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asm
OperandsHere are 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. Side-effects arent allowed in operands of inline asm
, unless < or > constraints are used, because there is no guarantee that the side effects will happen exactly once in an instruction that can update the addressing register.
Simple Constraints: | Basic use of constraints. | |
Multi-Alternative: | When an insn has two alternative constraint-patterns. | |
Modifiers: | More precise control over effects of constraints. | |
Machine Constraints: | Special constraints for some particular machines. |