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1 comment:

• File src/cpu/x86/cache/cache.c:

  • Patch Set #12, Line 24: CONFIG(X86_CLFLUSH_CAR)

    I'm curious, does the compiler optimize it differently? […]

    I'm not sure if the compiler can infer that cpuid_edx has no side-effect, so it may not be able to optimize out the code as-is.

    In any case, I'd write this function as follows:

     bool clflush_supported(void)
     {
     	/* CLFLUSH while operating in CAR might not be supported by platforms */
     	if (ENV_CACHE_AS_RAM && !CONFIG(X86_CLFLUSH_CAR))
     		return false;
     
     	return !!(cpuid_edx(1) >> CPUID_FEATURE_CLFLUSH_BIT);
     }

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