How can I determine if a CPU supports the SSE3 instruction set?

Detecting SSE3 Instruction Set Support with CPUID Instructions

The provided code snippet attempts to determine if a CPU supports the SSE3 instruction set using the __cpuid() function. However, using IsProcessorFeaturePresent() is reportedly ineffective on Windows XP.

To effectively check for SSE3 support, we can delve deeper into CPUID instruction utilization:

1. Accessing CPUID Instructions:

   • Windows:

     #define cpuid(info, x)    __cpuidex(info, x, 0)

   • GCC Intrinsics:

     void cpuid(int info[4], int InfoType){
         __cpuid_count(InfoType, 0, info[0], info[1], info[2], info[3]);
     }

2. Feature Detection:

   • Execute the following code:

     int info[4];
     cpuid(info, 0x00000001);
     bool HW_SSE3 = (info[2] &amp; ((int)1 <<  0)) != 0;

   • This checks Bit 0 of the EFLAGS register where a set bit indicates SSE3 support.

It's important to note that this method only detects CPU support for instructions. To execute them, operating system support is also necessary, particularly for:

• x64 Instructions: Requires a 64-bit OS
• AVX (256-bit) Instructions: Requires OS support
• AVX512 (512-bit) Instructions: Requires OS support, detectable with CPUID flag 0xe6

Thus, by employing these techniques, you can effectively determine whether a CPU supports the SSE3 instruction set, ensuring compatibility with your code.

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