which CPUs support MOVBE instruction?

Question

Sometimes GCC generates this instruction when compiling with -march=atom. Does each and every Intel Atom CPU support MOVBE?

What other processors suppo

Answer 1

This instruction was originally unique to the Intel® Atom™ processor.

From Intel side:

The Intel® Compilers 11.0 allow you to target the Intel® Atom™ processor using the /QxSSE3_ATOM or -xSSE3_ATOM compiler options. These options enable the generation of the movbe instruction which is unique to the Intel® Atom™ processor.

In other microarchitectures (http://instlatx64.atw.hu/ with uop info from https://agner.org/optimize/):

• Mainstream Intel: Haswell and later. Including Haswell Xeon (Ex-xxxx v3).
  Decodes as 2 or 3 uops, about the same as bswap + load or store.
• Mainstream AMD: Excavator, and Ryzen-family. Steamroller and earlier don't have it.
  Decodes efficiently to a single uop.

non-mainstream CPUs:

• Legacy in-order Intel Atom: all
• Intel Silvermont-family out-of-order Atom: all. Decodes efficiently to a single uop.

• AMD Jaguar. Decodes efficiently to a single uop.

• Intel Xeon Phi: Knight's Landing (based on Silvermont) and later. (Maybe not on Knight's corner.)