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a4ap Arrays and Pointers
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  1 int main()                           |
  2 {                                    |
  3                                      |main ()
  4                                      |{
  5     int a[256], c, d;                |
  6     int *b;                          |  int * D.2048;
  7                                      |  int D.2049;
  8                                      |  int D.2050;
  9                                      |  int D.2051;
 10                                      |  int D.2052;
 11                                      |  const char * restrict D.2053;
 12                                      |  int a[256];
 13                                      |  int c;
 14                                      |  int d;
 15                                      |  int * b;
 16     b = a;                           |
 17                                      |  b = &a;
 18     *(b + 3) = 20;                   |
 19                                      |  D.2048 = b + 12;
 20                                      |  *D.2048 = 20;
 21     c = a[2];                        |                                        
 22                                      |  c = a[2];                             
 23     a[3] = a[4];                     |                                        
 24                                      |  D.2049 = a[4];                        
 25                                      |  a[3] = D.2049;                        
 26     printf("%d, %d, %d, %d",         |                                        
 27         a[3], *b, c+1, d);           |                                        
 28                                      |  D.2050 = c + 1;                       
 29                                      |  D.2051 = *b;                          
 30                                      |  D.2052 = a[3];                        
 31                                      |  D.2053 = (const char * restrict)      
 32                                      |                &"%d, %d, %d, %d"[0];   
 33                                      |  printf (D.2053, D.2052,               
 34                                      |        D.2051, D.2050, d);             
 35 }                                    |                                        
 36                                      |}                                       

1   "*(b + 3) = 20" is broken down into two steps: 

    (a) The address  of (b  + 3)  is calculated  as (b  + 12)  because 3
        elements in an array of integers occupy 12 bytes.
    (b) The calculated address,  which is stored in  a temporary pointer
        variable is now dereferenced to assign the constant 20.
    
2   The statement  "c = a[2]" can  be represented directly in  GIMPLE as
    there is only one operator (array reference), one result and and two
    operands (a  & 2). However,  the statement  "a[3] = a[4]"  cannot be
    represented in one GIMPLE and hence is broken down using a temporary
    variable.

3   Parameters can only be passed as local variables. Hence the variable
    'd'  is  passed  as  it  is, but  for  the  first  three  parameters
    (array reference, pointer dereference  and arithmetic expression), a
    temporary variable is created to  store the result of the expression
    which is then passed as the parameter.