CO & architecture closed

Question

The arithmetic expression $: (a + b) \ast c - d / e \ast \ast f$ is to be evaluated on a two-address machine, where each operands, the number of registers required to evaluate this expression is ______. The number of memory access of operand is __________.

Answer 1

 (a + b) * c - d / e * * f 

R1=a.  for a R1 memory is referred for the first time here

R2=b.   for a R2 memory is referred for the first time here

R1=R1+R2         they are added and stored in R1 for that memory is referred.

R2=c

R1=R1*R2

R2=f

R3=e.     for a R3 memory is referred for the first time here

R3=R3**R2.      they are added and stored in R3 for that memory is referred.

R1=R1/R3.         they are added and stored in R1 for that memory is referred.

So total 3 registers are required.

No of memory access of operands is how many times memory is referred.

Which is 6 as highlighted entries.

Answer 2

** is used for exponentiation.
So, in total 3 registers are required and 6 memory operations in total to fetch all operands.

Comments

Can you please explain in more detail.

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@Satbir https://gateoverflow.in/26428/gate1991-01-xi?show=40794#c40794