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Embedded C++, any tips to avoid a local thats only used to return a value on the stack?


By : user3851475
Date : October 16 2020, 11:12 PM
around this issue How complex is SomeDataType? Does it have a lot of members? Does it do a lot of work in a constructor? If so, then I'd avoid this. If not, you may find the compiler will generate good code for this. For example, the compiler will probably do pretty well with integer types.
With a question like this, the answer is almost always: consult the compiler's assembly output.
code :


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How do you usually return an instance of a user-defined type allocated on the local stack


By : Rignesh Tambakuwala
Date : March 29 2020, 07:55 AM
should help you out It greatly depends on the task at hand. I would go for the first approach for functions that create new values while using the second approach for functions that change the parameters. As mentioned by others, in some cases other restrictions (cost of creation / assignment) can affect the decision.
The first definition is clearly stating that it will create a new object out of nothing and will return it. That is, the same definition is stating the semantics of the call.
code :
// snippet 1
//    user code to the different approaches
class X {};
X f1();
void f2( X& );
X f3( X& );
void g( X const & );

void test1()
{
   g( f1() ); // valid code
}
void test2()
{
   X x; // must create instance before
   f2( x ); // then call the function
   g( x );
}
void test3()
{
   X x; // must create instance before
   g( f3( x ) );
}

// snippet 2
class Y {};
class X
{
public:
   X( Y & y ) : y_( y ) {}
private:
   Y & y_;
};
X f1();
void f2( X & );
X f3( X & );

void test1()
{
   X x = f1();
}
void test2or3()
{  
   Y y;
   X x( y ); // user must create with a reference
   f2( x ); // f2 cannot change the reference inside x to another instance
}

// snippet 3
class X
{
private:
   X( X const & );
   X& operator= ( X const & );
};
X f1(); // Returned object cannot be used
void f2( X & );
X f3( X & );

void test1()
{
   X x = f1(); // compilation error
}
void test2()
{
   X x;
   f2( x );
}
void test3()
{
   X x;
   X y = f3( x ); // compilation error
}

How do I avoid changing the Stack Size AND avoid getting a Stack Overflow in C#


By : Swagnificent Snipper
Date : March 29 2020, 07:55 AM
To fix this issue A while back I explored this problem in my blog. Or, rather, I explored a related problem: how do you find the depth of a binary tree without using recursion? A recursive tree depth solution is trivial, but blows the stack if the tree is highly imbalanced.
My recommendation is to study ways of solving this simpler problem, and then decide which of them, if any, could be adapted to your slightly more complex algorithm.

Local varible (stack) returned as function return value


By : John Hall
Date : March 29 2020, 07:55 AM
I hope this helps you . Here is an example for friend functions found on the internet: , Just think of regular types:
code :
int getInt(void) {
    int a = 5:
    return a;
}
g++ -fno-elide-constructors foo.cpp -o foo

Return value optimization of a member of a local stack variable


By : Ali Babaie
Date : March 29 2020, 07:55 AM
it should still fix some issue For RVO to work, the return value needs to be instantiated in the storage where the caller expects to find it. Perhaps this is a register whose name is specified by the calling convention, or perhaps it is on the stack.
std::pair is essentially:
code :
struct foo {
    A first;
    int second;
};

how to avoid routing through local stack in Linux


By : Robert McShirley
Date : March 29 2020, 07:55 AM
it fixes the issue Untested (should work, but I may have missed something):
Linux has several routing tables. Table local contains some routes that the kernel adds automatically for every IP address added to the host. You can see them with ip route show table local. Routes labeled as local indicate local routes that go through the loopback interface. You could delete that route and add a normal unicast route to replace it:
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