int test1(int x) {
	return x;
}

int test2(const int &x) {
	return x;
}

const int &test3(const int &x) {
	return x;
}

int main() {
	int x = 1;
	for(size_t i=0 ; i<0xFFFFFFF; ++i)
   		//testN(x);
}

//// empty loop
real	0m0.721s
user	0m0.713s
sys	0m0.002s

//// test1
real    0m1.325s
user    0m1.320s
sys     0m0.002s

//// test2
real    0m1.242s
user    0m1.239s
sys     0m0.002s

//// test3
real    0m1.075s
user    0m1.072s
sys     0m0.002s

struct A {
	A() :val_(0) {
	}

    int byValue() const {
        return val_;
    }
    
    const int &byReference() const {
        return val_;
    }

    const int *const byPointer() const {
        return &val_;
    }
    
    void setByValue(int val) {
        val_ = val;
    }
    
    void setByReference(const int &val) {
        val_ = val;
    }
    
    void setByPointer(const int *const val) {
        val_ = *val;
    }

    int val_;
};

int main() {
 	int x = 1;
 	A a;

    int val = a.byValue();
    const int &ref = a.byReference();
    const int *const ptr = a.byPointer();

    a.setByValue(x);
    a.setByReference(x);
    a.setByPointer(&x);
}

/// main
0x0000000100000a28  <+0000>  push   %rbp
0x0000000100000a29  <+0001>  mov    %rsp,%rbp
0x0000000100000a2c  <+0004>  sub    $0x30,%rsp
0x0000000100000a30  <+0008>  movl   $0x1fffffff,-0x4(%rbp)
0x0000000100000a37  <+0015>  movl   $0x1,-0x8(%rbp)
0x0000000100000a3e  <+0022>  lea    -0x10(%rbp),%rdi
0x0000000100000a42  <+0026>  callq  0x100000bc2 <_ZNK1A7byValueEv>
0x0000000100000a47  <+0031>  mov    %eax,-0x14(%rbp)
0x0000000100000a4a  <+0034>  lea    -0x10(%rbp),%rdi
0x0000000100000a4e  <+0038>  callq  0x100000bd2 <_ZNK1A11byReferenceEv>
0x0000000100000a53  <+0043>  mov    %rax,-0x20(%rbp)
0x0000000100000a57  <+0047>  lea    -0x10(%rbp),%rdi
0x0000000100000a5b  <+0051>  callq  0x100000be0 <_ZNK1A9byPointerEv>
0x0000000100000a60  <+0056>  mov    %rax,-0x28(%rbp)
0x0000000100000a64  <+0060>  mov    -0x8(%rbp),%esi
0x0000000100000a67  <+0063>  lea    -0x10(%rbp),%rdi
0x0000000100000a6b  <+0067>  callq  0x100000bee <_ZN1A10setByValueEi>
0x0000000100000a70  <+0072>  lea    -0x8(%rbp),%rsi
0x0000000100000a74  <+0076>  lea    -0x10(%rbp),%rdi
0x0000000100000a78  <+0080>  callq  0x100000c04 <_ZN1A14setByReferenceERKi>
0x0000000100000a7d  <+0085>  lea    -0x8(%rbp),%rsi
0x0000000100000a81  <+0089>  lea    -0x10(%rbp),%rdi
0x0000000100000a85  <+0093>  callq  0x100000c1e <_ZN1A12setByPointerEPi>
0x0000000100000a8a  <+0098>  mov    $0x0,%eax
0x0000000100000a8f  <+0103>  leaveq 
0x0000000100000a90  <+0104>  retq


//byValue
0x0000000100000bc2  <+0000>  push   %rbp
0x0000000100000bc3  <+0001>  mov    %rsp,%rbp
0x0000000100000bc6  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000bca  <+0008>  mov    -0x8(%rbp),%rax
0x0000000100000bce  <+0012>  mov    (%rax),%eax
0x0000000100000bd0  <+0014>  leaveq 
0x0000000100000bd1  <+0015>  retq

