[dev.cc] cmd/internal/obj: convert liblink C to Go

This CL adds the real cmd/internal/obj packages.
Collectively they correspond to the liblink library.
The conversion was done using rsc.io/c2go's run script
at rsc.io/c2go repo version 706fac7.

This is not the final conversion, just the first working draft.
There will be more updates, but this works well enough
to use with go tool objwriter and pass all.bash.

Change-Id: I9359e835425f995a392bb2fcdbebf29511477bed
Reviewed-on: https://go-review.googlesource.com/3046
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 129 insertions, 0 deletions

diff --git a/src/cmd/internal/obj/pass.go b/src/cmd/internal/obj/pass.go
new file mode 100644
index 0000000000..9918cffada
--- /dev/null
+++ b/src/cmd/internal/obj/pass.go
@@ -0,0 +1,129 @@
+// Inferno utils/6l/pass.c
+// http://code.google.com/p/inferno-os/source/browse/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.
+
+func Brchain(ctxt *Link, p *Prog) *Prog {
+
+	var i int
+
+	for i = 0; i < 20; i++ {
+		if p == nil || int(p.As) != ctxt.Arch.AJMP || p.Pcond == nil {
+			return p
+		}
+		p = p.Pcond
+	}
+
+	return nil
+}
+
+func brloop(ctxt *Link, p *Prog) *Prog {
+	var c int
+	var q *Prog
+
+	c = 0
+	for q = p; q != nil; q = q.Pcond {
+		if int(q.As) != ctxt.Arch.AJMP || q.Pcond == nil {
+			break
+		}
+		c++
+		if c >= 5000 {
+			return nil
+		}
+	}
+
+	return q
+}
+
+func linkpatch(ctxt *Link, sym *LSym) {
+	var c int32
+	var name string
+	var p *Prog
+	var q *Prog
+
+	ctxt.Cursym = sym
+
+	for p = sym.Text; p != nil; p = p.Link {
+		if ctxt.Arch.Progedit != nil {
+			ctxt.Arch.Progedit(ctxt, p)
+		}
+		if int(p.To.Type_) != ctxt.Arch.D_BRANCH {
+			continue
+		}
+		if p.To.U.Branch != nil {
+			// TODO: Remove to.u.branch in favor of p->pcond.
+			p.Pcond = p.To.U.Branch
+
+			continue
+		}
+
+		if p.To.Sym != nil {
+			continue
+		}
+		c = int32(p.To.Offset)
+		for q = sym.Text; q != nil; {
+			if int64(c) == q.Pc {
+				break
+			}
+			if q.Forwd != nil && int64(c) >= 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(c), p, name)
+			p.To.Type_ = int16(ctxt.Arch.D_NONE)
+		}
+
+		p.To.U.Branch = q
+		p.Pcond = q
+	}
+
+	for p = sym.Text; p != nil; p = p.Link {
+		p.Mark = 0 /* initialization for follow */
+		if p.Pcond != nil {
+			p.Pcond = brloop(ctxt, p.Pcond)
+			if p.Pcond != nil {
+				if int(p.To.Type_) == ctxt.Arch.D_BRANCH {
+					p.To.Offset = p.Pcond.Pc
+				}
+			}
+		}
+	}
+}