This content has not been validated; it was AI-generated following the x86-64 ISA Documentation generation process to maintain high quality. However, as no human has verified this data, errors may exist. If the accuracy of this data is critical, please consult the Intel SDM. The model used to generate this is gemma4:31b

VFPCLASSSS

Classifies a floating-point value by comparing it against a set of predefined categories and stores the resulting classification code into a general-purpose register.

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

DO NOT support LOCK

This instruction is only available when the processor is operating in x86-64 mode or compatibility mode. It requires the SSE3 extension set to be supported by the hardware.

The destination register is overwritten with a u32 classification value. Ensure the destination register is 64-bit to avoid truncation or unexpected behavior in 64-bit environments, although the result itself fits within a dword. Incorrectly interpreting the resulting integer code will lead to logic errors in floating-point exception handling or NaN detection.