What predefined macro can I use to detect the target architecture in Clang?

Question

I would like to write code depending on whether the target architecture is e.g. armv7, armv7s, or arm64.

The reason that I can't use sysctlbyname is that this would give me the underlying architecture at runtime, but when arm64 e.g. simulates armv7, sysctl (seemingly) still reports arm64.

Answer 1

Although this is not a 100% answer to the question, but may be useful:

When using clang, you can discern between 32 bit arm and 64 bit arm using:

__arm__ which is defined for 32bit arm, and 32bit arm only.

__aarch64__ which is defined for 64bit arm, and 64bit arm only.

Answer 2

clang --target=... -mcpu=... -E - -dM </dev/null will output all the pre-defined preprocessor macros (similar works for gcc, too)

I don't see single macro that provides the answer, but you can probably use some combination of __ARM_ARCH and defined(__ARM_ARCH_*).