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Speed of ASM Instructions ...(comparison of different implementations)
Posted: Wed Dec 14, 2022 12:48 pm
by Axolotl
Hi folks,
I am doing some memory analysing stuff and was wondering about the best implementation.
Code: Select all
; === Test Program -- Compare implementations ===
Structure TByteArray ; Memory Access by *Memory\Byte[Index]
Byte.a[0]
EndStructure
Procedure Test_1(*M, Index)
Protected r
r = PeekA(*M + Index)
Debug "1:" + r + " | " + Index
EndProcedure
Procedure Test_2(*Mem.TByteArray, Index)
Protected r
r = *Mem\Byte[Index]
Debug "2:" + r + " | " + Index
EndProcedure
*MemoryID = AllocateMemory(500)
If *MemoryID
Debug "Starting address of the 500 Byte memory area:"
PokeS(*MemoryID, "ABC Store this string in the memory area", -1, #PB_Ascii)
Test_1(*MemoryID, 1)
Test_2(*MemoryID, 1)
FreeMemory(*MemoryID) ; will also be done automatically at the end of program
Else
Debug "Couldn't allocate the requested memory!"
EndIf
This is what the ASM output shows: (I have prepared the part which is in my opinion the most important)
Code: Select all
; === Test 2 =========================================== Test 1 ===============================
;
; Structure TByteArray
; Byte.a[0]
; EndStructure
;
; Procedure Test_2(*Mem.TByteArray, Index) ; Procedure Test_1(*M, Index)
_Procedure2: _Procedure0:
MOV qword [rsp+8],rcx MOV qword [rsp+8],rcx
MOV qword [rsp+16],rdx MOV qword [rsp+16],rdx
PUSH rbp PUSH r15
PS2=64 PS0=64
XOR rax,rax XOR rax,rax
PUSH rax PUSH rax
SUB rsp,40 SUB rsp,40
; Protected r ; Protected r
; r = *Mem\Byte[Index] ; r = PeekA(*M + Index)
MOV rbp,qword [rsp+PS2+0] MOV r15,qword [rsp+PS0+0]
PUSH rbp ADD r15,qword [rsp+PS0+8]
MOV rax,qword [rsp+PS2+16] MOV rax,r15
POP rbp PUSH rax
ADD rbp,rax POP rcx
MOVZX rax,byte [rbp] CALL PB_PeekA
PUSH rax
POP rax
MOV qword [rsp+40],rax MOV qword [rsp+40],rax
; ;
; Debug "2:" + r + " | " + Index ; Debug "1:" + r + " | " + Index
; EndProcedure ; EndProcedure
I would be interested in your opinion as ASM experts on this?
TIA.
Happy coding and stay healthy.
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Wed Dec 14, 2022 1:16 pm
by STARGÅTE
What is the question?
What is faster/better, Test_1 vs. Test_2?
Definitely Test_2 with the byte array, because you have no additional call instruction for PB_PeekA with jumps and you have to include the ASM output for PB_PeekA as well.
However, as you can see, the PB ASM output is not optimized, because of senseless lines like:
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Wed Dec 14, 2022 1:50 pm
by Axolotl
yes, you have extracted my question correctly...
sorry for writing so imprecisely.
I also suspected that the array could be faster.
Now I know.
thanks for your quick answer.
BTW: normally i don't dive that deep into assember code, but if you can....
