 RealView Compiler User's Guide | |
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RealView Compiler User's Guide
Preface Introduction Getting started with the ARM Compiler Compiler Features Coding Practices Optimizing code
Optimizing for size versus speed Optimization levels and the debug view Selecting the target device Optimizing loops Using volatile Code metrics Measuring code and data sizes Measuring stack use Reducing debug information in objects and librarie Functions Minimizing parameter passing overhead __value_in_regs __pure Placing ARM function qualifiers Inlining How the compiler decides to inline When is it practical for the compiler to inline? Managing inlining Inlining functions across multiple files Debugging data and the --[no]_inline keyword Marking functions as static Setting breakpoints on inlined functions in ROM im Aligning data About data alignment The __packed qualifier and unaligned accesses to d __packed structures versus individually __packed f Using floating-point arithmetic Support for floating-point operations VFP architectures The --fpu option Floating-point linkage The --fpmode option Using the --fpu option VFP support Trapping and identifying division-by-zero errors Integer division (Software) Floating point division Support for ARM architecture v6 Instruction generation Alignment support Endian support Diagnostic Messages Using the Inline and Embedded Assemblers SemihostingHow the compiler decides to inline
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| Home > Coding Practices > Inlining > How the compiler decides to inline | |||
When inlining is enabled, the compiler uses a complex decision tree to decide when a function is inlined. The compiler uses the following simplified algorithm to determine if a function is to be inlined:
If the function is qualified with
__forceinline, then the function is inlined if it is possible to do so.If the function is qualified with
__inlineand the option--forceinlineis selected, then the function is inlined if it is possible to do so.If the function is qualified with
__inlineand the option--forceinlineis not selected, then the function is inlined if it is sensible to do so.If the optimization level is
-O2or higher, or--autoinlineis selected, then the function is inlined if it is sensible to inline the function, and it is possible to do so.
When deciding if it is practical to inline a function, the compiler takes into account several other criteria, including whether you select ‑Ospace or ‑Otime. Select ‑Otime to increase the likelihood that a function is inlined. See When is it practical for the compiler to inline? for more information.
You cannot override any decision made by the compiler about when it is practical to inline a function. For example, you cannot force a function to be inlined if the compiler thinks it is not sensible.
| Copyright © 2007 ARM Limited. All rights reserved. | ARM DUI 0375A |
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