CMPXCHG
SEMAPHORE I486REAL x86_64
CMPXCHG is an instruction of the x86_64 architecture (x86 / x86-64 (covers 16/32/64-bit modes)), category SEMAPHORE. This page lists its 4 encoding forms, distinguished by opcode bytes: B0, B1.
Each form below links to its full decode: the operand roles and where each one is encoded in the instruction, the flag and register effects, and any micro-op sequence authored for it.
XED_CMPXCHG_X86_LEGACY_0F_B0_178054
REG0=GPR8_B():rcw REG1=GPR8_R():r REG2=XED_REG_AL:rcw:SUPP
XED_CMPXCHG_X86_LEGACY_0F_B0_320705
MEM0:rcw:b REG0=GPR8_R():r REG1=XED_REG_AL:rcw:SUPP
XED_CMPXCHG_X86_LEGACY_0F_B1_258234
REG0=GPRv_B():rcw REG1=GPRv_R():r REG2=OrAX():rcw:SUPP
XED_CMPXCHG_X86_LEGACY_0F_B1_971171
MEM0:rcw:v REG0=GPRv_R():r REG1=OrAX():rcw:SUPP