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// 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
}
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