//byReference
0x0000000100000bd2  <+0000>  push   %rbp
0x0000000100000bd3  <+0001>  mov    %rsp,%rbp
0x0000000100000bd6  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000bda  <+0008>  mov    -0x8(%rbp),%rax
0x0000000100000bde  <+0012>  leaveq 
0x0000000100000bdf  <+0013>  retq

//byPointer
0x0000000100000be0  <+0000>  push   %rbp
0x0000000100000be1  <+0001>  mov    %rsp,%rbp
0x0000000100000be4  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000be8  <+0008>  mov    -0x8(%rbp),%rax
0x0000000100000bec  <+0012>  leaveq 
0x0000000100000bed  <+0013>  retq

//setByValue
0x0000000100000bee  <+0000>  push   %rbp
0x0000000100000bef  <+0001>  mov    %rsp,%rbp
0x0000000100000bf2  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000bf6  <+0008>  mov    %esi,-0xc(%rbp)
0x0000000100000bf9  <+0011>  mov    -0x8(%rbp),%rdx
0x0000000100000bfd  <+0015>  mov    -0xc(%rbp),%eax
0x0000000100000c00  <+0018>  mov    %eax,(%rdx)
0x0000000100000c02  <+0020>  leaveq 
0x0000000100000c03  <+0021>  retq

//setByReference
0x0000000100000c04  <+0000>  push   %rbp
0x0000000100000c05  <+0001>  mov    %rsp,%rbp
0x0000000100000c08  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000c0c  <+0008>  mov    %rsi,-0x10(%rbp)
0x0000000100000c10  <+0012>  mov    -0x10(%rbp),%rax
0x0000000100000c14  <+0016>  mov    (%rax),%edx
0x0000000100000c16  <+0018>  mov    -0x8(%rbp),%rax
0x0000000100000c1a  <+0022>  mov    %edx,(%rax)
0x0000000100000c1c  <+0024>  leaveq 
0x0000000100000c1d  <+0025>  retq

//setByPointer
0x0000000100000c1e  <+0000>  push   %rbp
0x0000000100000c1f  <+0001>  mov    %rsp,%rbp
0x0000000100000c22  <+0004>  mov    %rdi,-0x8(%rbp)
0x0000000100000c26  <+0008>  mov    %rsi,-0x10(%rbp)
0x0000000100000c2a  <+0012>  mov    -0x10(%rbp),%rax
0x0000000100000c2e  <+0016>  mov    (%rax),%edx
0x0000000100000c30  <+0018>  mov    -0x8(%rbp),%rax
0x0000000100000c34  <+0022>  mov    %edx,(%rax)
0x0000000100000c36  <+0024>  leaveq 
0x0000000100000c37  <+0025>  retq

//// by reference
int main() {
    A a;
    
    a.setByReference(3);
    const int &ref = a.byReference();

    std::cout<<ref<<std::endl;
}

//// by value
int main() {
    A a;
    
    a.setByValue(3);
    int val = a.byValue();
    
    std::cout<<val<<std::endl;
}

0x0000000100000d91  <+0000>  push   %rbp
0x0000000100000d92  <+0001>  mov    %rsp,%rbp
0x0000000100000d95  <+0004>  mov    $0x3,%esi
0x0000000100000d9a  <+0009>  mov    0x297(%rip),%rdi        # 0x100001038
0x0000000100000da1  <+0016>  callq  0x100000dfa <dyld_stub__ZNSolsEi>
0x0000000100000da6  <+0021>  mov    %rax,%rdi
0x0000000100000da9  <+0000>  callq  0x100000e0c <dyld_stub__ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_>
0x0000000100000dae  <+0029>  xor    %eax,%eax
0x0000000100000db0  <+0031>  leaveq 
0x0000000100000db1  <+0032>  retq