inlined

Inlined is a term used in programming to describe code that has been expanded at the point where it is used, rather than called as a separate function. Inlining replaces a call to a function with the body of that function, typically during optimization performed by a compiler or a ahead-of-time optimizer. When a function is inlined, the function’s parameters and local variables become part of the call site, and control flow proceeds from there.

The primary benefits of inlining are the elimination of function call overhead and the potential for further optimizations. By seeing the function body in context, the compiler can apply constant folding, dead code elimination, and other analyses across the inlined code, sometimes enabling additional performance gains. Inlining can also improve data locality by reducing jumps and call boundaries.

However, inlining can have drawbacks. It increases code size (code bloat), which can negatively affect instruction cache usage and overall binary size. It can also increase compile times, as the optimizer replicates the function body at multiple sites. Because inlining decisions depend on heuristics, a compiler may inline some calls and not others, even if the programmer requests it.

Language-specific notes vary. In C and C++, the inline keyword is a hint that a function may be inlined and also affects linkage rules in some contexts. In Rust, inlining is controlled with attributes such as #[inline] and #[inline(always)]. In Go, inlining is performed automatically by the compiler, with no explicit keyword. In Java, inlining is primarily a JIT optimization performed at runtime.

Overall, inlining is a common optimization technique that trades code size for speed, with effects that depend on language, compiler, and context.