Conditional jump or move depends on uninitialised value s как исправить

The conditional jump or move depends on uninitialised value(s) error can be fixed by initializing the word inside the NULL function. This is a common problem web developers face where this jump is going to affect the rest of the document and render it incorrectly.

We are going to provide thorough explanations and examples to teach you how you can easily fix this problem. Keep reading the following sections of this article to understand the main reason for this error.

Why Is the Conditional Jump or Move Depends on Uninitialised Value(s) Error Happening?

This error in the code is happening due to uninitialized values inside the structure that are introduced by the temp function. You are going to receive this error message if you try to check whether the NULL function has a specific value though you have not included the initialized values inside the temp function.

The current jump or move depends on uninitialised value(s), also known as a Valgrind error, and will affect the rest of your document. However, we are going to show you a way you can fix this error with a simple change of the code. As this is one of the main challenges once working with programming languages, you should not be worried because we are going to provide all the necessary answers.

How To Fix This Valgrind Error?

Fixing this error in your document is done by initializing the word form inside the NULL function. In theory, this sounds like an easy fix, but you first must learn about the structure of the complete error message. For example, the current jump or move depends on the uninitialized value(s), which is just a fraction of the complete error syntax, and you should know what is happening.

– Code Example 1:

The following example is going to show you how the complete error syntax looks like:

==11365== Current jump or move depends on uninitialised value(s)
==11365== at 0x43CAE4F: __printf_fp (in /lib/tls/i686/cmov/libc-2.7.so)
==11365== by 0x43C6163: vfprintf (in /lib/tls/i686/cmov/libc-2.7.so)
==11363== by 0x43EBC03: vsnprintf (in /lib/tls/i686/cmov/libc-2.7.so)
==11362== by 0x42D475B: (within /usr/lib/libstdc++.so.6.0.9)
==11367== by 0x41E2C9B: std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, char, double) const (in /usr/lib/libstdc++.so.6.0.9)
==11366== by 0x42E31B4: std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::do_put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const (in /usr/lib/libstdc++.so.6.0.9)
==11366== by 0x42EE56F: std::ostream& std::ostream::_M_insert<double>(double) (in /usr/lib/libstdc++.so.6.0.9)
==11366== by 0x42EE56F: std::ostream& std::ostream::_M_insert<double>(double) (in /usr/lib/libstdc++.so.6.0.9)
==11366== by 0x81109ED: Snake::SnakeBody::syncBodyPos() (ostream:221)
==11366== by 0x810B9F1: Snake::Snake::update() (snake.cpp:257)
==11366== by 0x81113C1: SnakeApp::updateState() (snakeapp.cpp:224)
==11366== by 0x8120351: RoenGL::updateState() (roengl.cpp:1180)
==11366== by 0x81E87D9: Roensachs::update() (rs.cpp:321)

If the following looks complicated, do not fear because we are going to provide a simple solution. As you can see, the first line of code in this example states the error but what follows is the complete problem. Let us now see how easy it is to fix this syntax.

– Providing the Code That Fixes Conditional Jump or Move Depending on Uninitialised Value(s)

Since you know a lot more about this jump error and what the complete syntax looks like, it is time to change the values and fix the issue. You are supposed to include the Valgrind value at the beginning of the code and include all necessary functions.

– Code Example 2: Fixing the Error

Let us take a closer look at the following example that contains the solution:

valgrind –num-callers=30 –log-file=valgrind.txt –gen-suppressions=all –error-limit=no –suppressions=$ROOTSYS/etc/valgrind-root.supp
root.exe -l -q -e ‘std::cout << “hello everyonen”;’

As you can see, the solution to this error is much shorter than the complete error syntax. The NUM function has the appropriate value, and the rest of the code is going to fix other bugs and rendering problems. This newly created node is the best solution to the problem. Before we learn more about Valgrind and how it is implemented to fix errors, let us learn some important points about the process of fixing this error.

Important Notes: Current Jump or Move Depends on Uninitialized Value(s)

Working on various errors in your syntax is a process that consists of several steps. Also, you should be aware that there are some important points you should know about the error discussed in this article. Take a closer look at the following bullet list to learn the important points that are going to make the process of debugging much easier:

• Any ASCII value that is less than 97 is going to return a negative value inside the argument by the has function if there are no uppercase characters.

