cmd/8g, cmd/internal/gc: fix GO386=387 build

Adjust Thearch.FREG_MIN/MAX when using non sse2 mode in 8g.

Also, gc.Use_sse is treated as a bool, so make it a bool.

Change-Id: I840411605344bb31c32f492b3e6729166c084f0c
Reviewed-on: https://go-review.googlesource.com/7993Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Run-TryBot: Dave Cheney <dave@cheney.net>

src/cmd/8g/galign.go

@@ -50,8 +50,16 @@ func main() {
 	gc.Thearch.REGRETURN = x86.REG_AX
 	gc.Thearch.REGMIN = x86.REG_AX
 	gc.Thearch.REGMAX = x86.REG_DI
-	gc.Thearch.FREGMIN = x86.REG_X0
-	gc.Thearch.FREGMAX = x86.REG_X7
+	switch v := obj.Getgo386(); v {
+	case "387":
+		gc.Thearch.FREGMIN = x86.REG_F0
+		gc.Thearch.FREGMAX = x86.REG_F7
+	case "sse2":
+		gc.Thearch.FREGMIN = x86.REG_X0
+		gc.Thearch.FREGMAX = x86.REG_X7
+	default:
+		gc.Fatal("unsupported setting GO386=%s", v)
+	}
 	gc.Thearch.MAXWIDTH = MAXWIDTH
 	gc.Thearch.ReservedRegs = resvd
 

src/cmd/8g/ggen.go

@@ -617,7 +617,7 @@ func cgen_float(n *gc.Node, res *gc.Node) {
 		return
 	}
 
-	if gc.Use_sse != 0 {
+	if gc.Use_sse {
 		cgen_floatsse(n, res)
 	} else {
 		cgen_float387(n, res)
@@ -761,7 +761,7 @@ func bgen_float(n *gc.Node, true_ int, likely int, to *obj.Prog) {
 	var et int
 	var n2 gc.Node
 	var ax gc.Node
-	if gc.Use_sse != 0 {
+	if gc.Use_sse {
 		if nl.Addable == 0 {
 			var n1 gc.Node
 			gc.Tempname(&n1, nl.Type)

src/cmd/8g/gsubr.go

@@ -402,7 +402,7 @@ func foptoas(op int, t *gc.Type, flg int) int {
 	a := obj.AXXX
 	et := int(gc.Simtype[t.Etype])
 
-	if gc.Use_sse != 0 {
+	if gc.Use_sse {
 		switch uint32(op)<<16 | uint32(et) {
 		default:
 			gc.Fatal("foptoas-sse: no entry %v-%v", gc.Oconv(int(op), 0), gc.Tconv(t, 0))
@@ -1036,7 +1036,7 @@ func floatmove(f *gc.Node, t *gc.Node) {
 
 	switch uint32(ft)<<16 | uint32(tt) {
 	default:
-		if gc.Use_sse != 0 {
+		if gc.Use_sse {
 			floatmove_sse(f, t)
 		} else {
 			floatmove_387(f, t)

src/cmd/internal/gc/go.go

@@ -632,7 +632,7 @@ var typesw *Node
 
 var nblank *Node
 
-var Use_sse int
+var Use_sse bool // should we generate SSE2 instructions for 386 targets
 
 var hunk string
 

src/cmd/internal/gc/gsubr.go

@@ -692,6 +692,10 @@ Switch:
 		Fatal("out of fixed registers")
 
 	case TFLOAT32, TFLOAT64:
+		if Thearch.Thechar == '8' && !Use_sse {
+			i = Thearch.FREGMIN // x86.REG_F0
+			break Switch
+		}
 		if o != nil && o.Op == OREGISTER {
 			i = int(o.Val.U.Reg)
 			if Thearch.FREGMIN <= i && i <= Thearch.FREGMAX {

src/cmd/internal/gc/lex.go

@@ -278,13 +278,13 @@ func Main() {
 	}
 
 	if Thearch.Thechar == '8' {
-		p := obj.Getgo386()
-		if p == "387" {
-			Use_sse = 0
-		} else if p == "sse2" {
-			Use_sse = 1
-		} else {
-			log.Fatalf("unsupported setting GO386=%s", p)
+		switch v := obj.Getgo386(); v {
+		case "387":
+			Use_sse = false
+		case "sse2":
+			Use_sse = true
+		default:
+			log.Fatalf("unsupported setting GO386=%s", v)
 		}
 	}