Global variables are slower?

[John Wehle]

> Is it correct to summarize that if there are no function calls between
> repeated references to a non-volatile global variable, then it can be
> optimized to work as well as a local variable.

No.  Consider:

int i;
int *p;

int main()
  {
  int a;

  for (i = 0; i < 1000000; i++)
    {
      *p = i + 1;
      a += i;
    }
  }

p might point to i.

-- John
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