Slow LEA instruction

Slow LEA instruction


I am analying a code for Image processing and I find that the bottleneck is slow LEA instructions. can someone help me wth menthods to fix it??



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Ritratto di Peter Wang (Intel)

If LEA instructions with three operands (base, index, offset), there is pressure of using port 1 and port 3 to cause 3 cycles latency - especially in deep loop. I don't think it makes sense to modify (inline?) assembly code directly, recommend to use Intel(r) C/C++ compiler with advanced options, such as O2, xHost, etc.

In source code level, you may review:
1. Reduce index access in loop, if possible
2. Consider data alignment
3. Reduce branch code in loop
4. No dependency between iterations of loop
5. Others I missed

Hello Peter,

Thanks for your response. I will take a look into your recomendations and see how I can optimize my code.

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