecons.__lambda252|/usr/include/dmd/phobos/std/typecons.d(7277)
std.stdio.File.ByChunkImpl.~this|/usr/include/dmd/phobos/std/stdio.d(2615)
std.stdio.File.ByChunkImpl.__fieldPostblit|/usr/include/dmd/phobos/std/stdio.d(2615)
std.typecons.Ternary.make|/usr/include/dmd/phobos/std/typecons.d(9034)
std.stdio.File.LockingTextWriter.~this|/usr/include/dmd/phobos/std/stdio.d(2861)
std.traits.DynamicArrayTypeOf(T)|/usr/include/dmd/phobos/std/traits.d(5791)
std.range.primitives.empty!(const(char)[]).empty|/usr/include/dmd/phobos/std/range/primitives.d(2184)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(173)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(174)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(175)
object.__equals!(immutable(char), immutable(char)).__equals.__lambda3|/usr/include/dmd/druntime/import/object.d(398)
object.__equals!(immutable(char), immutable(char)).__equals.at!(immutable(char)).at|/usr/include/dmd/druntime/import/object.d(358)
object.__equals!(immutable(char), immutable(char)).__equals|/usr/include/dmd/druntime/import/object.d(352)
std.functional.safeOp!"<".safeOp!(ulong, immutable(ubyte)).safeOp|/usr/include/dmd/phobos/std/functional.d(446)
std.algorithm.comparison.min!(ulong, immutable(ubyte)).min|/usr/include/dmd/phobos/std/algorithm/comparison.d(1641)
std.range.primitives.popFront!char.popFront|/usr/include/dmd/phobos/std/range/primitives.d(2254)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(176)
std.utf.decodeImpl!(true, cast(Flag)false, const(char)[]).decodeImpl.exception!(const(char)[]).exception|/usr/include/dmd/phobos/std/utf.d(1491)
std.utf.decodeImpl!(true, cast(Flag)false, const(char)[]).decodeImpl.invalidUTF|/usr/include/dmd/phobos/std/utf.d(1505)
std.utf.decodeImpl!(true, cast(Flag)false, const(char)[]).decodeImpl.outOfBounds|/usr/include/dmd/phobos/std/utf.d(1522)
std.utf.decodeImpl!(true, cast(Flag)false, const(char)[]).decodeImpl|/usr/include/dmd/phobos/std/utf.d(1447)
std.utf.decode!(cast(Flag)false, const(char)[]).decode|/usr/include/dmd/phobos/std/utf.d(1127)
std.range.primitives.front!char.front|/usr/include/dmd/phobos/std/range/primitives.d(2454)
std.range.primitives.empty!string.empty|/usr/include/dmd/phobos/std/range/primitives.d(2184)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(173)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(174)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(175)
std.range.primitives.isInputRange(R)|/usr/include/dmd/phobos/std/range/primitives.d(176)
std.range.primitives.isInfinite(R)|/usr/include/dmd/phobos/std/range/primitives.d(1621)
std.exception.enforce!(ErrnoException).enforce!int.enforce.__lambda1|/usr/include/dmd/phobos/std/exception.d(434)
object.idup!(const(char)).idup.__lambda2|/usr/include/dmd/druntime/import/object.d(4578)
object._getPostblit!(immutable(char))._getPostblit.__dgliteral1|/usr/include/dmd/druntime/import/object.d(4652)
std.stdio.File.LockingTextWriter.put!string.put.__dgliteral2|/usr/include/dmd/phobos/std/stdio.d(2899)
std.range.primitives.front!char.front|/usr/include/dmd/phobos/std/range/primitives.d(2454)
object.__equals!(immutable(char), immutable(char)).__equals|/usr/include/dmd/druntime/import/object.d(352)

So you can see that there is something to be won even in the most trivial examples if we have facilities to disable codegen for functions which are only used at compiletime.

On Wednesday, 8 April 2020 at 13:57:47 UTC, Stefan Koch wrote:
> The current phobos hello world
> import std.stdio;
> void main() { "Hello World".writeln; }
> generates a list of 36 functions which are generated and emitted but not called, and therefore presumably only used at compile time
>
> Those are:
>
> [...]
>
> So you can see that there is something to be won even in the most trivial examples if we have facilities to disable codegen for functions which are only used at compiletime.

Are you sure that this is not also caused by bad speculative template instantiation ?
In case I'd use the wrong wording, I mean "some function templates that are wrongly determined to be emitted ".

On Wednesday, 8 April 2020 at 14:08:23 UTC, Basile B. wrote:
> On Wednesday, 8 April 2020 at 13:57:47 UTC, Stefan Koch wrote:
>> The current phobos hello world
>> import std.stdio;
>> void main() { "Hello World".writeln; }
>> generates a list of 36 functions which are generated and emitted but not called, and therefore presumably only used at compile time
>>
>> Those are:
>>
>> [...]
>>
>> So you can see that there is something to be won even in the most trivial examples if we have facilities to disable codegen for functions which are only used at compiletime.
>
> Are you sure that this is not also caused by bad speculative template instantiation ?
> In case I'd use the wrong wording, I mean "some function templates that are wrongly determined to be emitted ".

That might very well be the cause.
Most of those would however benefit from being annotated ctfe-only.

On Wednesday, 8 April 2020 at 14:10:48 UTC, Stefan Koch wrote:
> On Wednesday, 8 April 2020 at 14:08:23 UTC, Basile B. wrote:
>>
>>
>> Are you sure that this is not also caused by bad speculative template instantiation ?
>> In case I'd use the wrong wording, I mean "some function templates that are wrongly determined to be emitted ".
>
> That might very well be the cause.
> Most of those would however benefit from being annotated ctfe-only.

Having the meta information about a function template,
that it is not supposed to be emitted of course will also help,
when debugging the algorithm that determines template emission.

On Wednesday, 8 April 2020 at 13:57:47 UTC, Stefan Koch wrote:
> The current phobos hello world
> import std.stdio;
> void main() { "Hello World".writeln; }
> generates a list of 36 functions which are generated and emitted but not called, and therefore presumably only used at compile time
>
> [...]

This is uncalled for.

On Wed, Apr 08, 2020 at 03:50:41PM +0000, Jonathan Marler via Digitalmars-d wrote:
> On Wednesday, 8 April 2020 at 13:57:47 UTC, Stefan Koch wrote:
> > The current phobos hello world
> > import std.stdio;
> > void main() { "Hello World".writeln; }
> > generates a list of 36 functions which are generated and emitted but
> > not called, and therefore presumably only used at compile time
> > 
> > [...]
> 
> This is uncalled for.

LOL!


T

-- 
Leather is waterproof.  Ever see a cow with an umbrella?

On Wednesday, 8 April 2020 at 13:57:47 UTC, Stefan Koch wrote:
> The current phobos hello world
> import std.stdio;
> void main() { "Hello World".writeln; }
> generates a list of 36 functions which are generated and emitted but not called, and therefore presumably only used at compile time
>
> Those are:
>
> [...]

Now that I read those 36 calls carefully it really looks like there's among them some used when writeln!string fails and throws, e.g when decoding the argument.