Peephole optimization

Peephole optimization is an optimization technique performed on a small set of compiler-generated instructions, known as a peephole or window,^[1]^[2] that involves replacing the instructions with a logically equivalent set that has better performance.

For example:

Instead of pushing a register onto the stack and then immediately popping the value back into the register, remove both instructions
Instead of multiplying x by 2, do x << 1
Instead of multiplying a floating point register by 8, add 3 to the floating point register's exponent

The term peephole optimization was introduced by William Marshall McKeeman in 1965.^[3]

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[McKeeman_1965-3] Cite error: The named reference McKeeman_1965 was invoked but never defined (see the help page).

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