Eliminating instructions that compute values that are NEVER subsequently used anywhere in the program is called:
Dead code elimination removes assignments to dead variables or unreachable basic blocks, reducing binary size and runtime cost.
Which data-flow analysis is primarily used for Common Subexpression Elimination (CSE)?
Available Expressions analysis identifies expressions already computed along all incoming paths, allowing their re-computation to be replaced with a simple register lookup.
Which data-flow analysis is primarily used for Register Allocation to determine which variables can share the same physical register?
Live Variable Analysis determines overlapping active lifespans of variables; variables whose live ranges do not overlap can share the same physical register.
What is Loop Invariant code?
Loop invariant expressions yield the exact same result on every iteration because their input operands are not modified within the loop.
In reaching-definitions data-flow analysis, what does KILL[B] represent for a basic block B?
For reaching definitions, KILL[B] contains definitions elsewhere in the program that are invalidated by assignments in B. GEN[B] contains definitions generated by B.