millfork/docs/abi/inlining.md

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Macros and inlining

Macros

macro keyword

Automatic inlining

You can control inlining behavior in several ways:

• functions declared with the inline keyword will be inlined if possible

• functions declared with the noinline keyword will never be inlined

• the remaining functions may be inlined only if the -finline command-line option is enabled and the compiler decides the function is worth doing

Automatic subroutine extraction

Subroutine extraction is the opposite of inlining.

When given the -fsubroutine-extraction, the compiler will attempt to extract common code fragments to new subroutines. The code will get smaller and slower.

Generally, when using -fsubroutine-extraction, it's recommended to also use -finline. This allows the compiler to first inline and optimize code and then extract it back when appropriate.