__BUILTIN_RETURN_ADDRESS(3) | Library Functions Manual | __BUILTIN_RETURN_ADDRESS(3)

# NAME

`__builtin_return_address` — the return address of a function

# SYNOPSIS

void *
`__builtin_return_address`(unsigned int level);

void *
`__builtin_frame_address`(unsigned int level);

# DESCRIPTION

The `__builtin_return_address`() is a GNU extension for obtaining the return address of the current function or one of the callers of the current function.

The parameter level specifies the number of frames that should be scanned up in the call stack. A value 0 returns the address of the current function, a value 1 requests the address of the caller of the current function, a value 2 asks for the address of the caller's caller, and so forth. If the top of the call stack has been reached, the function will return 0. Note also that on some architectures it is only possible to determine the address of the current function. In such cases a value 0 is returned. Thus, it is usually safe to only use the value 0 for level.

The `__builtin_frame_address`() behaves similarly, but returns the address of the function frame rather than the return address of the function.

# SEE ALSO

gcc(1), __builtin_object_size(3)

# CAVEATS

These are non-standard, compiler-specific extensions.

December 19, 2010 | NetBSD 11.0