DMD backend quality (Was: Re: DIP 1031--Deprecate Brace-Style Struct Initializers--Community Review Round 1 Discussion)

[Walter Bright]

On 2/18/2020 1:52 PM, H. S. Teoh wrote:
> DMD's inliner, in comparison, balks at the sight of
> things as trivial as writing:
> 
> 	auto myFunc(...) {
> 		if (cond) return result1;
> 		return result2;
> 	}
> 
> vs.
> 
> 	auto myFunc(...) {
> 		if (cond) return result1;
> 		else return result2;
> 	}

With:

   int fooa(int a, int b, int c) {
     if (a)
	return b;
     return c;
   }

   int foob(int a, int b, int c) {
     if (a)
	return b;
     else
	return c;
   }

   int test(int a, int b, int c) {
     return fooa(a, b, c) + foob(a, b, c);
   }

the generated code for test() compiled with -inline -O is:

                 push    EAX
                 cmp     dword ptr 0Ch[ESP],0
                 je      LE
                 mov     EAX,8[ESP]
                 jmp short       L11
   LE:           mov     EAX,[ESP]
   L11:          add     EAX,EAX
                 pop     ECX
                 ret     8

so it is inlining both forms. If you do have trivial functions that aren't being 
inlined, please let me know. Thanks!