GATE Computer Science (CS) 2017 Shift 1 Solved Paper

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 for 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 _____.