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A comment on Memcpy vs. memmove. Parent comment

Re:Memcpy vs. memmove by pkhuong on Monday December 01, 2014 @06:10PM (#8684658)
https://github.com/sbcl/sbcl/blob/master/src/compiler/x86-64... has

0x66 0x0f 0x1f 0x84 0x00 0x00 0x00 0x00 0x00

That's a size override prefix, followed by the dedicated NOP instruction (0x0f 0x1f), and finally 6 bytes to encode an effective address with offset.

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Re:Memcpy vs. memmove by makomk on Monday December 01, 2014 @07:38PM (#8685046)
Multi-byte nops have compatibility issues on some of the more obscure 32-bit x86 CPUs, unfortunately: https://sourceware.org/bugzilla/show_bug.cgi?id=13675
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Re:Memcpy vs. memmove by pkhuong on Monday December 01, 2014 @08:00PM (#8685106)
Right… you have to check cpuid for the long nop feature. I believe 0x66 0x90 is compatible (but slow, I would expect) with older CPUs.
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