podman

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// Inferno utils/6l/pass.c
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// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/pass.c
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//
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//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
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//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
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//	Portions Copyright © 1997-1999 Vita Nuova Limited
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//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
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//	Portions Copyright © 2004,2006 Bruce Ellis
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//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
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//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
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//	Portions Copyright © 2009 The Go Authors. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package obj
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// Code and data passes.
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// brloop returns the ultimate destination of the series of unconditional jumps beginning at p.
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// In the case of an infinite loop, brloop returns nil.
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func brloop(p *Prog) *Prog {
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	c := 0
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	for q := p; q != nil; q = q.To.Target() {
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		if q.As != AJMP || q.To.Target() == nil {
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			return q
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		}
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		c++
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		if c >= 5000 {
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			// infinite loop
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			return nil
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		}
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	}
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	panic("unreachable")
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}
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// checkaddr checks that a has an expected encoding, especially TYPE_CONST vs TYPE_ADDR.
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func checkaddr(ctxt *Link, p *Prog, a *Addr) {
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	switch a.Type {
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	case TYPE_NONE, TYPE_REGREG2, TYPE_REGLIST:
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		return
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	case TYPE_BRANCH, TYPE_TEXTSIZE:
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		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name != 0 {
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			break
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		}
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		return
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	case TYPE_MEM:
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		return
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	case TYPE_CONST:
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		// TODO(rsc): After fixing SHRQ, check a.Index != 0 too.
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		if a.Name != 0 || a.Sym != nil || a.Reg != 0 {
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			ctxt.Diag("argument is TYPE_CONST, should be TYPE_ADDR, in %v", p)
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			return
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		}
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		if a.Reg != 0 || a.Scale != 0 || a.Name != 0 || a.Sym != nil || a.Val != nil {
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			break
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		}
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		return
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	case TYPE_FCONST, TYPE_SCONST:
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		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name != 0 || a.Offset != 0 || a.Sym != nil {
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			break
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		}
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		return
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	case TYPE_REG:
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		// TODO(rsc): After fixing PINSRQ, check a.Offset != 0 too.
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		// TODO(rsc): After fixing SHRQ, check a.Index != 0 too.
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		if a.Scale != 0 || a.Name != 0 || a.Sym != nil {
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			break
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		}
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		return
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	case TYPE_ADDR:
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		if a.Val != nil {
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			break
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		}
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		if a.Reg == 0 && a.Index == 0 && a.Scale == 0 && a.Name == 0 && a.Sym == nil {
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			ctxt.Diag("argument is TYPE_ADDR, should be TYPE_CONST, in %v", p)
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		}
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		return
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	case TYPE_SHIFT, TYPE_REGREG:
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		if a.Index != 0 || a.Scale != 0 || a.Name != 0 || a.Sym != nil || a.Val != nil {
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			break
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		}
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		return
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	case TYPE_INDIR:
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		// Expect sym and name to be set, nothing else.
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		// Technically more is allowed, but this is only used for *name(SB).
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		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name == 0 || a.Offset != 0 || a.Sym == nil || a.Val != nil {
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			break
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		}
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		return
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	}
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	ctxt.Diag("invalid encoding for argument %v", p)
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}
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func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
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	for p := sym.Func.Text; p != nil; p = p.Link {
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		checkaddr(ctxt, p, &p.From)
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		if p.GetFrom3() != nil {
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			checkaddr(ctxt, p, p.GetFrom3())
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		}
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		checkaddr(ctxt, p, &p.To)
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		if ctxt.Arch.Progedit != nil {
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			ctxt.Arch.Progedit(ctxt, p, newprog)
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		}
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		if p.To.Type != TYPE_BRANCH {
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			continue
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		}
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		if p.To.Val != nil {
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			continue
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		}
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		if p.To.Sym != nil {
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			continue
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		}
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		q := sym.Func.Text
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		for q != nil && p.To.Offset != q.Pc {
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			if q.Forwd != nil && p.To.Offset >= q.Forwd.Pc {
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				q = q.Forwd
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			} else {
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				q = q.Link
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			}
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		}
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		if q == nil {
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			name := "<nil>"
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			if p.To.Sym != nil {
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				name = p.To.Sym.Name
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			}
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			ctxt.Diag("branch out of range (%#x)\n%v [%s]", uint32(p.To.Offset), p, name)
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			p.To.Type = TYPE_NONE
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		}
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		p.To.SetTarget(q)
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	}
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	if !ctxt.Flag_optimize {
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		return
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	}
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	// Collapse series of jumps to jumps.
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	for p := sym.Func.Text; p != nil; p = p.Link {
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		if p.To.Target() == nil {
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			continue
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		}
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		p.To.SetTarget(brloop(p.To.Target()))
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		if p.To.Target() != nil && p.To.Type == TYPE_BRANCH {
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			p.To.Offset = p.To.Target().Pc
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		}
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	}
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}
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