On 10/11/07, Tomas Svensson <[EMAIL PROTECTED]> wrote: > In the .md-file of my port, I have set an attribute "size" of every > insn, giving its size (obviously), in bytes. Is there any way I can use the > value of this attribute to determine the cost (in e.g. TARGET_RTX_COSTS) > when optimizing for size? Or is there some other smart way of achieving > the same thing? Is it better to use the "length" attribute for this? >
At the time of rtx_costs you have no way of estimating which exact instruction is going to get generated / matched with the backend. So in TARGET_RTX_COSTS you estimate the number of instructions or the size of each instruction. Look at how these are defined in other backends. It is also important that you set up the length attribute correctly so that you can use that for other features like branch shortening and reordering basic blocks. However this is useful in passes in the backend only after RTL insns have finished up with matching with actual insns in the md file. You can set this attribute based on types of the insns if you have these based on the types of instructions probably for scheduling descriptions or manually set this for every define_insn pattern in your backend. HTH cheers Ramana -- Ramana Radhakrishnan
