Overloading Lazy Vs. Non-Lazy

[Don]

Steven Schveighoffer wrote:
> On Thu, 12 Aug 2010 02:00:00 -0400, Brad Roberts <braddr at puremagic.com> 
> wrote:
> 
>> On 8/11/2010 6:19 AM, dsimcha wrote:
>>> An issue that's come up here several times before is that enforce()
>>> effectively disables inlining of the function it's used in.  From 
>>> reading some
>>> disassemblies, the reason seems to be because of all the ASM code that's
>>> required for lazy parameters.  I wonder if either of the following is 
>>> feasible:
>>>
>>> 1.  When a function takes a lazy parameter, the compiler automatically
>>> generates two versions under the hood:  One that actually takes a 
>>> non-lazy
>>> parameter and is used when the value is known at compile time and 
>>> another that
>>> works like current lazy functions.  The only problem here is that 
>>> this might
>>> create issues when using function pointers/delegates.
>>>
>>> 2.  Allow overloading of lazy and non-lazy functions, with the rule 
>>> that the
>>> lazy version gets called whenever the value must be computed at 
>>> runtime and
>>> the non-lazy version gets called if the value is statically known and 
>>> thus
>>> there's no evaluation to speak of.
>>
>> It's the throw that blocks inlining right now.  Lazy might also 
>> disable inlining
>> too, I haven't looked for that case.  Either way, that's purely a 
>> quality of
>> implementation issue.  I don't think it'd be a good idea to bend the 
>> library all
>> that much to work around that kind of limitation.  It's something that 
>> will get
>> better as time permits.
> 
> Well, there's something to be said about preventing the bloated 
> generation of code that accompanies lazy.

Inlining a lazy function that only returns a compile-time constant could 
inline very nicely. The delegate would disappear completely.

> But throwing preventing inlining is a bad one, that should be fixed.
> 
> -Steve