How to programmatically check if fused mul add (FMA) instruction are enabled on the CPU?

To programmatically check if the Fused Multiply-Add (FMA) instructions are enabled on the CPU, you can use CPUID instructions to query the CPU capabilities.

In x86 assembly language, you can use the cpuid instruction to retrieve information about the CPU. Specifically, you can check the CPU feature flags to determine if FMA instructions are supported.

Here's an example in NASM syntax:

assemblyCopy code
section .data

    cpuid_features db 0, 0, 0, 0



section .text

    global _start



_start:

    mov eax, 1

    cpuid

    mov [cpuid_features], ecx



    ; Check the FMA feature flag (bit 12 of ECX)

    test ecx, (1 << 12)

    jz fma_not_supported



    ; FMA instructions are supported

    ; Add your code here



    jmp exit



fma_not_supported:

    ; FMA instructions are not supported

    ; Add your code here



exit:

    ; Exit the program

    mov eax, 0x60

    xor edi, edi

    syscall

In this example, the cpuid instruction is used to retrieve the CPU feature information into the ecx register. The FMA feature flag is checked by testing bit 12 of the ecx register. If the flag is set, it means that FMA instructions are supported, and you can execute code that utilizes FMA instructions.

Note that the above example is in assembly language. If you are using a higher-level programming language like C or C++, you can use inline assembly or CPUID utility libraries to perform the CPU feature check.

Keep in mind that the exact implementation may vary depending on the programming language and compiler you are using. It's important to consult the documentation and reference materials for your specific programming environment.