Xcrun also provides information about the XCode environment. $ /Library/Developer/CommandLineTools/usr/bin/python3 -version $ lipo -info \ /Library/Developer/CommandLineTools/usr/bin/python3Īrchitectures in the fat file: /Library/Developer/CommandLineTools/usr/bin/python3 are: x86_64 arm64 For instance, XCode provides python3 as a universal binary, while anaconda may not yet be doing that. Note too, that if the brew (or other installation systems like anaconda ) directories are searched before the XCode ones, you may be running x86_64 versions of tools which are available as universal binaries (so can run natively) in Xcode. That older, x86_64, installation will all continue to work, but you won’t be exploiting your new machine to its full extent. If you copied your existing environment from another, older, MacOS machine, then it will certainly not be pointing at the AArch64 brew environment. This compiler is an aarch64 executable targeting aarch64. This compiler is an x86_64 binary targeting x86_64.Ī version in the AArch64 brew environment installed by default somewhere like /opt/homebrew/Cellar/llvm/11.0.1/bin/. This compiler is a universal-binary which will choose its default target based on the properties of the process from which it was invoked.Ī version in the x86_64 brew environment installed by default somewhere like /usr/local/Cellar/llvm/11.0.0_1/bin/. If we use it to install compilers (for instance if we want more cutting edge LLVM compilers, or support for OpenMP which is not fully enabled in the Apple compilers), then we may have three different versions of the clang command:Ī version in the Apple command line tools installed somewhere like /Library/Developer/CommandLineTools/usr/bin/. This is important once we install other tools with brew. It will therefore see that as the default target environment and likely configure the build it is setting up to use that architecture. Consider cmake, for instance if you are using brew and haven’t installed the AArch64 native version and changed your paths, you’ll be getting the cmake from /usr/local/bin which is an x86_64 image. So… because we used emacs (which is not yet native), we end up with an x86_64 compiler.īut, before you blame emacs, consider that other tools may also not yet be available in AArch64 native form, and that even when they are you need to set up your environment to ensure that you find the right one. And, that version of the compiler defaults to compiling for the x86_64 target. Thus, if our shell is running in x86_64 emulation, when we start the compiler (which is a universal binary, remember), the embedded x86_64 executable will be executed. To make things work more easily for the x86_64 emulated environment, the standard behaviour of MacOS is to maintain the existing process’ architecture at an exec call if possible. In general, a “fat binary” like this could support many more architectures, but the case of interest here is just these two.Īpple utilities, such as the compilers that come with the XCode command line tools, are distributed in this way, so a single executable image found in your $PATH may contain both versions of the tool.Īside from that (which we’ll see below can be confusing!) the environment is the normal, MacOS “Big Sur” one. To allow a single executable image (or runtime library) to run natively on either architecture, the OS (and associated tools) support “universal-binaries” thus a single file can contain both the code required for the AArch64 architecture and also that required for the x86_64 one. That is a good thing since it means we have a useful environment without changing or recompiling any code, but a bad one in terms of potential confusion. The presence of this emulator means that x86_64 native executables can run on this machine without any change. To allow machines built with this processor to run code which was built for the x86_64 architecture, MacOS (in the “Big Sur” and later releases) supplies an x86_64 binary translation emulator (“Rosetta-2”). The Apple M1 is an Apple implementation of an Arm 64-bit ( AArch64 ) architecture processor.
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