| // Copyright 2017 The Go Authors. All rights reserved. | |
| // Use of this source code is governed by a BSD-style | |
| // license that can be found in the LICENSE file. | |
| package x86 | |
| // argListMax specifies upper arg count limit expected to be carried by obj.Prog. | |
| // Max len(obj.Prog.RestArgs) can be inferred from this to be 4. | |
| const argListMax int = 6 | |
| type argList [argListMax]uint8 | |
| type ytab struct { | |
| zcase uint8 | |
| zoffset uint8 | |
| // Last arg is usually destination. | |
| // For unary instructions unaryDst is used to determine | |
| // if single argument is a source or destination. | |
| args argList | |
| } | |
| // Returns true if yt is compatible with args. | |
| // | |
| // Elements from args and yt.args are used | |
| // to index ycover table like `ycover[args[i]+yt.args[i]]`. | |
| // This means that args should contain values that already | |
| // multiplied by Ymax. | |
| func (yt *ytab) match(args []int) bool { | |
| // Trailing Yxxx check is required to avoid a case | |
| // where shorter arg list is matched. | |
| // If we had exact yt.args length, it could be `yt.argc != len(args)`. | |
| if len(args) < len(yt.args) && yt.args[len(args)] != Yxxx { | |
| return false | |
| } | |
| for i := range args { | |
| if ycover[args[i]+int(yt.args[i])] == 0 { | |
| return false | |
| } | |
| } | |
| return true | |
| } | |