change hash function gives up to 22% speedup

tigrazone commented

2017-10-30 18:59:46 +00:00

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No description provided.

edwinyzh commented

2017-10-31 06:17:14 +00:00

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Wow! Is the 22% speedup affects the entire library when executing JS code?

tigrazone commented

2017-10-31 06:35:27 +00:00

(Migrated from github.com)

not always. 3%-10% speedup when executing JS code.
Maybe you rewrite my hash function in assembler?
bottlenecks is copy functions, .Name = .Name + and balansed tree not too fast.
I also change BESENANSIPos to Pos, BESENANSIPosChar to Pos, BESENANSIUpperCase to UpperCase and BESENANSITrim to Trim. It give me -500 bytes in exe ;-)
Look at my last commit.

not always. 3%-10% speedup when executing JS code. Maybe you rewrite my hash function in assembler? bottlenecks is copy functions, .Name = .Name + and balansed tree not too fast. I also change BESENANSIPos to Pos, BESENANSIPosChar to Pos, BESENANSIUpperCase to UpperCase and BESENANSITrim to Trim. It give me -500 bytes in exe ;-) Look at my last commit.

tigrazone commented

2017-10-31 12:28:25 +00:00

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.Name = .Name +can be changed to add widechars to array and then fast copy to .Name at finish of cycle

data-man commented

2017-10-31 12:47:11 +00:00

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@tigrazone

Maybe you rewrite my hash function in assembler?

Why just assembler? :)
Try this: (taken from awesome blog (in russian))

function ShaPerfectHashStr(const s: RawByteString): integer;
var
  i: integer;
begin;
  Result:=0;
  for i:=0 to Length(s)-1 do Result:=(Result + ord(s[i+1]) + 1507220783) * 1041204193;
end;

Well, and assembler :)
CRC32 parallel calculation
CRC64 parallel calculation

@tigrazone > Maybe you rewrite my hash function in assembler? Why just assembler? :) Try this: (taken from awesome [blog](http://guildalfa.ru/alsha/) (in russian)) ```pascal function ShaPerfectHashStr(const s: RawByteString): integer; var i: integer; begin; Result:=0; for i:=0 to Length(s)-1 do Result:=(Result + ord(s[i+1]) + 1507220783) * 1041204193; end; ``` Well, and assembler :) [CRC32 parallel calculation](http://guildalfa.ru/alsha/node/2) [CRC64 parallel calculation](http://guildalfa.ru/alsha/node/4)

data-man commented

2017-10-31 13:00:29 +00:00

(Migrated from github.com)

A few words about Aleksandr Sharahov. See Fastcode Winner's List Overview

A few words about Aleksandr Sharahov. See [Fastcode Winner's List Overview](http://fastcode.sourceforge.net/challenge_content/Winners_List_Overview.html)

👍 1

tigrazone commented

2017-11-03 16:37:29 +00:00

(Migrated from github.com)

my hash function is simpler and faster
function thrHashKey(const Key:TBESENString):TBESENHash;
var i,h:longword;
begin
if length(key)<1 then
begin
result:=0;
exit;
end;

h:=ord(Key[1]);
for i:=2 to length(Key) do begin
h:=(h shl 5) - h + ord(Key[i]);
end;

result:=h;
end;

my hash function is simpler and faster function thrHashKey(const Key:TBESENString):TBESENHash; var i,h:longword; begin if length(key)<1 then begin result:=0; exit; end; h:=ord(Key[1]); for i:=2 to length(Key) do begin h:=(h shl 5) - h + ord(Key[i]); end; result:=h; end;

data-man commented

2017-11-03 16:58:57 +00:00

(Migrated from github.com)

@tigrazone
Why do you call it your function?
It is called X31Hash and it was invented by Karl Nelson more than 17 years ago.

@tigrazone Why do you call it your function? It is called X31Hash and it was invented by Karl Nelson more than 17 years ago.

tigrazone commented

2017-11-03 17:14:17 +00:00

(Migrated from github.com)

yes! it's X31Hash. same function used in TFPHashList
Function FPHash(const s:shortstring):LongWord;
var
p,pmax : PChar;
begin
{$push}
{$Q-}
Result:=0;
p:=@s[1];
pmax:=@s[length(s)+1];
while (p<pmax) do
begin
Result:=LongWord(LongInt(Result shl 5) - LongInt(Result)) xor LongWord(P^);
Inc(p);
end;
{$pop}
end;

yes! it's X31Hash. same function used in TFPHashList Function FPHash(const s:shortstring):LongWord; var p,pmax : PChar; begin {$push} {$Q-} Result:=0; p:=@s[1]; pmax:=@s[length(s)+1]; while (p<pmax) do begin Result:=LongWord(LongInt(Result shl 5) - LongInt(Result)) xor LongWord(P^); Inc(p); end; {$pop} end;

data-man commented

2017-11-03 17:51:59 +00:00

(Migrated from github.com)

Well, then the FP developers also do not respect the merits and work of other people.
This is not accepted in the open source community.
Honest people are not accepted that way.
And you had impudence to name a function by your name.

@BeRo1985 don't merge this PR, please.

Well, then the FP developers also do not respect the merits and work of other people. This is not accepted in the open source community. Honest people are not accepted that way. And you had impudence to name a function by your name. @BeRo1985 don't merge this PR, please.

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