On Monday, 3 August 2015 at 16:41:42 UTC, Steven Schveighoffer
wrote:
On 8/3/15 12:31 PM, Dmitry Olshansky wrote:
On 03-Aug-2015 19:27, aki wrote:
When I was trying to port some Java program to D,
I noticed Java is faster than D.
I made a simple bench mark test as follows.
Then, I was shocked with the result.
test results on Win8 64bit (smaller is better)
Java(1.8.0,64bit,server): 0.677
C++(MS vs2013): 2.141
C#(MS vs2013): 2.220
D(DMD 2.067.1): 2.448
D(GDC 4.9.2/2.066): 2.481
Java(1.8.0,32bit,client): 3.060
Does anyone know the magic of Java?
Thanks, Aki.
Devirtualization? HotSpot is fairly aggressive in that regard.
Yeah, I think that's it. virtual calls cannot be inlined by the
D compiler, but could be inlined by hotspot. You can fix this
by making the derived class final, or marking the method final,
and always using a reference to the derived type. If you need
virtualization still, you will have to deal with lower
performance.
-Steve
Yup. I get very similar numbers to aki for his version, but
changing two lines:
final class SubFoo : Foo {
int test(F)(F obj, int repeat) {
or less generally:
int test(SubFoo obj, int repeat) {
gets me down to 0.182s with ldc on OS X
