image/svg+xml SFENCE—Store Fence Instruction Operand Encoding Description Orders processor execution relative to all memory stores prior to the SFENCE instruction. The processor ensures that every store prior to SFENCE is globally visible before any store after SFENCE becomes globally visible. The SFENCE instruction is ordered with respect to memory stores, other SFENCE instructions, MFENCE instructions, and any serializing instructions (such as the CPUID instruction). It is not ordered with respect to memory loads or the LFENCE instruction. Weakly ordered memory types can be used to achieve higher processor performance through such techniques as out-of-order issue, write-combining, and write-collapsing. The degree to which a consumer of data recognizes or knows that the data is weakly ordered varies among applications and may be unknown to the producer of this data. The SFENCE instruction provides a performance-efficient way of ensuring store ordering between routines that produce weakly-ordered results and routines that consume this data. This instruction’s operation is the same in non-64-bit modes and 64-bit mode. Specification of the instruction's opcode above indicates a ModR/M byte of F8. For this instruction, the processor ignores the r/m field of the ModR/M byte. Thus, SFENCE is encoded by any opcode of the form 0F AE Fx, where x is in the range 8-F. Operation Wait_On_Following_Stores_Until(preceding_stores_globally_visible); Intel C/C ++ Compiler Intrinsic Equivalent void _mm_sfence(void) Exceptions (All Operating Modes) #UD If CPUID.01H:EDX.SSE[bit 25] = 0. If the LOCK prefix is used. Opcode*InstructionOp/ En 64-Bit Mode Compat/ Leg Mode Description NP 0F AE F8SFENCEZOValidValidSerializes store operations. Op/EnOperand 1Operand 2Operand 3Operand 4 ZONANANANA This UNOFFICIAL reference was generated from the official Intel® 64 and IA-32 Architectures Software Developer’s Manual by a dumb script. There is no guarantee that some parts aren't mangled or broken and is distributed WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE .