Consider the expression (a – 1) * (((b + c)/ 3) + d)),

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Consider the expression (a – 1) * (((b + c)/ 3) + d)), Let X be the minimum number of registers required by an optimal code generation (without any register spill) algorithm tor a load/store architecture, in which
(i) only load and store instructions can have memory operands and
(ii) arithmetic instructions can have only register or immediate operands.
The value of X is______.

1. 0
2. 1
3. 2
4. 3

Correct Option: C

The given expression is (1) *			b + c		+ d
			3

Let R₁ and R₂ be two registers
Load R₁ ← b
Load R₂ ← c
Add R₁ ← (R₁ + R₂)
Div. R₁ ← R₁ / 3
Load R₂ ← d
Add R₁ ← R₁ + R₂
Load R₂ ← a
Sub. R₂ ← R₂ - 1
Mul. R₁ ← R₁ * R₂
Hence, only two registers are required.