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