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In assembly language programming, the function prologue is a few lines of code at the beginning of a function, which prepare the stack and registers for use within the function. Similarly, the function epilogue appears at the end of the function, and restores the stack and registers to the state they were in before the function was called.
Using the GCC compiler on Linux, the code above must be compiled using the -g flag in order to include appropriate debug information on the binary generated, thus making it possible to inspect it using GDB. Assuming that the file containing the code above is named example.c, the command for the compilation could be: $
GCC is a key component of the GNU toolchain which is used for most projects related to GNU and the Linux kernel. With roughly 15 million lines of code in 2019, GCC is one of the largest free programs in existence. [4] It has played an important role in the growth of free software, as both a tool and an example.
Blocks do not require the use of executable thunks, so they do not share this weakness. On the other hand, blocks introduces a completely new type for the pointer, while pointers to nested functions in GCC are regular function pointers and can be used directly with existing code.
.text.globl _start _start: # _start is the entry point known to the linker xor %ebp, %ebp # effectively RBP := 0, mark the end of stack frames mov (%rsp), %edi # get argc from the stack (implicitly zero-extended to 64-bit) lea 8 (%rsp), %rsi # take the address of argv from the stack lea 16 (%rsp, %rdi, 8), %rdx # take the address of envp from ...
To pass "in memory", the caller allocates memory and passes a pointer to it as a hidden first parameter; the callee populates the memory and returns the pointer, popping the hidden pointer when returning. [2] In Linux, GCC sets the de facto standard for calling conventions. Since GCC version 4.5, the stack must be aligned to a 16-byte boundary ...
Spawn in computing refers to a function that loads and executes a new child process. The current process may wait for the child to terminate or may continue to execute concurrent computing . Creating a new subprocess requires enough memory in which both the child process and the current program can execute.
Dead code is normally considered dead unconditionally. Therefore, it is reasonable attempting to remove dead code through dead-code elimination at compile time. However, in practice it is also common for code sections to represent dead or unreachable code only under certain conditions, which may not be known at the time of compilation or assembly.