Strength reduction in Compiler Design - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to replace multiplication by 2 with a faster operation.

Compiler Design

result = x [1] 1

Drag options to blanks, or click blank then click option'

A*

B+

C<<

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' does not apply strength reduction.

Using '+' or '-' changes the value incorrectly.

Using the left shift operator (<<) by 1 is equivalent to multiplying by 2, which is faster in many processors.

2fill in blank

medium

Complete the code to replace division by 4 with a faster operation.

Compiler Design

result = x [1] 2

Drag options to blanks, or click blank then click option'

A*

B/

C<<

D>>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '/' does not optimize the operation.

Using '<<' multiplies instead of dividing.

Right shifting by 2 bits (>>) divides the number by 4 efficiently.

3fill in blank

hard

Fix the error in the strength reduction code replacing multiplication by 8.

Compiler Design

result = x [1] 3

Drag options to blanks, or click blank then click option'

A<<

B>>

C+

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' does not apply strength reduction.

Using '>>' shifts right, which divides.

Multiplying by 8 is equivalent to left shifting by 3 bits.

4fill in blank

hard

Fill both blanks to replace multiplication and division by powers of two with shifts.

Compiler Design

mul_result = x [1] 2
div_result = y [2] 1

Drag options to blanks, or click blank then click option'

A<<

B>>

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' or '/' does not optimize the operations.

Multiplying by 4 is left shift by 2 bits, dividing by 2 is right shift by 1 bit. Here, the code uses shifts for both operations.

5fill in blank

hard

Fill all three blanks to apply strength reduction for multiplication and division by powers of two.

Compiler Design

a = b [1] 2
c = d [2] 3
e = f [3] 4

Drag options to blanks, or click blank then click option'

A<<

B>>

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '/' for division is slower than shifts.

Using '<<' for division is incorrect.

Multiplying by 2 is left shift by 1 bit, dividing by 8 and 16 uses right shift '>>' by 3 and 4 bits respectively. This shows strength reduction for both multiplication and division.