+ at the moment in order to keep things simple).
+
+ To illustrate the meaning of USE_LOOP and WRTO_LOOP, consider the following
+ example:
+
+ for (i = 0; i < 100; i++) -- loop 1
+ {
+ for (j = 0; j < 100; j++) -- loop 2
+ {
+ k1 = i;
+ k2 = j;
+
+ use2 (k1, k2);
+
+ for (t = 0; t < 100; t++) -- loop 3
+ use3 (k1, k2);
+
+ }
+ use1 (k1, k2);
+ }
+
+ Both k1 and k2 are invariants in loop3, thus
+ analyze_scalar_evolution_in_loop (loop3, loop3, k1) = k1
+ analyze_scalar_evolution_in_loop (loop3, loop3, k2) = k2
+
+ As they are invariant, it does not matter whether we consider their
+ usage in loop 3 or loop 2, hence
+ analyze_scalar_evolution_in_loop (loop2, loop3, k1) =
+ analyze_scalar_evolution_in_loop (loop2, loop2, k1) = i
+ analyze_scalar_evolution_in_loop (loop2, loop3, k2) =
+ analyze_scalar_evolution_in_loop (loop2, loop2, k2) = [0,+,1]_2
+
+ Similarly for their evolutions with respect to loop 1. The values of K2
+ in the use in loop 2 vary independently on loop 1, thus we cannot express
+ the evolution with respect to loop 1:
+ analyze_scalar_evolution_in_loop (loop1, loop3, k1) =
+ analyze_scalar_evolution_in_loop (loop1, loop2, k1) = [0,+,1]_1
+ analyze_scalar_evolution_in_loop (loop1, loop3, k2) =
+ analyze_scalar_evolution_in_loop (loop1, loop2, k2) = dont_know
+
+ The value of k2 in the use in loop 1 is known, though:
+ analyze_scalar_evolution_in_loop (loop1, loop1, k1) = [0,+,1]_1
+ analyze_scalar_evolution_in_loop (loop1, loop1, k2) = 100
+ */