4 files changed, 15 insertions, 50 deletions

diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go
index d701d545de..5d69fc3868 100644
--- a/src/cmd/compile/internal/walk/convert.go
+++ b/src/cmd/compile/internal/walk/convert.go
@@ -25,9 +25,6 @@ func walkConv(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 		return n.X
 	}
 	if n.Op() == ir.OCONVNOP && ir.ShouldCheckPtr(ir.CurFunc, 1) {
-		if n.Type().IsPtr() && n.X.Type().IsUnsafePtr() { // unsafe.Pointer to *T
-			return walkCheckPtrAlignment(n, init, nil)
-		}
 		if n.Type().IsUnsafePtr() && n.X.Type().IsUintptr() { // uintptr to unsafe.Pointer
 			return walkCheckPtrArithmetic(n, init)
 		}
@@ -414,41 +411,6 @@ func byteindex(n ir.Node) ir.Node {
 	return n
 }
 
-func walkCheckPtrAlignment(n *ir.ConvExpr, init *ir.Nodes, se *ir.SliceExpr) ir.Node {
-	if !n.Type().IsPtr() {
-		base.Fatalf("expected pointer type: %v", n.Type())
-	}
-	elem := n.Type().Elem()
-	var count ir.Node
-	if se != nil {
-		count = se.Max
-	}
-	if count != nil {
-		if !elem.IsArray() {
-			base.Fatalf("expected array type: %v", elem)
-		}
-		elem = elem.Elem()
-	}
-
-	size := elem.Size()
-	if elem.Alignment() == 1 && (size == 0 || size == 1 && count == nil) {
-		return n
-	}
-
-	if count == nil {
-		count = ir.NewInt(1)
-	}
-
-	n.X = cheapExpr(n.X, init)
-	checkPtrCall := mkcall("checkptrAlignment", nil, init, typecheck.ConvNop(n.X, types.Types[types.TUNSAFEPTR]), reflectdata.TypePtr(elem), typecheck.Conv(count, types.Types[types.TUINTPTR]))
-	if se != nil {
-		se.CheckPtrCall = checkPtrCall
-	} else {
-		init.Append(checkPtrCall)
-	}
-	return n
-}
-
 func walkCheckPtrArithmetic(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 	// Calling cheapExpr(n, init) below leads to a recursive call to
 	// walkExpr, which leads us back here again. Use n.Checkptr to
diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go
index ed2d68539d..e5bf6cf0b5 100644
--- a/src/cmd/compile/internal/walk/expr.go
+++ b/src/cmd/compile/internal/walk/expr.go
@@ -807,15 +807,7 @@ func walkSend(n *ir.SendStmt, init *ir.Nodes) ir.Node {
 
 // walkSlice walks an OSLICE, OSLICEARR, OSLICESTR, OSLICE3, or OSLICE3ARR node.
 func walkSlice(n *ir.SliceExpr, init *ir.Nodes) ir.Node {
-
-	checkSlice := ir.ShouldCheckPtr(ir.CurFunc, 1) && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
-	if checkSlice {
-		conv := n.X.(*ir.ConvExpr)
-		conv.X = walkExpr(conv.X, init)
-	} else {
-		n.X = walkExpr(n.X, init)
-	}
-
+	n.X = walkExpr(n.X, init)
 	n.Low = walkExpr(n.Low, init)
 	if n.Low != nil && ir.IsZero(n.Low) {
 		// Reduce x[0:j] to x[:j] and x[0:j:k] to x[:j:k].
@@ -823,9 +815,6 @@ func walkSlice(n *ir.SliceExpr, init *ir.Nodes) ir.Node {
 	}
 	n.High = walkExpr(n.High, init)
 	n.Max = walkExpr(n.Max, init)
-	if checkSlice {
-		n.X = walkCheckPtrAlignment(n.X.(*ir.ConvExpr), init, n)
-	}
 
 	if n.Op().IsSlice3() {
 		if n.Max != nil && n.Max.Op() == ir.OCAP && ir.SameSafeExpr(n.X, n.Max.(*ir.UnaryExpr).X) {
diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index 4de8858f26..7ac1f75c8f 100644
--- a/src/cmd/compile/internal/walk/order.go
+++ b/src/cmd/compile/internal/walk/order.go
@@ -941,6 +941,12 @@ func (o *orderState) stmt(n ir.Node) {
 					if colas {
 						if len(init) > 0 && init[0].Op() == ir.ODCL && init[0].(*ir.Decl).X == n {
 							init = init[1:]
+
+							// iimport may have added a default initialization assignment,
+							// due to how it handles ODCL statements.
+							if len(init) > 0 && init[0].Op() == ir.OAS && init[0].(*ir.AssignStmt).X == n {
+								init = init[1:]
+							}
 						}
 						dcl := typecheck.Stmt(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
 						ncas.PtrInit().Append(dcl)
diff --git a/src/cmd/compile/internal/walk/stmt.go b/src/cmd/compile/internal/walk/stmt.go
index 4581bca3df..f09e916546 100644
--- a/src/cmd/compile/internal/walk/stmt.go
+++ b/src/cmd/compile/internal/walk/stmt.go
@@ -136,6 +136,14 @@ func walkStmt(n ir.Node) ir.Node {
 
 	case ir.OTAILCALL:
 		n := n.(*ir.TailCallStmt)
+
+		var init ir.Nodes
+		n.Call.X = walkExpr(n.Call.X, &init)
+
+		if len(init) > 0 {
+			init.Append(n)
+			return ir.NewBlockStmt(n.Pos(), init)
+		}
 		return n
 
 	case ir.OINLMARK: