no-op Questions

15

Solved

I searched for noop in bash (:), but was not able to find any good information. What is the exact purpose or use case of this operator? I tried following and it's working like this for me: [mandy...
Icao asked 13/9, 2012 at 10:55

5

Solved

Sometimes when making conditionals, I need the code to do nothing, e.g., here, I want Bash to do nothing when $a is greater than "10", print "1" if $a is less than "5", otherwise, print "2": if [ ...
Frayne asked 11/7, 2013 at 1:24

12

Solved

One in a while there's a need for a no-op statement in C++. For example when implementing assert() which is disabled in non-debug configuration (also see this question): #ifdef _DEBUG #define asse...
Pearce asked 2/11, 2011 at 10:10

1

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If you compile code such as #include <atomic> int load(std::atomic<int> *p) { return p->load(std::memory_order_acquire) + p->load(std::memory_order_acquire); } you see that MSV...
Baribaric asked 30/12, 2022 at 0:40

4

Solved

Venturing out of my usual VC++ realm into the world of GCC (via MINGW32). Trying to create a Windows PE that consists largely of NOPs, ala: for(i = 0; i < 1000; i++) { asm("nop"); } ...
Moxa asked 31/12, 2010 at 0:5

18

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What is a simple Noop statement in C#, that doesn't require implementing a method? (Inline/Lambda methods are OK, though.) My current use case: I want to occupy the catch-block of a try-catch, so...
Falciform asked 3/8, 2011 at 10:7

5

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In linux we have a makefile: $(foreach A,a b,echo $(A) &&) true It works and echos a b Now we want to port it to Windows. The shortest command I've found for Windows that does nothing...
Underbody asked 25/8, 2011 at 12:41

3

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Sometimes I do not want to do anything. I just want to have a statement so I can put break point. In c and objective-c we have while (false); Say I want to break a function -(void)viewDidAppear...
Spoilage asked 9/1, 2013 at 9:0

1

It's not a big secret that x86 (and x86_64) processors have not only the single-byte NOP instruction, but also various types of multi-byte NOP-like instructions. These are the ones I've managed to...
Tyrontyrone asked 28/8, 2014 at 9:35

3

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I'm trying to understand the x64 assembly optimization that is done by the compiler. I compiled a small C++ project as Release build with Visual Studio 2008 SP1 IDE on Windows 8.1. And one of the...
Susannsusanna asked 16/5, 2017 at 1:29

4

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In my Angular 6 application, I need a function that does nothing. Obviously, I could just write my own, but I was reading about angular.noop which I would like to use. However, I get an angular.noo...
Jahn asked 12/10, 2018 at 15:48

4

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My guess is that the __no_operation() intrinsic (ARM) instruction should take 1/(168 MHz) to execute, provided that each NOP executes in one clock cycle, which I would like to verify via documenta...
Sympathy asked 13/8, 2013 at 23:28

3

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I use KEIL to compile a program. The program uses the code asm("NOP"); Unfortunately KEIL compiler does not accept the statement. The idea is to introduce a delay by using NOP (no operation)...
Planimeter asked 10/9, 2014 at 10:17

3

I am working on RISC-V 32I instructions recently. I got a question about NOP instruction, which the specification says it is equal to ADDI x0, x0, 0. However, x0 is not a general register which ca...
Tull asked 12/6, 2018 at 18:46

1

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Why was nop assigned to 0x90 on intel x86 assembly? Intuitively I would expect that 0x00 would map to nop (which is also xchg eax, eax at intel x86) as it is the case for ARM A32 and some other ar...
Unready asked 1/5, 2019 at 19:54

1

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I was wondering what people suggest when working with optional default functions in React. I have seen our codebase use a mix of () => {} and the lodash noop. Which is preferable? This is a gen...
Conch asked 21/1, 2019 at 19:43

1

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Is it possible to create a Cmd that sends no message on completion in Elm? Specifically, I am trying to have an element grab the focus (programmically), but I don't need to be informed of the resu...
Ezechiel asked 21/1, 2018 at 13:30

2

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I can't find a good source that answers this question. I know that a nop sled is a technique used to circumvent stack randomization in a buffer overflow attack, but I can't get my head around how i...
Thor asked 7/2, 2013 at 20:41

2

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I understand the error message: Type '() => void' is not assignable to type '() => {}' Well sort of, it is telling me there is a type casting issue. However I can't work out why the compiler t...
Grammarian asked 28/7, 2017 at 8:21

3

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I'm aligning branch targets with NOPs, and sometimes the CPU executes these NOPs, up to 15 NOPs. How many 1-byte NOPs can Skylake execute in one cycle? What about other Intel-compatible processors,...
Little asked 11/7, 2017 at 17:24

4

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I am porting some code from an M3 to an M4 which uses 3 NOPs to provide a very short delay between serial output clock changes. The M3 instruction set defines the time for a NOP as 1 cycle. I notic...
Contextual asked 12/5, 2014 at 14:52

1

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Given the following C function: void go(char *data) { char name[64]; strcpy(name, data); } GCC 5 and 6 on x86-64 compile (plain gcc -c -g -o followed by objdump) this to: 0000000000000000 &lt...
Logographic asked 15/4, 2016 at 11:55

1

As a small recall, the x86 architecture defines 0x0F 0x1F [mod R/M] as a multi-byte NOP. Now I'm looking at the specific case of an 8-byte NOP: I have got 0x0F 0x1F 0x84 0x__ 0x__ 0x__ 0x__ 0x__ ...
Nomarchy asked 31/12, 2014 at 0:21

2

Why #define assert(expression) ((void)0), rather than #define assert(expression) is used in release mode?(strictly speaking, when NDEBUG is defined) I heard that there are some reasons, but I've...
Stable asked 31/3, 2016 at 9:23

3

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Are there any practical uses of the Java Virtual Machine's NOP opcode in today's JVM? If so, what are some scenarios in which NOPs would be generated in bytecode? I would even be interested to see...
Cove asked 2/5, 2012 at 21:36

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