What is the main structural advantage of Quadruples over Triples in intermediate code representation?
In Triples, moving an instruction changes its position index, breaking references in other triples. Quadruples explicitly name destination variables, allowing easy instruction movement during optimization.
For the DAG of the expression (a + b) * (a + b), how many unique nodes and operand edges are there if the repeated use of the shared + node is counted as two operand edges?
The unique nodes are a, b, the shared + node, and *, giving 4 nodes. The + node has two operand edges from a and b, and * uses the shared + node twice, giving 4 operand edges when repeated use is counted separately.
In array address calculations for 2D array A[10][20] stored in Row-Major order starting at base address B with element size S, what is the address formula for A[i][j] (0-indexed)?
In row-major order for A[N1][N2], address of A[i][j] = Base + (i * N2 + j) * S. Here N2 = 20, so Address = B + (i * 20 + j) * S.
In Column-Major storage for 2D array A[10][20] with element size S and base address B, what is the address formula for A[i][j] (0-indexed)?
In column-major order for A[N1][N2], address of A[i][j] = Base + (j * N1 + i) * S. Here N1 = 10, so Address = B + (j * 10 + i) * S.
What technique in intermediate code generation for Boolean expressions fills in target labels of jump instructions when their locations become known later?
Backpatching generates jump instructions with blank target labels and maintains lists (truelist, falselist) to fill in target addresses once destination labels are generated.