Pass By Value

General JUCE discussion
21

Ignore this... typo .. reinvestigating...

22

Circa 3% improvement after a number of runs.  Interesting!  Fair play to intel :)  I shall get my hat.  And that's calling my super contrived example:

#include "e.h"
int func(PassInStack s)
{
    return s.a + s.b; 
}
int func(PassInRegister s)
{
    return s.c + s.d; 
}

However!  My PassInRegister called function is using the red zone of the stack for temporary storage to separate the struct to do the addition ... (struct is in RDI, result in EAX)!


_Z4func14PassInRegister:               ## @_Z4func14PassInRegister
    pushq    %rbp
    movq    %rsp, %rbp
    movq    %rdi, -8(%rbp)
    movl    -8(%rbp), %eax
    addl    -4(%rbp), %eax
    popq    %rbp
    retq

I'll contrive the example further ...

23

Which makes it a 7% gain for 128bit structures.  3% for your 64bit one...