Debugging, Disassembly & Reversing in Linux for x64 Architecture/

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Disassembly Output in Code Optimization Mode

Disassembly Output in Code Optimization Mode

Learn how to reconstruct a code in C/C++ language with the help of GDB disassembly output in optimization mode.

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Disassembly output with optimization

We can add flags to optimize the code while compiling our source file. The flag -O is used for the optimization of code, and the -O1 flag further optimizes the code size and execution time. There are other flags for optimization, such as -O2 and -O3, which reduce the code size and execution time even further.

Source code

Below is a C/C++ code that will help us reconstruct a program through the GDB disassembly output in optimization mode.

int a, b;
int *pa, *pb;
int main(int argc, char* argv[])
{
	pa = &a;
	pb = &b;
	*pa = 1;
	*pb = 1;
	*pb = *pb + *pa;
	++*pa;
	*pb = *pb * *pa;
	return 0;
}

Compilation and execution of code

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