int opEquals(Object), and other legacy ints

[xs0]

>> It's a byte internally, and is constrained to be one of the values 0 
>> or 1.
> 
> Duh, it's a byte of course, I should have checked that.
> 
> But the question remains, is it then less efficient to return a byte 
> than a int? Why? And if so isn't there a way for the compiler to somehow 
> optimize it?
> I find it a bit hard to believe that nowadays there isn't sufficient 
> compiler and/or CPU technology to somehow make a bool(byte) return value 
> as efficient as a int one. :/

Well, I'm just guessing, but I think something like

 > int opEquals(Foo foo)
 > {
 >     return this.bar == foo.bar;
 > }

is compiled to something like

 > return this.bar-foo.bar; // 1 instruction

but if the return type is bool, it becomes

 > return this.bar-foo.bar?1:0; // 3 instructions

It's the 1/0 constraint on bools that causes the slowness, not the size 
(stack is usually size_t-aligned anyway)


xs0