[dev.ssa] cmd/compile: handle non-in-place NEG and NOT

This fixes the crypto/subtle tests.

Change-Id: Ie6e721eec3481f67f13de1bfbd7988e227793148
Reviewed-on: https://go-review.googlesource.com/13000Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -2093,9 +2093,18 @@ func genValue(v *ssa.Value) {
 		p.To.Reg = regnum(v.Args[0])
 	case ssa.OpAMD64NEGQ, ssa.OpAMD64NEGL, ssa.OpAMD64NEGW, ssa.OpAMD64NEGB,
 		ssa.OpAMD64NOTQ, ssa.OpAMD64NOTL, ssa.OpAMD64NOTW, ssa.OpAMD64NOTB:
+		x := regnum(v.Args[0])
+		r := regnum(v)
+		if x != r {
+			p := Prog(regMoveAMD64(v.Type.Size()))
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = x
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = r
+		}
 		p := Prog(v.Op.Asm())
 		p.To.Type = obj.TYPE_REG
-		p.To.Reg = regnum(v.Args[0])
+		p.To.Reg = r
 	case ssa.OpSP, ssa.OpSB:
 		// nothing to do
 	case ssa.OpAMD64SETEQ, ssa.OpAMD64SETNE,