Chapter 3.9, Problem 3.43PP

Practice Problem 3.43 (solution page 344)

Suppose you are given the job of checking that a C compiler generates the proper code for structure and union access. You write the following structure declaration:

typedef uniun {

struct {

long u;

short v;

char w;

} t1;

struct {

int a [2];

char *p;

} t2;

} u_type;

You write a scries of functions or the form

void get (u_type *up, type *dest) {

*dest = expr;

}

with different access expressions expr and with destination data type type set according to type associated with expr. You then examine tire code generated when compiling the functions to see if they match your expectations.

  Suppose in these functions that up and dest are loaded into registers %rdi and %rsi, respectively. Fill in the following table with data type type and sequences of one to three instructions to compute the expression and store the result at dest.