• The highest possible value of the hash function is 25 if we assume there are only alphabetical characters and apostrophes. Consequently, you are only going to need 26 buckets in the array.

• It is not obligatory to assign memory for each bucket in the array.

• The word value can be allocated as a charset and manually included inside the memory of the heap.

• You do not have to use the oneword and tempword functions to read the value. Locate the word function, and the value is going to be there.

• The assignment operator is going to take the right expression and assign the variable value on the left.

It is important to be aware of these notes to understand the error’s meaning better. Also, these points are going to help you easily fix the error by changing the syntax. Since Valgrind is such an important factor during the process of debugging, let us learn something more about it.

Learning More About Valgrind for Debugging

Valgrind is an assistive tool for debugging and fixing errors once working with various programs. You can use this tool to easily locate the error and take all the necessary steps to fix it immediately. Furthermore, running this tool can be easily included inside the program.

– Code Example 3

We are going to show you a simple line of code that captures the essence of this assistive tool.

valgrind –tool=memcheck –leak-check=yes ./program

This simple line of code is all it takes to implement Valgrind inside your program. To better capture what this tool is capable of, we are going to show you some of the most common bugs that can be fixed. Keep reading the following section of this article, where we explain and exemplify some of the most common bugs.

– Losing X Bytes and Y Blocks

This common error represents a memory loss that may show up while you are using the program. It represents one of the most common errors, and it consists of a couple of lines of code.

– Code Example 4

The following syntax shows us how this error may look if it appears in your program:

8 bytes in 1 block are complete lost in loss record 1 of 7
at 0x581C344: operator new[](unsigned long) (vg_replace_malloc.c:413)
by 0x1091CB: main (valgrind-test.cpp:5)

This error pops up immediately after conducting a Valgrind test for your program and the complete syntax. The following example shows the reason why this code may appear, so take a closer look:

int ** matrix = new int*[1];
matrix[9] = new int[1]; // error points where memory was allocated
delete [] matrix;

Now that you know something more about the reason for the problem, let us see how you can fix it.

– Code Example 5

It does not take a lot of work and effort to fix the error, as you can see from the following example:

==5218== Current jump or move depends on uninitialised value(s)
==5218== at 0x401968: ListTest::~ListTest() (listtest.cpp:20)
==5218== by 0x401728: main (in /home/test)
==5218== Uninitialised value was created by a heap allocation <=== PAY ATTENTION TO THESE NOTES
==5218== at 0x4C3E89F: operator new[](unsigned long)
==5218== by 0x4028EF: ListTest::ListTest() (listtest.cpp:8)
==5218== by 0x40526D: main (in /home/test)

This example wraps everything about the losing x bytes error. Let us move on to the next one.

– Invalid Read or Write of the X Value

Another common error that appears is the invalid read or write of the x value inside your program. This may happen due to a deleted memory that has been tried to be accessed again in any way. Moreover, Valgrind is going to locate the error and tell you which part of the memory originally contained this content.

– Code Example 6

Let us take a closer at the following syntax that contains an error example:

Invalid read of size 8
at 0x10922C: main (valgrind-test.cpp:17)
Block was alloc’d at
by 0x1091D9: main (valgrind-test.cpp:7)
Invalid write of size 4
at 0x10922F: main (valgrind-test.cpp:17)
Address 0x0 is not stack’d, malloc’d or (recently) free’d

As with the previous example, knowing what caused this problem is important. There are only several lines of code that will clarify the reason for the error and specify what went wrong.

– Code Example 7

The following example contains those lines of code:

This example wraps up everything important you were supposed to know about Valgrind and how it can help you fix specific bugs inside your program. Now you know a lot more about the steps it takes to fix an error that appears in your syntax. Let us now summarize some of the most important points.

