DIP56
| Title: | Provide pragma to control function inlining |
|---|---|
| DIP: | 56 |
| Version: | 0 |
| Status: | Draft |
| Created: | 2014-02-23 |
| Last Modified: | 2014-02-23 |
| Author: | Walter Bright |
| Links: |
Contents
Abstract
This proposal uses pragmas to add hints to the compiler.
Rationale
Sometimes generating better code requires runtime profile information. But being a static compiler, not a JIT, the compiler could use such hints from the programmer.
Description
This adds a pragma 'inline' and two values for it: true and false, which influences the inlining of the function they appear in. 'true' means always inline, 'false' means never inline, no argument means default behavior.
If this pragma is outside of a function, it affects the functions in the block it encloses.
Nested pragmas override the outer ones.
If there are multiple pragmas inside a function, the lexically last one that is semantically analyzed controls the behavior.
If the pragma is versioned out or in a false static if conditional, it is ignored.
If a pragma specifies always inline, whether or not the target function(s) are actually inlined is implementation defined, although the implementation will be expected to inline it if practical. Implementations will likely vary in their ability to inline.
These are not attributes because they should not affect the semantics of the function. In particular, the function signature must not be affected.
Usage
pragma(inline, true); // always inline pragma(inline, false); // never inline pragma(inline); // revert to default behavior
Copyright
This document has been placed in the Public Domain.
