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/arch (ARM64)

Specifies the Arm A-Profile architecture extension for code generation on ARM64. These switches apply to the ARM64 targeting version of the compiler. For more information about /arch for other target architectures, see /arch (x86), /arch (x64), and /arch (ARM).

Syntax

/arch:<armv8.0|armv8.1|armv8.2|armv8.3|armv8.4|armv8.5|armv8.6|armv8.7|armv8.8|armv8.9>[+feature]
/arch:<armv9.0|armv9.1|armv9.2|armv9.3|armv9.4>[+feature]

Arguments

/arch:armv8.x
Specifies the Armv8-A architecture, where x is a required extension value from 0 to 91. By default, the compiler uses the /arch:armv8.0 behavior if no architecture is specified.

/arch:armv9.x2
Specifies the Armv9-A architecture, where x is a required extension value from 0 to 4. By default, the compiler uses the /arch:armv8.0 behavior if no architecture is specified.

Remarks

You can specify an ARM64 extension from Armv8.0-A through Armv8.9-A, and Armv9.0-A through Armv9.4-A. Optionally, enable one or more architecture features by appending a feature argument to the option3. For example, to target Armv8.0-A and enable feature FEAT_LSE, append feature argument lse so that the option becomes /arch:armv8.0+lse. For more information about available features and their requirements, see /feature (ARM64)3.

Note

Depending on your version of Visual Studio, the compiler may not yet generate instructions from all feature sets required by the extension level you specify. For example, /arch:armv8.1 allows the Interlocked intrinsic functions to use the appropriate atomic instruction introduced with the Armv8.1-A extension feature FEAT_LSE, but compiler support requires Visual Studio 2022 version 17.2 or later.

The _M_ARM64 macro is defined by default when compiling for an ARM64 target. For more information, see Predefined macros.

The __ARM_ARCH macro is defined for /arch:ARMv8.0 and higher. It indicates the ARM architecture extension level that the compiler is targeting. For more information, see Predefined macros.

#if __ARM_ARCH >= 802
    // code that requires ARMv8.2...
#endif

/arch only affects code generation for native functions. When you use /clr to compile, /arch has no effect on code generation for managed functions.

To set the /arch 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 /arch:armv8.0 or replace armv8.0 with a different ARM64 extension. Choose OK to save your changes.

To set this compiler option programmatically

1 Armv8-A architecture extension armv8.9 is available starting in Visual Studio 2022 version 17.10.
2 Armv9-A architecture extensions are available starting in Visual Studio 2022 version 17.10.
3 Architecture feature enablement is available starting in Visual Studio 2022 version 17.10.

See also

/arch (Minimum CPU architecture)
Predefined macros
MSVC compiler options
MSVC compiler command-line syntax

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