Summary

The conditional jump or move depends on an uninitialised value(s) error that can be fixed by initializing the word inside the NULL function. Besides teaching you how to debug this error inside your program properly, this article also covered the following important points:

• The NULL function is one of the most important functions inside your syntax, and it makes a huge difference in the execution of the code
• The error message usually consists of several lines of code instead of a single line
• There are several important notes you should know about this error and the way you can fix it
• Valgrind is always used to locate and fix a specific error inside your program and can be used in various situations

If you thought that fixing this error is a long and painful process, you are wrong. This article was the best place to learn what it takes to debug your program and make it functional once again completely.

If you are getting trouble with the error “Conditional jump or move depends on uninitialised value(s)”, don’t worry and keep calm, then follow our article to know how to deal with it.

Reason for The ERROR “conditional jump or move depends on the uninitialized value(s)“

In C++, when you use a variable which has been initialised, you may get the result 0 or a number corresponding to the memory. In fact, this error is not reported by the compiler. It is detected by “Valgrind” tool.

Example:

#include <bits/stdc++.h>
using namespace std;
 
int main()
{
 int n;
 int arr[n+1];
 int sum=0;

 for(int i=1; i<=n; i++){
   arr[i] = i;
   sum += arr[i];
 }

 cout << sum << endl;
}

Then, run the following commands in your terminal :

g++ -g example.cpp 
valgrind ./a.out

Result:

==20423== Memcheck, a memory error detector
==20423== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==20423== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==20423== Command: ./a.out
==20423== 
==20423== Conditional jump or move depends on uninitialised value(s)
==20423==    at 0x109259: main (example.cpp:8)
==20423== 
==20423== Conditional jump or move depends on uninitialised value(s)
==20423==    at 0x109285: main (example.cpp:8)
==20423== 
==20423== Use of uninitialised value of size 8
==20423==    at 0x109293: main (example.cpp:8)
==20423== 
==20423== Conditional jump or move depends on uninitialised value(s)
==20423==    at 0x1092BE: main (example.cpp:10)
==20423== 
==20423== Use of uninitialised value of size 8
==20423==    at 0x1092F2: main (example.cpp:14)
==20423== 
==20423== Use of uninitialised value of size 8
==20423==    at 0x48F4044: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.28)
==20423== 
0
==20423== 
==20423== HEAP SUMMARY:
==20423==     in use at exit: 0 bytes in 0 blocks
==20423==   total heap usage: 2 allocs, 2 frees, 73,728 bytes allocated
==20423== 
==20423== All heap blocks were freed -- no leaks are possible
==20423== 
==20423== Use --track-origins=yes to see where uninitialised values come from
==20423== For lists of detected and suppressed errors, rerun with: -s
==20423== ERROR SUMMARY: 6 errors from 6 contexts (suppressed: 0 from 0)

Solutions to solve this problem

Remember that this error results from using a variable without an initial value. So, the solution for this error turns out to be simple. The only thing you have to do is find the variable and give it a value.

Code:

#include <bits/stdc++.h>
using namespace std;
 
int main()
{
 int n;
 n = 22;
 int arr[n+1];
 int sum=0;

 for(int i=1; i<=n; i++){
   arr[i] = i;
   sum += arr[i];
 }

 cout << sum << endl;
}

Result:

253

Summary

Conditional jump or move depends on uninitialised value(s) caused by using a variable that is forgotten to declare initial value is very common, which leads to unexpected results. Through our article, I hope you understand the error clearly and never forget to define variables.

Maybe you are interested:

• Print a vector in C++
• How To Split String By Space In C++
• Error: lvalue required as left operand of assignment

Если вы пишете код на языке C или C++, поиск и устранение ошибок работы с памятью, таких, как утечки, выход за границы массива или обращение к неинициализированной памяти, могут доставить немало хлопот. Существует по крайней мере два инструмента для решения этих проблем — Valgrind (не путать с Vagrant!) и Clang’овский MemorySanitizer. Последний работает исключительно под Linux и показал себя несколько сырым и не слишком гибким инструментом, поэтому поговорим о Valgrind. Он довольно гибок и работает везде. Кроме того, в отличие от MemorySanitizer, Valgrind может находить неинициализированные данные с точностью до одного бита. Из недостатков Valgrind стоит отметить сравнительно низкую скорость работы.

