On Tuesday, 23 October 2012 at 10:36:11 UTC, Daniel Kozák wrote:
Hi,
First of all, I think there is no difference in speed between
LargeStruct foo, too, temp;
temp = foo - too;
bar.func(temp);
and with func without ref.
That doesn't seem to be the case, as at least DMD always copies
to the stack. Even if I change the function to have the struct
as a unused local variable it still copies.
void example(LargeStruct t, Bar bar)
{
bar.func(t);
}
with ref:
Dump of assembler code for function
_D7example4testFS7example11LargeStructC7example3BarZv:
0x0000000000425ee0 <+0>: push %rbp
0x0000000000425ee1 <+1>: mov %rsp,%rbp
0x0000000000425ee4 <+4>: sub $0x10,%rsp
0x0000000000425ee8 <+8>: lea 0x10(%rbp),%rsi
0x0000000000425eec <+12>: mov (%rdi),%rax
0x0000000000425eef <+15>: rex.W callq *0x30(%rax)
0x0000000000425ef3 <+19>: mov %rbp,%rsp
0x0000000000425ef6 <+22>: pop %rbp
0x0000000000425ef7 <+23>: retq
without ref:
Dump of assembler code for function
_D7example4testFS7example11LargeStructC7example3BarZv:
0x0000000000425ee0 <+0>: push %rbp
0x0000000000425ee1 <+1>: mov %rsp,%rbp
0x0000000000425ee4 <+4>: sub $0x10,%rsp
0x0000000000425ee8 <+8>: lea 0x208(%rbp),%rsi
0x0000000000425eef <+15>: mov $0x40,%ecx
0x0000000000425ef4 <+20>: pushq (%rsi)
0x0000000000425ef6 <+22>: sub $0x8,%rsi
0x0000000000425efa <+26>: loop 0x425ef4
<_D7example4testFS7example11LargeStructC7example3BarZv+20>
0x0000000000425efc <+28>: mov (%rdi),%rax
0x0000000000425eff <+31>: rex.W callq *0x30(%rax)
0x0000000000425f03 <+35>: add $0x200,%rsp
0x0000000000425f0a <+42>: mov %rbp,%rsp
0x0000000000425f0d <+45>: pop %rbp
0x0000000000425f0e <+46>: retq
How looks your opBinary(Right) method?
For eg. this works for me:
struct LargeStruct {
int x;
auto ref opBinary(string op)(LargeStruct rhs) if (op == "-")
{
this.x = this.x - rhs.x;
return this;
}
}
class Bar {
void func(ref LargeStruct st) {}
}
void main(string[] args)
{
Bar bar = new Bar();
LargeStruct foo, too;
bar.func(foo - too);
}
However this will modify foo struct.
Since this is D1 code being ported I'm currently using
opSub. I tried changing your code to opSub and I got the
same error as with mine. Your example should probably be
an error. I'm not saying I was right in doing what I did.
The point of the post was to improve D.
Cheers, Jakob.
