Paulo Costa wrote:
At 18:46 02/01/2008, willem wrote:
Vincent has made an improved Mandelbrot benchmark.
i did run the original mandelbrot benchmark with N =5000. It took 2:
20 minutes.
The improved version took 2:00 minutes.
If you see the gcc version you'll see that it relies on SSE2
instructions to perform two double computations with one instruction:
http://shootout.alioth.debian.org/gp4/benchmark.php?test=mandelbrot&lang=gcc&id=3
"
Uses SSE packed doubles to run the inner loop computations in parallel.
I don't have a machine with SSE to test with, but the assembly looks
pretty nice. With gcc-3.4.2 there's no difference in the assembly
between -msse2 and -msse3, YMMV. It uses gcc's vector extentions
( http://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Vector-Extensions.html ),
so it will run (slowly) on hardware without SSE.
"
That is why it is twice as fast. The "-funroll-loops" may help a bit
also, because it is very aggressive and can eradicate some loop
variables...
I think that the only "easy" way for fpc to be competitive in cases
like these is to have explicit types for MMX and SSEn data and the
"functions" to operate with them, like gcc does...
And, no I'm not the one who can send those patches :(
Paulo Costa
Yes I agree with you I have here an example:
Program sse;
{$mode objfpc}{$H+}
{FPUTYPE SSE2}{$i-}
type ZVector =record
i: double;
r : double;
end ;
type Tvector =record
i :double;
r : double;
end;
var vecZ : ZVector;
vecT : Tvector;
begin
with vecZ do
begin
i := 0.5;
r := 1.5;
end;
asm {mulltiply parameters}
movups xmm1, vecZ
mulps xmm1, xmm1
movups vecZ, xmm1
end;
with vecZ do
begin
writeln (i,r);
end;
with vecT do
begin
i := 20.5;
r := 300.5;
end;
asm {multiply parameters}
movups xmm1, vecT
mulps xmm1, xmm1
movups vecT, xmm1
end;
with vecT do
begin
writeln (i,r);
end;
end.
My problem is that I get the errormessage : Assembler not supported.
In mandelbrot.pas the Calulatatepoint is used. If you remove this
function then you can also gain speed.
so
for y := 0 to n do
begin
------
for x := 0 to n-1 do
begin
------
for i := 1 to 50 do
begin
---------
etc
regards Wim
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