Revert "cmd/compile: cleanup nodpc and nodfp"

This reverts commit dcac984b.

Reason for revert: broke LR architectures (arm64, ppc64, s390x)

Change-Id: I531d311c9053e81503c8c78d6cf044b318fc828b
Reviewed-on: https://go-review.googlesource.com/99695
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

src/cmd/compile/internal/gc/builtin/runtime.go

@@ -22,7 +22,7 @@ func throwinit()
 func panicwrap()
 
 func gopanic(interface{})
-func gorecover(uintptr) interface{}
+func gorecover(*int32) interface{}
 func goschedguarded()
 
 func printbool(bool)

src/cmd/compile/internal/gc/esc.go

@@ -2025,6 +2025,10 @@ func addrescapes(n *Node) {
 		// Nothing to do.
 
 	case ONAME:
+		if n == nodfp {
+			break
+		}
+
 		// if this is a tmpname (PAUTO), it was tagged by tmpname as not escaping.
 		// on PPARAM it means something different.
 		if n.Class() == PAUTO && n.Esc == EscNever {

src/cmd/compile/internal/gc/go.go

@@ -232,6 +232,8 @@ var writearchive bool
 
 var Nacl bool
 
+var nodfp *Node
+
 var disable_checknil int
 
 var autogeneratedPos src.XPos

src/cmd/compile/internal/gc/pgen.go

@@ -131,7 +131,12 @@ func (s *ssafn) AllocFrame(f *ssa.Func) {
 		for _, v := range b.Values {
 			if n, ok := v.Aux.(*Node); ok {
 				switch n.Class() {
-				case PAUTO, PPARAM, PPARAMOUT:
+				case PPARAM, PPARAMOUT:
+					// Don't modify nodfp; it is a global.
+					if n != nodfp {
+						n.Name.SetUsed(true)
+					}
+				case PAUTO:
 					n.Name.SetUsed(true)
 				}
 			}

src/cmd/compile/internal/gc/racewalk.go

@@ -64,11 +64,21 @@ func instrument(fn *Node) {
 	}
 
 	if flag_race {
-		lno := lineno
+		// nodpc is the PC of the caller as extracted by
+		// getcallerpc. We use -widthptr(FP) for x86.
+		// BUG: this will not work on arm.
+		nodpc := *nodfp
+		nodpc.Type = types.Types[TUINTPTR]
+		nodpc.Xoffset = int64(-Widthptr)
+		savedLineno := lineno
 		lineno = src.NoXPos
-		fn.Func.Enter.Prepend(mkcall("racefuncenter", nil, nil, callerPC))
-		fn.Func.Exit.Append(mkcall("racefuncexit", nil, nil))
-		lineno = lno
+		nd := mkcall("racefuncenter", nil, nil, &nodpc)
+
+		fn.Func.Enter.Prepend(nd)
+		nd = mkcall("racefuncexit", nil, nil)
+		fn.Func.Exit.Append(nd)
+		fn.Func.Dcl = append(fn.Func.Dcl, &nodpc)
+		lineno = savedLineno
 	}
 
 	if Debug['W'] != 0 {

src/cmd/compile/internal/gc/ssa.go

@@ -1471,12 +1471,6 @@ func (s *state) expr(n *Node) *ssa.Value {
 			sym := funcsym(n.Sym).Linksym()
 			return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type), sym, s.sb)
 		}
-		switch n {
-		case callerSP:
-			return s.newValue0(ssa.OpGetCallerSP, n.Type)
-		case callerPC:
-			return s.newValue0(ssa.OpGetCallerPC, n.Type)
-		}
 		if s.canSSA(n) {
 			return s.variable(n, n.Type)
 		}
@@ -3474,6 +3468,10 @@ func (s *state) addr(n *Node, bounded bool) *ssa.Value {
 			if v != nil {
 				return v
 			}
+			if n == nodfp {
+				// Special arg that points to the frame pointer (Used by ORECOVER).
+				return s.entryNewValue1A(ssa.OpAddr, t, n, s.sp)
+			}
 			s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
 			return nil
 		case PAUTO:

src/cmd/compile/internal/gc/universe.go

@@ -466,19 +466,8 @@ func finishUniverse() {
 		s1.Block = s.Block
 	}
 
-	callerSP = newname(lookup(".sp"))
-	callerSP.Type = types.Types[TUINTPTR]
-	callerSP.SetClass(PPARAM)
-	callerSP.Name.SetUsed(true)
-
-	callerPC = newname(lookup(".pc"))
-	callerPC.Type = types.Types[TUINTPTR]
-	callerPC.SetClass(PPARAM)
-	callerPC.Name.SetUsed(true)
+	nodfp = newname(lookup(".fp"))
+	nodfp.Type = types.Types[TINT32]
+	nodfp.SetClass(PPARAM)
+	nodfp.Name.SetUsed(true)
 }
-
-var (
-	// Pseudo variables that represent the caller's SP and PC, respectively.
-	callerSP *Node
-	callerPC *Node
-)

src/cmd/compile/internal/gc/walk.go

@@ -604,7 +604,7 @@ opswitch:
 		n = mkcall("gopanic", nil, init, n.Left)
 
 	case ORECOVER:
-		n = mkcall("gorecover", n.Type, init, callerSP)
+		n = mkcall("gorecover", n.Type, init, nod(OADDR, nodfp, nil))
 
 	case OCLOSUREVAR, OCFUNC:
 		n.SetAddable(true)