Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures?

by

More Related Contents:

  1. Why is the loop instruction slow? Couldn’t Intel have implemented it efficiently?
  2. Branch alignment for loops involving micro-coded instructions on Intel SnB-family CPUs
  3. 32-byte aligned routine does not fit the uops cache
  4. Size of store buffers on Intel hardware? What exactly is a store buffer?
  5. Which Intel microarchitecture introduced the ADC reg,0 single-uop special case?
  6. What is the best way to set a register to zero in x86 assembly: xor, mov or and?
  7. Enhanced REP MOVSB for memcpy
  8. How many CPU cycles are needed for each assembly instruction?
  9. Adding a redundant assignment speeds up code when compiled without optimization
  10. Is performance reduced when executing loops whose uop count is not a multiple of processor width?
  11. Why is Skylake so much better than Broadwell-E for single-threaded memory throughput?
  12. Why is this SSE code 6 times slower without VZEROUPPER on Skylake?
  13. Understanding the impact of lfence on a loop with two long dependency chains, for increasing lengths
  14. How are x86 uops scheduled, exactly?
  15. Why does breaking the “output dependency” of LZCNT matter?
  16. What is the purpose of the EBP frame pointer register?
  17. What methods can be used to efficiently extend instruction length on modern x86?
  18. What setup does REP do?
  19. Is ADD 1 really faster than INC ? x86 [duplicate]
  20. x86_64: is IMUL faster than 2x SHL + 2x ADD?
  21. Assembly – How to score a CPU instruction by latency and throughput
  22. Unexpectedly poor and weirdly bimodal performance for store loop on Intel Skylake
  23. Why can’t my ultraportable laptop CPU maintain peak performance in HPC
  24. Is it useful to use VZEROUPPER if your program+libraries contain no SSE instructions?
  25. How are cache memories shared in multicore Intel CPUs?
  26. Modern x86 cost model
  27. Return address prediction stack buffer vs stack-stored return address?
  28. Relative performance of x86 inc vs. add instruction
  29. How can the rep stosb instruction execute faster than the equivalent loop?
  30. Do 128bit cross lane operations in AVX512 give better performance?

Leave a Comment