Editing Inline expansion (section)

{{Short description|Optimization replacing a function call with that function's source code}}
{{Use American English|date=March 2019}}
{{More citations needed|date=December 2013}}

In [[computing]], '''inline expansion''', or '''inlining''', is a manual or [[compiler optimization]] that replaces a function [[call site]] with the body of the called function. Inline expansion is similar to [[macro expansion]], but occurs during compiling, without changing the [[source code]] (the text), while macro expansion occurs before compiling, and results in different text that is then processed by the [[compiler]].

Inlining is an important optimization, but has complex effects on performance.{{sfn|Chen|Chang|Conte|Hwu|1993}} As a [[rule of thumb]], some inlining will improve speed at very minor cost of space, but excess inlining will hurt speed, due to inlined code consuming too much of the [[instruction cache]], and also cost significant space. A survey of the modest academic literature on inlining from the 1980s and 1990s is given in Peyton Jones & Marlow 1999.{{sfn|Peyton Jones|Marlow|1999|loc=8. Related work, p. 17}}