Простой пример

Перейдем сразу к делу и проверим работу Valgrind на такой программе:

Компилируем с отладочными символами и запускаем ее под Valgrind:

Результат:

Видим, что память утекла. Запускаем с --leak-check=full:

Теперь раскомментируем вызов free и уберем инициализацию переменной delta. Посмотрим, увидит ли Valgrind обращение к неинициализированной памяти:

Видит. Запустим с --track-origins=yes чтобы найти, откуда именно пришла неинициализированная переменаая:

Как видите, Valgrind нашел место объявления неинициализированной переменой с точностью до имени файла и номера строчки.

Теперь исправим все ошибки:

Ну разве не красота?

Пример посложнее — запускаем PostgreSQL под Valgrind

Рассмотрим, как происходит запуск под Valgrind больших программ, например, PostgreSQL. Работа с памятью в этой РСУБД устроена особым образом. Например, в ней используются иерархические пулы памяти (memory contexts). Для понимания всего этого хозяйства Valgrind’у нужны подсказки. Чтобы такие подсказки появились, нужно раскомментировать строчку:

… в файле src/include/pg_config_manual.h, после чего полностью пересобрать PostgreSQL. Затем запуск под Valgrind осуществляется как-то так:

Полный пример вы найдете в файле valgrind.sh из этого репозитория на GitHub.

Обратите внимание на флаг --leak-check=no. Даже с упомянутыми подсказками Valgrind все равно не подходит для поиска утечек памяти в PostgreSQL. Он попросту будет генерировать слишком много ложных сообщений об ошибках. Поэтому здесь Valgrind используется только для поиска обращений к неинициализированной памяти.

Флаг --trace-children=yes в приведенной выше команде, как несложно догадаться, говорит Valgrind’у цепляться к процессам-потомкам.

Еще стоит отметить флаг --suppressions, который задает файл с описанием ошибок, которые следует игнорировать, а также флаг --gen-suppressions=all, который в случае возникновения ошибок генерирует строки, которые можно добавить в этот самый файл для игнорирования ошибок. Кстати, в файле можно использовать wildcards, в стиле:

В зависимости от используемых флагов, make installcheck под Valgrind’ом на моем ноутбуке выполняется от получаса до часа. Для сравнения, без Valgrind’а соответствующий прогон тестов занимает порядка 3.5 минут. Отсюда можно сделать вывод, что программа под Valgrind выполняется в 10-20 раз медленнее.

Использование Valgrind совместно с GDB

Посмотрев на приведенные выше отчеты Valgrind’а об ошибках, можно заметить, что в определенном смысле они недостаточно информативны. В частности, в них нет имен переменных и информации о том, какие конкретно данные в них лежали на момент возникновения ошибки. Решается эта проблема запуском Valgrind’а с флагами:

Эти флаги говорят Valgrind остановить процесс и запустить gdb-сервер после возникновения первой ошибки. Можно указать и --vgdb-error=0, чтобы подключиться к процессу отладчиком сразу после его запуска. Однако это может быть плохой идеей, если вы также указали --trace-children=yes и при этом программа создает множество дочерних процессов.

При возникновении ошибки Valgrind напишет:

После этого, чтобы подключиться к процессу при помощи GDB, говорим:

… и уже в отладчике:

Из интересных дополнительных команд доступны следующие. Посмотреть список утечек:

Узнать, кто ссылается на память:

Проверка инициализированности памяти (0 — бит инициализирован, 1 — не инициализирован, _ — not addressable):

Прочее:

Дальше отлаживаем, как обычно. Например, говорим continue. Как только произойдет следующая ошибка, программа снова остановится по брейкпоинту. Можно смотреть значения переменных, перемещаться между фреймами стека, ставить собственные брейкпоинты, и так далее.

Заключение

К сожалению, в рамках одного поста невозможно рассмотреть абсолютно все возможности Valgrind. Например, в него входят инструменты Callgrind и Massif, предназначенные для поиска узких мест в коде и профилирования памяти соответственно. Эти инструменты я не рассматриваю, так как для решения названных задач предпочитаю использовать perf и Heaptrack. Также существует инструмент Helgrind, предназначенный для поиска гонок. Его изучение я вынужден оставить вам в качестве упражнения.

