cmd/compile: remove OREGISTER, Node.Reg

OREGISTER is unused.

All remaining uses of Node.Reg use REGSP.

Change-Id: I51cf06826867e576baabd568e04f96d2634f5cad
Reviewed-on: https://go-review.googlesource.com/31856
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -1185,9 +1185,6 @@ func (p *exporter) expr(n *Node) {
 	// case ODDDARG:
 	//	unimplemented - handled by default case
 
-	// case OREGISTER:
-	//	unimplemented - handled by default case
-
 	case OLITERAL:
 		if n.Val().Ctype() == CTNIL && n.Orig != nil && n.Orig != n {
 			p.expr(n.Orig)

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

@@ -837,9 +837,6 @@ func (p *importer) node() *Node {
 	// case ODDDARG:
 	//	unimplemented
 
-	// case OREGISTER:
-	//	unimplemented
-
 	case OLITERAL:
 		typ := p.typ()
 		n := nodlit(p.value(typ))

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

@@ -5,7 +5,6 @@
 package gc
 
 import (
-	"cmd/internal/obj"
 	"fmt"
 	"strconv"
 	"strings"
@@ -1138,9 +1137,6 @@ func (n *Node) exprfmt(s fmt.State, prec int) {
 	case ODDDARG:
 		fmt.Fprint(s, "... argument")
 
-	case OREGISTER:
-		fmt.Fprint(s, obj.Rconv(int(n.Reg)))
-
 	case OLITERAL: // this is a bit of a mess
 		if fmtmode == FErr {
 			if n.Orig != nil && n.Orig != n {
@@ -1511,8 +1507,8 @@ func (n *Node) nodedump(s fmt.State, flag FmtFlag) {
 	default:
 		fmt.Fprintf(s, "%v%j", n.Op, n)
 
-	case OREGISTER, OINDREG:
-		fmt.Fprintf(s, "%v-%v%j", n.Op, obj.Rconv(int(n.Reg)), n)
+	case OINDREGSP:
+		fmt.Fprintf(s, "%v-SP%j", n.Op, n)
 
 	case OLITERAL:
 		fmt.Fprintf(s, "%v-%v%j", n.Op, n.Val(), n)

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

@@ -279,8 +279,7 @@ func nodarg(t interface{}, fp int) *Node {
 		Fatalf("bad fp")
 
 	case 0: // preparing arguments for call
-		n.Op = OINDREG
-		n.Reg = int16(Thearch.REGSP)
+		n.Op = OINDREGSP
 		n.Xoffset += Ctxt.FixedFrameSize()
 
 	case 1: // reading arguments inside call

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

@@ -152,8 +152,7 @@ var opnames = []string{
 	OCHECKNIL:        "CHECKNIL",
 	OVARKILL:         "VARKILL",
 	OVARLIVE:         "VARLIVE",
-	OREGISTER:        "REGISTER",
-	OINDREG:          "INDREG",
+	OINDREGSP:        "INDREGSP",
 	OCMP:             "CMP",
 	ODEC:             "DEC",
 	OINC:             "INC",

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

@@ -403,7 +403,7 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
 		OCHECKNIL,   // always followed by a read.
 		OCLOSUREVAR, // immutable pointer to captured variable
 		ODOTMETH,    // either part of CALLMETH or CALLPART (lowered to PTRLIT)
-		OINDREG,     // at this stage, only n(SP) nodes from nodarg
+		OINDREGSP,   // at this stage, only n(SP) nodes from nodarg
 		ODCL,        // declarations (without value) cannot be races
 		ODCLCONST,
 		ODCLTYPE,

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

@@ -556,7 +556,7 @@ func (s *state) stmt(n *Node) {
 		// Make a fake node to mimic loading return value, ONLY for write barrier test.
 		// This is future-proofing against non-scalar 2-result intrinsics.
 		// Currently we only have scalar ones, which result in no write barrier.
-		fakeret := &Node{Op: OINDREG, Reg: int16(Thearch.REGSP)}
+		fakeret := &Node{Op: OINDREGSP}
 		s.assign(n.List.First(), v1, needwritebarrier(n.List.First(), fakeret), false, n.Lineno, 0, false)
 		s.assign(n.List.Second(), v2, needwritebarrier(n.List.Second(), fakeret), false, n.Lineno, 0, false)
 		return
@@ -1921,11 +1921,7 @@ func (s *state) expr(n *Node) *ssa.Value {
 		// Note we know the volatile result is false because you can't write &f() in Go.
 		return a
 
