force-interlocked-functions.md

title	/forceInterlockedFunctions
description	Learn more about /forceInterlockedFunctions
ms.date	03/07/2025

/forceInterlockedFunctions

Dynamically selects between Armv8.0 load, store exclusive instructions or Armv8.1 Large System Extension (LSE) atomic instructions based on CPU capability at runtime.

Syntax

/forceInterlockedFunctions[-]

Remarks

When possible, this flag avoids using Armv8.0 load and store exclusive instructions, as these instructions can result in livelocks. This flag forces the following interlocked intrinsics to be generated as out-of-line functions:

Operation	8	16	32	64	128	Pointer
Add	None	None	Full	Full	None	None
And	Full	Full	Full	Full	None	None
CompareExchange	Full	Full	Full	Full	Full	Full
Decrement	None	Full	Full	Full	None	None
Exchange	Full	Full	Full	Full	None	Full
ExchangeAdd	Full	Full	Full	Full	None	None
Increment	None	Full	Full	Full	None	None
Or	Full	Full	Full	Full	None	None
Xor	Full	Full	Full	Full	None	None
bittestandreset	None	None	Full	Full	None	None
bittestandset	None	None	Full	Full	None	None

Key:

• Full: supports plain, _acq, _rel, and _nf forms.

• None: Not supported

For more information about interlocked intrinsics, see the "Interlocked intrinsics" section in Arm64 Intrinsics.

To set the /forceInterlockedFunctions compiler option in Visual Studio

1. Open the Property Pages dialog box for the project. For more information, see Set C++ compiler and build properties in Visual Studio.

2. Select the Configuration Properties > C/C++ > Command Line property page.

3. In the Additional options box, add /forceInterlockedFunctions to enable. Choose OK to save your changes.

To set this compiler option programmatically

• See xref:Microsoft.VisualStudio.VCProjectEngine.VCCLCompilerTool.AdditionalOptions%2A.

See also

Arm64 Intrinsics
MSVC compiler options
MSVC compiler command-line syntax