cmd/compile: intrinsify math.Sqrt by using only the ssa backend

Change-Id: If3cb64f52fe0fd7331b6f1acf3d15dd705dfd633
Reviewed-on: https://go-review.googlesource.com/32591
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

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

@@ -163,7 +163,6 @@ var opnames = []string{
 	ORETJMP:          "RETJMP",
 	OPS:              "PS",
 	OPC:              "PC",
-	OSQRT:            "SQRT",
 	OGETG:            "GETG",
 	OEND:             "END",
 }

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

@@ -187,8 +187,7 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
 		OPLUS,
 		OREAL,
 		OIMAG,
-		OCOM,
-		OSQRT:
+		OCOM:
 		instrumentnode(&n.Left, init, wr, 0)
 		goto ret
 

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

@@ -961,9 +961,6 @@ func (s *state) stmt(n *Node) {
 		p := s.expr(n.Left)
 		s.nilCheck(p)
 
-	case OSQRT:
-		s.expr(n.Left)
-
 	default:
 		s.Fatalf("unhandled stmt %v", n.Op)
 	}
@@ -1213,8 +1210,6 @@ var opToSSA = map[opAndType]ssa.Op{
 	opAndType{OLROT, TUINT16}: ssa.OpLrot16,
 	opAndType{OLROT, TUINT32}: ssa.OpLrot32,
 	opAndType{OLROT, TUINT64}: ssa.OpLrot64,
-
-	opAndType{OSQRT, TFLOAT64}: ssa.OpSqrt,
 }
 
 func (s *state) concreteEtype(t *Type) EType {
@@ -1953,7 +1948,7 @@ func (s *state) expr(n *Node) *ssa.Value {
 				s.newValue1(negop, tp, s.newValue1(ssa.OpComplexImag, tp, a)))
 		}
 		return s.newValue1(s.ssaOp(n.Op, n.Type), a.Type, a)
-	case ONOT, OCOM, OSQRT:
+	case ONOT, OCOM:
 		a := s.expr(n.Left)
 		return s.newValue1(s.ssaOp(n.Op, n.Type), a.Type, a)
 	case OIMAG, OREAL:
@@ -2698,6 +2693,11 @@ func intrinsicInit() {
 			s.vars[&memVar] = s.newValue3(ssa.OpAtomicOr8, ssa.TypeMem, args[0], args[1], s.mem())
 			return nil
 		}, sys.AMD64, sys.ARM64, sys.MIPS),
+
+		/******** math ********/
+		intrinsicKey{"math", "Sqrt"}: enableOnArch(func(s *state, n *Node, args []*ssa.Value) *ssa.Value {
+			return s.newValue1(ssa.OpSqrt, Types[TFLOAT64], args[0])
+		}, sys.AMD64, sys.ARM, sys.ARM64, sys.MIPS, sys.PPC64, sys.S390X),
 	}
 
 	// aliases internal to runtime/internal/atomic

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

@@ -505,7 +505,6 @@ const (
 	ORETJMP // return to other function
 	OPS     // compare parity set (for x86 NaN check)
 	OPC     // compare parity clear (for x86 NaN check)
-	OSQRT   // sqrt(float64), on systems that have hw support
 	OGETG   // runtime.getg() (read g pointer)
 
 	OEND

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

@@ -652,16 +652,6 @@ opswitch:
 		n.Left = walkexpr(n.Left, init)
 		walkexprlist(n.List.Slice(), init)
 
-		if n.Left.Op == ONAME && n.Left.Sym.Name == "Sqrt" &&
-			(n.Left.Sym.Pkg.Path == "math" || n.Left.Sym.Pkg == localpkg && myimportpath == "math") {
-			if Thearch.LinkArch.InFamily(sys.AMD64, sys.ARM, sys.ARM64, sys.MIPS, sys.PPC64, sys.S390X) {
-				n.Op = OSQRT
-				n.Left = n.List.First()
-				n.List.Set(nil)
-				break opswitch
-			}
-		}
-
 		ll := ascompatte(n.Op, n, n.Isddd, t.Params(), n.List.Slice(), 0, init)
 		n.List.Set(reorder1(ll))