When compiling the following instruction:
movl 4(%ebp), 8(%ebp)
I got: too many memory reference.
What's wrong with it?
The number before the parenthesis is a byte offset (which causes a memory reference to occur), and you cannot have two of them with movl. You need to move the value temporarily to a register first.
movl 4(%ebp), %ecx
movl %ecx, 8(%ebp)
It is not a legal instruction. For most instructions that reference memory you must move it to/from a register.
movl doesn't to memory-memory moves, you have to go by way of a register (thus with two movl instructions).
来源：https://stackoverflow.com/questions/2531682/gas-too-many-memory-reference