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Why is there a bunch of NOPs after JNE?

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gir489
Grandmaster Cheater

Reputation: 14

Joined: 03 Jan 2012
Posts: 841
Location: Maryland, United States

Posted: Sun Mar 31, 2019 11:28 am Post subject: Why is there a bunch of NOPs after JNE?

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If I do something like this in a 64-bit script:

Code:

cmp [rsp],PreyDll.dll+2E75038
jne notwidth
mov [rax+04],(float)8
notwidth:

I get this:

Code:

7FFDD1910000 - 81 3C 24 38507AD4 - cmp [rsp],D47A5038 { -730181576 }
7FFDD1910007 - 75 0B - jne 7FFDD1910014
7FFDD1910009 - 90 - nop
7FFDD191000A - 90 - nop
7FFDD191000B - 90 - nop
7FFDD191000C - 90 - nop
7FFDD191000D - C7 40 04 00000041 - mov [rax+04],41000000 { 8.00 }
7FFDD1910014 - 81 3C 24 30507AD4 - cmp [rsp],D47A5030 { -730181584 }

Why? Why is there 4 NOPs added? Can I tell the assembler not to do that somehow?

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ParkourPenguin
I post too much

Reputation: 152

Joined: 06 Jul 2014
Posts: 4699

Posted: Sun Mar 31, 2019 12:24 pm Post subject:

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CE has no idea how far away the destination is at the time of that instruction, so it assumes the instruction will take up more memory than is actually needed.

Override it with short

Code:

jne short notwidth

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I don't know where I'm going, but I'll figure it out when I get there.

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Dark Byte
Site Admin

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Joined: 09 May 2003
Posts: 25788
Location: The netherlands

Posted: Sun Mar 31, 2019 1:24 pm Post subject:

next ce version will just place a 6 byte jne there (unless overriden) _________________ Do not ask me about online cheats. I don't know any and wont help finding them. Like my help? Join me on Patreon so i can keep helping

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