Consider the following pseudo-code.L1: t1 = -1 L2: t2 = 0 L3: t3 = 0 L4: t4 = 4 * t3 L5: t5 = 4 * t2 L6: t6 = t5 * M L7: t7 = t4 + t6 L8: t8 = a[t7] L9: if t8 <= max goto L11 L10: t1 = t8 L11: t3 = t3 + 1 L12: if t3 < M goto L4 L13: t2 = t2 + 1 L14: if t2 < N goto L3 L15: max = t1Which one of the following options CORRECTLY specifies the number of basic blocks and the number of instructions in the largest basic block, respectively ?

To determine the basic blocks, we first identify the leaders using the standard basic block rules:

1. First instruction is a leader:

   • L1

2. Target instructions of any conditional or unconditional jump/goto are leaders:

   • Target of L9 (goto L11)$\rightarrow$L11

   • Target of L12 (goto L4)$\rightarrow$L4

   • Target of L14 (goto L3)$\rightarrow$L3

3. Instructions immediately following any conditional or unconditional jump/goto are leaders:

   • Instruction following L9$\rightarrow$L10

   • Instruction following L12$\rightarrow$L13

   • Instruction following L14$\rightarrow$L15

Thus, the set of leaders is $\{L1, L3, L4, L10, L11, L13, L15\}$.

Now, partitioning the sequence of three-address instructions from each leader up to (but not including) the next leader, we get the following 7 basic blocks:

• Block 1:L1, L2 (2 instructions)

• Block 2:L3 (1 instruction)

• Block 3:L4, L5, L6, L7, L8, L9 (6 instructions)

• Block 4:L10 (1 instruction)

• Block 5:L11, L12 (2 instructions)

• Block 6:L13, L14 (2 instructions)

• Block 7:L15 (1 instruction)

• Total number of basic blocks: $7$

• Largest basic block: Block 3 (L4 to L9) with $6$ instructions.

Hence, the correct option is (D).