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I came across this code and need to understand what it is doing. It just seems to be declaring two bytes and then doing nothing…
uint64_t x;
__asm__ __volatile__ (".byte 0x0f, 0x31" : "=A" (x));
Thanks!
This is generating two bytes (0F 31) directly into the code stream. This is an RDTSC instruction, which reads the time-stamp counter into EDX:EAX, which will then be copied to the variable ‘x’ by the output constraint “=A”(x)