__attribute__((noalias))

Prevents access of data object through an indirect pointer access.

Syntax

  function-parameter __attribute__((noalias));

  variable-declaration __attribute__((noalias));

  variable-definition __attribute__((noalias));

Remarks

This attribute specifies to the compiler that a data object is only accessed directly, helping the optimizer to generate a better code. The sample code in the following listing will not return a correct result if ip is pointed to a.

Listing: Example of the noalias attribute

extern int a __attribute__((noalias));
int f(int *ip)

{

  a = 1;

  *ip = 0;

  return a;   // optimized to return 1;

}