On Sunday, 11 March 2012 at 06:49:27 UTC, H. S. Teoh wrote:
On Sun, Mar 11, 2012 at 01:29:01AM -0500, Nick Sabalausky wrote:
Suppose you have a delegate literal and immediately call it:
auto a = x + (){ doStuff(); return y; }() + z;
Does DMD ever (or always?) optimize away a delegate if it's
executed
immediately and never stored into a variable? If not, can it,
and
would it be a simple change? Is something like this already on
the
table?
[...]
I've always wondered about whether delegates passed to opApply
ever get
inlined.
Don't wonder. Find out!
import std.stdio;
void doStuff() { writeln("Howdy!"); }
void main() {
int x = 1, y = 2, z = 3;
auto a = x + (){ doStuff(); return y; }() + z;
writeln(a);
}
$ dmd test.d -O -release -inline
__Dmain:
000000010000106c pushq %rbp
000000010000106d movq %rsp,%rbp
0000000100001070 pushq %rax
0000000100001071 pushq %rbx
0000000100001072 movq $0x000000000000000c,%rdi
000000010000107c callq 0x1000237f0 ; symbol stub for:
__d_allocmemory
0000000100001081 movq %rax,%rbx
0000000100001084 movq $0x00000000,(%rbx)
000000010000108b movl $0x00000002,0x08(%rbx)
0000000100001092 movq %rbx,%rdi
0000000100001095 call *0x0002318c(%rip)
000000010000109c leal 0x04(%rax),%edx
000000010000109f movl $0x0000000a,%esi
00000001000010a4 leaq 0x00033eed(%rip),%rdi
00000001000010ab callq 0x10002319c ; symbol stub for:
_D3std5stdio4File14__T5writeTiTaZ5writeMFiaZv
00000001000010b0 xorl %eax,%eax
00000001000010b2 popq %rbx
00000001000010b3 movq %rbp,%rsp
00000001000010b6 popq %rbp
00000001000010b7 ret
In short. No! It doesn't currently inline in this case.
Even if the lambda just returns a constant, it doesn't get
inlined.
