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BNDCL

Checks the lower bound of a bound register against the value of a source operand. If the source operand is less than the lower bound, the #BR exception is raised.

The table after the description covers what the source and destinations can be.

DO NOT support LOCK

This instruction is only available in 64-bit mode. It is NOT supported in compatibility mode.

The instruction specifically checks the lower bound stored in the bound register (BND0-BND3) specified by the opcode. Since the bound register is implicit to the opcode, no destination register is modified.

To avoid unexpected #BR exceptions, ensure that the bound register has been properly initialized using BNDMKL or BNDMKU before executing BNDCL. If the bound register contains a value that is not a valid bound, the behavior may result in an immediate exception.