How can I determine the CPU architecture for which my C/C code is being compiled?

Compiling for a Specific CPU Architecture

When writing C or C code, it's often necessary to know the target CPU architecture for which you are compiling. This information can be useful for optimizing code performance or ensuring compatibility with specific hardware. Different compilers utilize various non-standard preprocessor definitions to distinguish CPU architectures (e.g., _M_X86 in MSVS, i386__, and __arm in GCC).

Standard Detection Methods

Unfortunately, there is no universal standard for detecting CPU architecture at compile time. However, the following external function can detect the architecture for a wide range of compilers:

extern "C" {
    const char *getBuild() { 
        #if defined(__x86_64__) || defined(_M_X64)
        return "x86_64";
        #elif defined(i386) || defined(__i386__) || defined(__i386) || defined(_M_IX86)
        return "x86_32";
        #elif defined(__ARM_ARCH_2__)
        return "ARM2";
        #elif defined(__ARM_ARCH_3__) || defined(__ARM_ARCH_3M__)
        return "ARM3";
        #elif defined(__ARM_ARCH_4T__) || defined(__TARGET_ARM_4T)
        return "ARM4T";
        #elif defined(__ARM_ARCH_5_) || defined(__ARM_ARCH_5E_)
        return "ARM5"
        #elif defined(__ARM_ARCH_6T2_) || defined(__ARM_ARCH_6T2_)
        return "ARM6T2";
        #elif defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__)
        return "ARM6";
        #elif defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__)
        return "ARM7";
        #elif defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__)
        return "ARM7A";
        #elif defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__)
        return "ARM7R";
        #elif defined(__ARM_ARCH_7M__)
        return "ARM7M";
        #elif defined(__ARM_ARCH_7S__)
        return "ARM7S";
        #elif defined(__aarch64__) || defined(_M_ARM64)
        return "ARM64";
        #elif defined(mips) || defined(__mips__) || defined(__mips)
        return "MIPS";
        #elif defined(__sh__)
        return "SUPERH";
        #elif defined(__powerpc) || defined(__powerpc__) || defined(__powerpc64__) || defined(__POWERPC__) || defined(__ppc__) || defined(__PPC__) || defined(_ARCH_PPC)
        return "POWERPC";
        #elif defined(__PPC64__) || defined(__ppc64__) || defined(_ARCH_PPC64)
        return "POWERPC64";
        #elif defined(__sparc__) || defined(__sparc)
        return "SPARC";
        #elif defined(__m68k__)
        return "M68K";
        #else
        return "UNKNOWN";
        #endif
    }
}

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