Optimisation possibilities: current, future and enhancements

[Cecil Ward via Digitalmars-d]

On Thursday, 25 August 2016 at 17:22:27 UTC, kinke wrote:
> I found it hard to believe LDC generates such crappy code when 
> optimizing. These are my results using LDC master on Win64 
> (`ldc2 -O -release -output-s`):
>
> struct Foo
> {
>     immutable _u = 8;
>     int foo() const
>     {
>         return 8 * _u;
>     }
> }
> int use(ref const(Foo) foo)
> {
>     return foo.foo() + foo.foo();
> }
>
> int main()
> {
>     Foo f;
>     return use(f);
> }
>
>
> _D7current3Foo3fooMxFZi:
> 	movl	(%rcx), %eax
> 	shll	$3, %eax
> 	retq
>
> _D7current3useFKxS7current3FooZi:
> 	movl	(%rcx), %eax
> 	shll	$4, %eax
> 	retq
>
> _Dmain:
> 	movl	$128, %eax
> 	retq
>
> Sure, Foo.foo() and use() could return a constant, but 
> otherwise it can't get much better than this.

I think that here the optimisation is only because LDC can “see” 
the text of the method. When expansion is not possible, that 
would be the real test.