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Revision 31501a71


Added by Andre Przywara almost 13 years ago

target-i386: implement lzcnt emulation

lzcnt is a AMD Phenom/Barcelona added instruction returning the
number of leading zero bits in a word.
As this is similar to the "bsr" instruction, reuse the existing
code. There need to be some more changes, though, as lzcnt always
returns a valid value (in opposite to bsr, which has a special
case when the operand is 0).
lzcnt is guarded by the ABM CPUID bit (Fn8000_0001:ECX_5).

Signed-off-by: Andre Przywara <>
Signed-off-by: Aurelien Jarno <>


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