[LLVMdev] Instruction sets requiring more than 3 operands

[Evan Cheng]

You have to provide more information than that. Let's say your target  
is called FOO, and assuming multiplexid is an i32 immediate. You want  
to define something like this:

def DEMULTIPLEX : I<(ops i32imm:$id, variable_ops),
                                          "demultiplex $id",  
[(FOOMutex imm:$id)]>;

The auto-generated instruction selection function will check that  
operand 0 is a 32-bit immediate and suck up all the other operands  
(if any) trailing it to form a target specific node with 1 or more  
operands. It will evetually be translated into a MachineInstr* with 1  
or more operands.

If the assembly you are generating will actually print out the  
additional operands. You need to define a custom operand with its own  
asm printing method. e.g.

def demux_ops : Operand<i32> {
   let PrintMethod  = "printDemuxOps";
}

Add this method to the target's asm printer class. The method is  
passed a MachineInstr* and OpNum. That allows you to know just  
exactly how many operands there are and etc.

Hope this is enough information.

Evan

On Dec 19, 2006, at 9:59 PM, Seung Jae Lee wrote:

> Dear Mr. Cheng:
>
> Thank you for kind information.
> Can you tell me in more detail about that?
> For example, I am trying to implement 'demultiplex' instruction as  
> follows:
>
> demultiplex <multiplexid,choose,branch0id,branch1id, 
> …,otherwisebranchid>
>
> In this case, the number of branch#id is not definite. It can be 1,  
> 2, 3...or any number.
>
> My question was about this. I am still not sure how to use  
> CALLpcrel32 you mentioned for this.
> Thank you very much.
>
> Seung Jae Lee
>
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