-	case OINDREG:
-		if int(n.Reg) != Thearch.REGSP {
-			s.Fatalf("OINDREG of non-SP register %s in expr: %v", obj.Rconv(int(n.Reg)), n)
-			return nil
-		}
+	case OINDREGSP:
 		addr := s.entryNewValue1I(ssa.OpOffPtr, ptrto(n.Type), n.Xoffset, s.sp)
 		return s.newValue2(ssa.OpLoad, n.Type, addr, s.mem())
 
@@ -3018,13 +3014,9 @@ func (s *state) addr(n *Node, bounded bool) (*ssa.Value, bool) {
 			s.Fatalf("variable address class %v not implemented", classnames[n.Class])
 			return nil, false
 		}
-	case OINDREG:
-		// indirect off a register
+	case OINDREGSP:
+		// indirect off REGSP
 		// used for storing/loading arguments/returns to/from callees
-		if int(n.Reg) != Thearch.REGSP {
-			s.Fatalf("OINDREG of non-SP register %s in addr: %v", obj.Rconv(int(n.Reg)), n)
-			return nil, false
-		}
 		return s.entryNewValue1I(ssa.OpOffPtr, t, n.Xoffset, s.sp), true
 	case OINDEX:
 		if n.Left.Type.IsSlice() {

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

@@ -1160,7 +1160,7 @@ func ullmancalc(n *Node) {
 	}
 
 	switch n.Op {
-	case OREGISTER, OLITERAL, ONAME:
+	case OLITERAL, ONAME:
 		ul = 1
 		if n.Class == PAUTOHEAP {
 			ul++

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

@@ -35,7 +35,7 @@ type Node struct {
 
 	// Various. Usually an offset into a struct. For example:
 	// - ONAME nodes that refer to local variables use it to identify their stack frame position.
-	// - ODOT, ODOTPTR, and OINDREG use it to indicate offset relative to their base address.
+	// - ODOT, ODOTPTR, and OINDREGSP use it to indicate offset relative to their base address.
 	// - OSTRUCTKEY uses it to store the named field's offset.
 	// - OXCASE and OXFALL use it to validate the use of fallthrough.
 	// Possibly still more uses. If you find any, document them.
@@ -43,9 +43,6 @@ type Node struct {
 
 	Lineno int32
 
-	// OREGISTER, OINDREG
-	Reg int16
-
 	Esc uint16 // EscXXX
 
 	Op        Op
@@ -472,10 +469,7 @@ const (
 	OCHECKNIL   // emit code to ensure pointer/interface not nil
 	OVARKILL    // variable is dead
 	OVARLIVE    // variable is alive
-
-	// thearch-specific registers
-	OREGISTER // a register, such as AX.
-	OINDREG   // offset plus indirect of a register, such as 8(SP).
+	OINDREGSP   // offset plus indirect of REGSP, such as 8(SP).
 
 	// arch-specific opcodes
 	OCMP    // compare: ACMP.

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

@@ -128,8 +128,8 @@ func adjustargs(n *Node, adjust int) {
 			continue
 		}
 
-		if lhs.Op != OINDREG {
-			yyerror("call argument store does not use OINDREG")
+		if lhs.Op != OINDREGSP {
+			yyerror("call argument store does not use OINDREGSP")
 		}
 
 		// can't really check this in machine-indep code.
@@ -512,7 +512,7 @@ opswitch:
 
 	case OTYPE,
 		ONONAME,
-		OINDREG,
+		OINDREGSP,
 		OEMPTY,
 		OGETG:
 
@@ -2166,7 +2166,7 @@ func callnew(t *Type) *Node {
 
 func iscallret(n *Node) bool {
 	n = outervalue(n)
-	return n.Op == OINDREG && n.Reg == int16(Thearch.REGSP)
+	return n.Op == OINDREGSP
 }
 
 func isstack(n *Node) bool {
@@ -2182,8 +2182,8 @@ func isstack(n *Node) bool {
 	}
 
 	switch n.Op {
-	case OINDREG:
-		return n.Reg == int16(Thearch.REGSP)
+	case OINDREGSP:
+		return true
 
 	case ONAME:
 		switch n.Class {