Did some checking of the test I copied the code from, and I forgot that
Rika's original code only exited once a certain time period had elapsed
(e.g. 0.5 seconds). I had changed it to a standard iteration count
since I was concerned about fairness and accuracy, but I only changed
the loop condition and nothing else.
Kit
On 08/10/2023 11:06, Marģers . via fpc-devel wrote:
1. why you leave "time:=..." in benchmark loop? It does add 50% of
execution time per call.
2. Pascal version does not match assembler version. Had to fix it.
//Result := X + Counter + $87654321;
Result:=Result + X + $87654321;
Result:=Result xor y;
3. Assembler functions can be unified to work under win64,win32, linux
64, linux 32
function Checksum_LEA(const Input, X, Y: LongWord): LongWord;
assembler; nostackframe;
asm
@Loop2:
LEA Input, [Input + X + $87654321]
XOR Input, y
DEC y
JNZ @Loop2
MOV EAX, Input
end;
4. My results. Ryzen 2700x
Pascal control case: 0.7 ns/call 0.0710
Using LEA instruction: 0.7 ns/call 0.0700
Using ADD instructions: 0.7 ns/call 0.0710
Even thou results are equal, i was able to add 4 independent ADD
instructions around LEA while results didn't chance, but only 2 around
ADD.
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