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Wed Dec 14, 2022 11:59 pm
by idle
In General if you want to improve performance you just need to minimize branching and memory fetches
Also while loops are faster than for loops in PB and if you're processing strings, pass a string in by reference
This will compile to near optimal with C backend
Code: Select all
Structure TByteArray ; Memory Access by *Memory\Byte[Index]
Byte.a[0]
EndStructure
*MemoryID.TByteArray = Ascii("ABC Store this string in the memory area")
ct = 0
char.a
While *MemoryID\Byte[ct]
char = *MemoryID\Byte[ct]
debug chr(char)
ct+1
Wend
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Thu Dec 15, 2022 12:39 am
by mk-soft
Code: Select all
Structure ArrayOfAscII
Char.a[0]
EndStructure
Structure ArrayOfUnicode
Char.u[0]
EndStructure
Define Text.s
Define *pText.ArrayOfUnicode, *pAscII.ArrayOfAscII
Define index, char
Text = "ABC Store this string in the memory area"
*pText = @Text
*pAscII = Ascii(Text)
Debug "*** Unicode ***"
index = 0
While *pText\Char[index]
char = *pText\Char[index]
Debug RSet(Hex(char, #PB_Unicode), 4, "0") + ": " + Chr(char)
index + 1
Wend
Debug "*** AscII ***"
index = 0
While *pAscII\Char[index]
char = *pText\Char[index]
Debug RSet(Hex(char, #PB_Ascii), 2, "0") + ": " + Chr(char)
index + 1
Wend
FreeMemory(*pAscII)
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Thu Dec 15, 2022 12:56 am
by mk-soft
Code: Select all
Structure ArrayOfAscII
Char.a[0]
EndStructure
Structure ArrayOfUnicode
Char.u[0]
EndStructure
Define Text.s
Define *pText.ArrayOfUnicode, *pAscII.ArrayOfAscII
Define index, char
Text = "ABC Store this string in the memory area"
*pText = @Text
*pAscII = Ascii(Text)
Debug "*** Unicode ***"
index = 0
While *pText\Char[index]
char = *pText\Char[index]
Debug RSet(Hex(char, #PB_Unicode), 4, "0") + ": " + Chr(char)
index + 1
Wend
Debug "*** AscII ***"
index = 0
While *pAscII\Char[index]
char = *pText\Char[index]
Debug RSet(Hex(char, #PB_Ascii), 2, "0") + ": " + Chr(char)
index + 1
Wend
FreeMemory(*pAscII)
Debug "*** String Parameter ByRef / Need always a variable 'strVal' of type string where store pointer to string ***"
Procedure Upper(*string.string)
*string\s = "+++ " + UCase(*string\s) + " +++"
ProcedureReturn Len(*string\s)
EndProcedure
Define len, strVal.String
strVal\s = "hello world"
Debug "Addr to string: " + @strVal\s
len = Upper(strVal)
Debug "Len = " + len + " / " + strVal\s
Debug "Addr to string: " + @strVal\s
Re: Speed of ASM Instructions ...(comparison of different implementations)
Posted: Thu Dec 15, 2022 11:24 am
by juergenkulow
Code: Select all
; movzx eax, byte [rdx+rax]
Structure TByteArray
Byte.a[0]
EndStructure
*MemoryID.TByteArray=Ascii("ABC Store this string in the memory area")
! asm("nop");
Index=1
r1=PeekA(*MemoryID + Index)
r2=*MemoryID\Byte[Index]
! asm("nop");
Debug r1
Debug r2
CompilerIf #PB_Compiler_Backend<>#PB_Backend_C Or #PB_Compiler_Optimizer=0
CompilerError "Please switch Copmpiler to opimized C Backend."
CompilerEndIf
; 66
; 66
; 0000000140001086 | 48:C705 2F330000 0100000 | mov qword ptr ds:[1400043C0],1 |
; 0000000140001091 | 48:8B0D 28330000 | mov rcx,qword ptr ds:[1400043C0] |
; 0000000140001098 | 48:030D 29330000 | add rcx,qword ptr ds:[1400043C8] |
; 000000014000109F | E8 9C040000 | call memtest2.140001540 |
; 00000001400010A4 | 48:8905 2D330000 | mov qword ptr ds:[1400043D8],rax |
; 00000001400010AB | 48:8B05 0E330000 | mov rax,qword ptr ds:[1400043C0] |
; 00000001400010B2 | 48:8B15 0F330000 | mov rdx,qword ptr ds:[1400043C8] | rdx:EntryPoint
; 00000001400010B9 | 0FB60402 | movzx eax,byte ptr ds:[rdx+rax] |
; 00000001400010BD | 48:8905 0C330000 | mov qword ptr ds:[1400043D0],rax |
Code: Select all
; Test(*MemoryID, Index)
*MemoryID=Ascii("ABC Store this string in the memory area")
Index=1
Define r.q
EnableASM
mov rdx,[v_Index]
mov rax,[p_MemoryID]
movzx eax, byte [rdx+rax]
mov [v_r],rax
DisableASM
Debug r
CompilerIf #PB_Compiler_Backend<>#PB_Backend_Asm
CompilerError "Please switch Copmpiler to ASM Backend."
CompilerEndIf