Optimization Techniques

Code Motion

• Move invariant computations outside loops to reduce frequency
• Example: a[n*i+j] → ni=n*i; a[ni+j]

Share Common Subexpressions

• Reuse redundant portions of expressions
• Example: (i-1)*n, i*n, (i+1)*n; → int in=i*n; in-n, in in+n;

Reduce Procedure Calls

• Avoid costly function calls in loops when result is invariant
• Example: Move strlen(s) outside loop in int len = strlen(s)

Reduce Memory Accesses

• Minimize memory reads/writes, especially in inner loops
• Example: Accumulate sum in register, write once outside loop

Modern Computing Paradigms

Embedded Systems

• Computers getting smaller and ubiquitous

Internet of Things (IoT)

• Connecting everyday objects to internet
• Applications: smart homes, cities, grids, healthcare, etc.

Big Data and Cloud Computing