LEA

[bomz]

The main - how use LEA right. Now I'm measured my last code in dedndave ticks count program and optimize it

Itanium 2 (2002+), MMX, SSE2
1233 1227 1229 1235 1230 - empty
8872 8886 8885 8897 8877 - mov eax, value; mov value, eax
14120 14121 14118 14119 14119 - push value; pop value
Press any key to continue ...

[hutch--]

bomz,

Try a few of these and you can experiment with more.

Code Select Expand


    lea eax, [eax+eax]      ; *2
    lea eax, [eax+eax*2]    ; *3
    lea eax, [eax*4]        ; *4
    lea eax, [eax+eax*4]    ; *5

    lea eax, [eax+eax*2]    ;
    lea eax, [eax+eax]      ; *6

    mov ecx, eax
    lea eax, [eax*8]        ; *7
    sub eax, ecx

    lea eax, [eax*8]        ; *8
    lea eax, [eax+eax*8]    ; *9

    lea eax, [eax+eax*4]    ;
    lea eax, [eax+eax]      ; *10

    lea eax, [eax+eax*2]    ;
    lea eax, [eax*4]        ; *12

    lea eax, [eax+eax*4]    ;
    lea eax, [eax+eax*2]    ; *15

    lea eax, [eax*4]        ;
    lea eax, [eax*4]        ; *16

    lea eax, [eax+eax*8]    ;
    lea eax, [eax+eax]      ; *18


[bomz]

Itanium 2 (2002+), MMX, SSE2
1231 1231 1229 1226 1229 - empty
5027 5028 5026 5027 5027 - lea eax, [eax+eax*2]; lea eax, [eax+eax]
5027 5027 5027 5027 5027 - lea edx, [eax+eax*2]; lea eax, [edx+edx]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1228 1234 1231 1231 1230 - empty
5027 5028 5027 5027 5027 - lea eax, [eax+eax*2]; lea eax, [eax+eax]
5033 5032 5033 5032 5032 - mov edx, eax; lea edx, [edx+eax*2] ;lea eax, [edx+edx]      ; *6
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1228 1226 1227 1227 1231 - empty
5028 5028 5028 5026 5026 - lea eax, [eax+eax*2]; lea eax, [eax+eax]
5663 5662 5659 5665 5663 - mov ecx, eax; lea edx, [ecx+eax*2]; mov ecx, edx; lea eax, [ecx+edx]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1234 1228 1228 1234 1229 - empty
5028 5028 5027 5026 5027 - lea eax, [eax+eax*2]; lea eax, [eax+eax]
10064 10064 10065 10064 10064 -  mov edx, eax; shl eax, 1; add eax, edx; shl eax, 1
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1229 1226 1230 1229 1229 - empty
5028 5028 5028 5027 5027 - lea eax, [eax+eax*2]; lea eax, [eax+eax]
9067 9067 9068 9069 9068 - lea edx, [eax+eax*2]; lea eax, [edx*2]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1236 1232 1253 1225 1234 - empty
1497 1511 1496 1494 1502 - lea     edx,[4*eax+eax]
3997 3995 3997 3996 3996 - lea     eax,[4*eax+eax]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1226 1226 1234 1229 1235 - empty
8053 8056 8057 8054 8053 - lea eax, [4*EAX+EAX]; add edx, 1; lea eax, [2*EAX+ECX]
8052 8051 8051 8051 8049 - lea ebx, [4*EAX+EAX]; add edx, 1; lea eax, [2*EBX+ECX]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1227 1231 1228 1238 1233 - empty
8054 8056 8053 8054 8053 - lea eax, [4*EAX+EAX]; lea eax, [4*EAX+EAX]
2109 2111 2111 2113 2112 - lea eax, [4*EBX+ECX]; lea eax, [4*EDX+EDI]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1233 1225 1238 1226 1226 - empty
8058 8064 8059 8055 8054 - lea eax, [4*EAX+EAX]; lea eax, [2*EAX+ECX]
8052 8049 8052 8055 8049 - lea eax, [4*EAX+EAX]; lea ebx, [esi+edi]; lea eax, [2*EAX+ECX]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1233 1224 1232 1230 1239 - empty
8054 8057 8057 8054 8054 - lea eax, [4*EAX+EAX]; lea eax, [2*EAX+ECX]
8051 8053 8060 8051 8054 - lea eax, [4*EAX+EAX]; lea ebx, value; lea eax, [2*EAX+ECX]
Press any key to continue ...

Itanium 2 (2002+), MMX, SSE2
1229 1236 1231 1232 1239 - empty
8056 8057 8055 8055 8054 - lea eax, [4*EAX+EAX]; lea eax, [2*EAX+ECX]
9058 9058 9058 9058 9058 - lea ebx, [4*EAX+EAX]; mov edx, ebx; lea eax, [2*EDX+ECX]
Press any key to continue ...

[hutch--]

bomz,

An Itanium 2 is not a native x86 architecture, are you running an Itanium in x86 emulation mode ?

[bomz]

Itanium 2 (2002+), MMX, SSE2
1228 1228 1229 1231 1230 - empty
8054 8057 8055 8053 8053 - lea eax, [4*EAX+EAX]; lea eax, [2*EAX+ECX]
4034 4034 4034 4034 4034 - lea eax, [4*EAX+EAX]; mov ebx, eax; lea ebx, [2*EBX+ECX]
Press any key to continue ...

[bomz]

I have Pentium 4. Program recognize it like Itanium I don't know why

Itanium 2 (2002+), MMX, SSE2
1227 1234 1230 1230 1226 - empty
8062 8070 8062 8063 8114 - lea eax, [4*EAX+EAX]; lea eax, [2*EAX+ECX]
9063 9062 9058 9059 9057 - lea eax, [4*EAX+EAX]; mov ebx, eax; lea eax, [2*EBX+ECX]
Press any key to continue ...

I am not already catch regularity

lea ebx, [4*EAX+EAX]
   mov edx, ebx
   lea ebx, [2*EDX+ECX]

- 3000

[hutch--]

Your OS is giving the correct processor ID, its a Northwood core PIV, not an Itanium. An Itanium is a 64 bit native processor with a different instruction set. They are mainly useful for large processor count parallel processing. I still have a 2.8 gig Northwood processor running and they were a bit easier to code for than the later Prescott cores.

[bomz]

I begin testing all code string-to-dword. there is no difference use lea or not. any combination of registers gives the same result to convert 100 to 100 need about 18000 program ticks

[dedndave]

convert 100 to 100 need about 18000 program ticks

ouch !!!!

bomz - don't be concerned about the improper CPU identification
it is an old version of Jochen's ShowCpu function   :P

[bomz]

need 18000 p ticks for doing it 1000 times  :lol

lea ebx, [4*EAX+EAX]
   mov edx, ebx
   lea ebx, [2*EDX+ECX] this need 3000 but when put in s2w cycle it became 8000

[jj2007]

bomz - don't be concerned about the improper CPU identification
it is an old version of Jochen's ShowCpu function   :P

Bomz, what CPU does it show with the attachment of reply #50?

[bomz]

with the attachment of reply #50?  - ???????????????

[dedndave]

reply #50...

http://www.masm32.com/board/index.php?topic=16988.msg141804#msg141804

[bomz]

[bomz]

   lea ebx, [4*EAX+EAX]
   mov edx, ebx
   lea ebx, [2*EDX+ECX]  - 3000

   lea ebx, [4*EAX+EAX]
   mov edx, ebx
   lea ebx, [2*EDX+ECX]
   mov eax, ebx - 10000