In compiler code optimization, what is a Basic Block?
A basic block is a straight-line sequence with one entry point and no internal branch targets. Its terminating instruction may have multiple CFG successors, such as a conditional branch.
In basic block identification rules, which instruction is designated as a 'Leader'?
Leader rules: 1) First instruction, 2) Target of any branch/jump, 3) Instruction immediately following any branch/jump.
Which code optimization replaces an expensive operation (e.g. multiplication x * 2 or i * 4 in a loop) with a cheaper operation (e.g. shift x << 1 or addition addr + 4)?
Strength reduction replaces computationally heavy operations (multiplication, division) with cheaper equivalent operations (addition, shift).
Evaluating constant expressions at COMPILE-TIME (e.g. replacing x = 3 + 5 * 2 with x = 13) is known as:
Constant Folding computes constant arithmetic operations during compilation rather than generating runtime evaluation instructions.
Replacing variable y with constant value 5 in expressions following assignment y = 5 (provided y is not modified) is known as:
Constant Propagation substitutes known constant values for variable references throughout downstream code execution paths.