Contents|Index|Previous|Next  Constraints for asm operands   See the following documentation for specific details on what constraint letters you can use with asm operands. Constraints can say whether an operand may be in a register, and which kinds of register; whether the operand can be a memory reference, and which kinds of address; whether the operand may be an immediate constant, and which possible values it may have. Constraints can also require two operands to match. Simple constraints Multiple alternative constraints Constraint modifier characters Constraints for particular machines