Как видите, пользоваться Valgrind крайне просто. Он, конечно, не идеален. Как уже отмечалось, Valgrind существенно замедляет выполнение программы. Кроме того, в нем случаются ложноположительные срабатывания. Однако последняя проблема решается составлением специфичного для вашего проекта файла подавления конкретных отчетов об ошибках. Так или иначе, если вы пишете на C/C++ и не прогоняете код под Valgrind хотя бы в Jenkins или TeamCity незадолго до релиза, вы явно делаете что-то не так!

А как вы ищете утечки и обращения к неинициализированной памяти?

Метки: C/C++, Отладка.

0

0

при обновлении системы valgrind теперь матерится на любое приложение, что очень неудобно при отладке, как это исправить?
==11482== Memcheck, a memory error detector.
==11482== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==11482== Using LibVEX rev 1732, a library for dynamic binary translation.
==11482== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==11482== Using valgrind-3.2.3, a dynamic binary instrumentation framework.
==11482== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==11482== For more details, rerun with: -v
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x4015411: (within /lib/ld-2.6.1.so)
==11482==    by 0x4007C9E: (within /lib/ld-2.6.1.so)
==11482==    by 0x4003694: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x401541C: (within /lib/ld-2.6.1.so)
==11482==    by 0x4007C9E: (within /lib/ld-2.6.1.so)
==11482==    by 0x4003694: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400A939: (within /lib/ld-2.6.1.so)
==11482==    by 0x400452C: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400A941: (within /lib/ld-2.6.1.so)
==11482==    by 0x400452C: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400ADF9: (within /lib/ld-2.6.1.so)
==11482==    by 0x400452C: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400AA84: (within /lib/ld-2.6.1.so)
==11482==    by 0x400452C: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400A939: (within /lib/ld-2.6.1.so)
==11482==    by 0x400414A: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400A941: (within /lib/ld-2.6.1.so)
==11482==    by 0x400414A: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x400AA84: (within /lib/ld-2.6.1.so)
==11482==    by 0x400414A: (within /lib/ld-2.6.1.so)
==11482==    by 0x4013B15: (within /lib/ld-2.6.1.so)
==11482==    by 0x400124E: (within /lib/ld-2.6.1.so)
==11482==    by 0x40008A6: (within /lib/ld-2.6.1.so)
==11482== 
==11482== Use of uninitialised value of size 4
==11482==    at 0x4075E09: (within /lib/libc-2.6.1.so)
==11482==    by 0x4079AA1: vfprintf (in /lib/libc-2.6.1.so)
==11482==    by 0x407F9F2: printf (in /lib/libc-2.6.1.so)
==11482==    by 0x804932F: main (in /home/ary/src/gcmd/src/backend/a.out)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x4075E11: (within /lib/libc-2.6.1.so)
==11482==    by 0x4079AA1: vfprintf (in /lib/libc-2.6.1.so)
==11482==    by 0x407F9F2: printf (in /lib/libc-2.6.1.so)
==11482==    by 0x804932F: main (in /home/ary/src/gcmd/src/backend/a.out)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x4077B16: vfprintf (in /lib/libc-2.6.1.so)
==11482==    by 0x407F9F2: printf (in /lib/libc-2.6.1.so)
==11482==    by 0x804932F: main (in /home/ary/src/gcmd/src/backend/a.out)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x4079C66: vfprintf (in /lib/libc-2.6.1.so)
==11482==    by 0x407F9F2: printf (in /lib/libc-2.6.1.so)
==11482==    by 0x804932F: main (in /home/ary/src/gcmd/src/backend/a.out)
==11482== 
==11482== Conditional jump or move depends on uninitialised value(s)
==11482==    at 0x4077BB9: vfprintf (in /lib/libc-2.6.1.so)
==11482==    by 0x407F9F2: printf (in /lib/libc-2.6.1.so)
==11482==    by 0x804932F: main (in /home/ary/src/gcmd/src/backend/a.out)

и так далее