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WAIT

The instruction causes the processor to wait until the FPU WAIT state is cleared. The WAIT state is set by the FSAVE and FINIT instructions and cleared by the FWAIT instruction or when the FPU has completed a previous operation.

The following table covers what the source and destinations can be.

DO NOT support LOCK

The WAIT instruction is primarily used in legacy x87 floating-point operations. In x86-64 mode, this instruction is supported for compatibility with 32-bit applications and legacy x87 code.

To avoid synchronization issues or unnecessary CPU stalls, the programmer SHOULD ensure that WAIT is only used when an explicit FWAIT or the completion of an asynchronous FPU operation is required. Failure to properly manage the FPU state can lead to performance degradation or incorrect timing in legacy floating-point calculations.