rvalues -> ref (yup... again!)

[Rubn]

On Wednesday, 28 March 2018 at 00:56:29 UTC, kinke wrote:
> On Tuesday, 27 March 2018 at 23:59:09 UTC, Rubn wrote:
>> Just adding a few writeln it isn't able to remove the function 
>> entirely anymore and can't optimize it out.
>
> Well writeln() here involves number -> string formatting, GC, 
> I/O, template bloat... There are indeed superfluous memcpy's in 
> your foo() there (although the forward and bar calls are still 
> inlined), which after a quick glance seem to be LLVM optimizer 
> shortcomings, the IR emitted by LDC looks fine.
> For an abitrary external function, it's all fine as it should 
> be, boiling down to a single memcpy in foo() and a direct 
> memset in main(): https://run.dlang.io/is/O1aeLK

Well somethings wrong if writeln causes optimization to not 
occur, if that is the case then it'd be best to just use printf() 
instead. Anyways using small examples to show optimization is 
usually not what's going to happen in actual code. Functions are 
rarely that simple, and if adding a single writeln() to a call is 
enough to eliminate that optimization, I can only imagine what 
other little things do as well.