1 files changed, 181 insertions, 0 deletions
diff --git a/src/cmd/internal/obj/pass.go b/src/cmd/internal/obj/pass.go
new file mode 100644
index 0000000..066b779
--- /dev/null
+++ b/src/cmd/internal/obj/pass.go
@@ -0,0 +1,181 @@
+// Inferno utils/6l/pass.c
+// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/pass.c
+//
+//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
+//	Portions Copyright © 1997-1999 Vita Nuova Limited
+//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
+//	Portions Copyright © 2004,2006 Bruce Ellis
+//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
+//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
+//	Portions Copyright © 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package obj
+
+// Code and data passes.
+
+// brloop returns the ultimate destination of the series of unconditional jumps beginning at p.
+// In the case of an infinite loop, brloop returns nil.
+func brloop(p *Prog) *Prog {
+	c := 0
+	for q := p; q != nil; q = q.To.Target() {
+		if q.As != AJMP || q.To.Target() == nil {
+			return q
+		}
+		c++
+		if c >= 5000 {
+			// infinite loop
+			return nil
+		}
+	}
+	panic("unreachable")
+}
+
+// checkaddr checks that a has an expected encoding, especially TYPE_CONST vs TYPE_ADDR.
+func checkaddr(ctxt *Link, p *Prog, a *Addr) {
+	switch a.Type {
+	case TYPE_NONE, TYPE_REGREG2, TYPE_REGLIST:
+		return
+
+	case TYPE_BRANCH, TYPE_TEXTSIZE:
+		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name != 0 {
+			break
+		}
+		return
+
+	case TYPE_MEM:
+		return
+
+	case TYPE_CONST:
+		// TODO(rsc): After fixing SHRQ, check a.Index != 0 too.
+		if a.Name != 0 || a.Sym != nil || a.Reg != 0 {
+			ctxt.Diag("argument is TYPE_CONST, should be TYPE_ADDR, in %v", p)
+			return
+		}
+
+		if a.Reg != 0 || a.Scale != 0 || a.Name != 0 || a.Sym != nil || a.Val != nil {
+			break
+		}
+		return
+
+	case TYPE_FCONST, TYPE_SCONST:
+		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name != 0 || a.Offset != 0 || a.Sym != nil {
+			break
+		}
+		return
+
+	case TYPE_REG:
+		// TODO(rsc): After fixing PINSRQ, check a.Offset != 0 too.
+		// TODO(rsc): After fixing SHRQ, check a.Index != 0 too.
+		if a.Scale != 0 || a.Name != 0 || a.Sym != nil {
+			break
+		}
+		return
+
+	case TYPE_ADDR:
+		if a.Val != nil {
+			break
+		}
+		if a.Reg == 0 && a.Index == 0 && a.Scale == 0 && a.Name == 0 && a.Sym == nil {
+			ctxt.Diag("argument is TYPE_ADDR, should be TYPE_CONST, in %v", p)
+		}
+		return
+
+	case TYPE_SHIFT, TYPE_REGREG:
+		if a.Index != 0 || a.Scale != 0 || a.Name != 0 || a.Sym != nil || a.Val != nil {
+			break
+		}
+		return
+
+	case TYPE_INDIR:
+		// Expect sym and name to be set, nothing else.
+		// Technically more is allowed, but this is only used for *name(SB).
+		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name == 0 || a.Offset != 0 || a.Sym == nil || a.Val != nil {
+			break
+		}
+		return
+	case TYPE_SPECIAL:
+		if a.Reg != 0 || a.Index != 0 || a.Scale != 0 || a.Name != 0 || a.Class != 0 || a.Sym != nil {
+			break
+		}
+		return
+	}
+
+	ctxt.Diag("invalid encoding for argument %v", p)
+}
+
+func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
+	for p := sym.Func().Text; p != nil; p = p.Link {
+		checkaddr(ctxt, p, &p.From)
+		for _, v := range p.RestArgs {
+			checkaddr(ctxt, p, &v.Addr)
+		}
+		checkaddr(ctxt, p, &p.To)
+
+		if ctxt.Arch.Progedit != nil {
+			ctxt.Arch.Progedit(ctxt, p, newprog)
+		}
+		if p.To.Type != TYPE_BRANCH {
+			continue
+		}
+		if p.To.Val != nil {
+			continue
+		}
+
+		if p.To.Sym != nil {
+			continue
+		}
+		q := sym.Func().Text
+		for q != nil && p.To.Offset != q.Pc {
+			if q.Forwd != nil && p.To.Offset >= q.Forwd.Pc {
+				q = q.Forwd
+			} else {
+				q = q.Link
+			}
+		}
+
+		if q == nil {
+			name := "<nil>"
+			if p.To.Sym != nil {
+				name = p.To.Sym.Name
+			}
+			ctxt.Diag("branch out of range (%#x)\n%v [%s]", uint32(p.To.Offset), p, name)
+			p.To.Type = TYPE_NONE
+		}
+
+		p.To.SetTarget(q)
+	}
+
+	if !ctxt.Flag_optimize {
+		return
+	}
+
+	// Collapse series of jumps to jumps.
+	for p := sym.Func().Text; p != nil; p = p.Link {
+		if p.To.Target() == nil {
+			continue
+		}
+		p.To.SetTarget(brloop(p.To.Target()))
+		if p.To.Target() != nil && p.To.Type == TYPE_BRANCH {
+			p.To.Offset = p.To.Target().Pc
+		}
+	}
+}