cmd/compile: fix import/export of Init and Def fields.

Change so that the Init and Def fields of assignments and OSELREVC2
nodes are exported/imported properly.

A quirk of iimport.go is that it automatically converts an ODCL node to
an ODCL/OAS sequence (where the OAS is to just zero out the declared
variable). Given that the Inits are properly fixed, o.stmt needs
adjustment for the OSELRECV2 case to skip over the new OAS nodes that
are inserted only on re-import.

Change-Id: Ic38017efca4b7ca9b3952ffbbfca067380902b7a
Reviewed-on: https://go-review.googlesource.com/c/go/+/350809
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>

diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index f001017a867b273b21564e509e88abf710847053..a9522c38875221a04d0039fc47fc705bc3da4b7b 100644 (file)
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -1456,10 +1456,23 @@ func (w *exportWriter) node(n ir.Node) {
        }
 }
 
-// Caution: stmt will emit more than one node for statement nodes n that have a non-empty
-// n.Ninit and where n cannot have a natural init section (such as in "if", "for", etc.).
+func isNonEmptyAssign(n ir.Node) bool {
+       switch n.Op() {
+       case ir.OAS:
+               if n.(*ir.AssignStmt).Y != nil {
+                       return true
+               }
+       case ir.OAS2, ir.OAS2DOTTYPE, ir.OAS2FUNC, ir.OAS2MAPR, ir.OAS2RECV:
+               return true
+       }
+       return false
+}
+
+// Caution: stmt will emit more than one node for statement nodes n that have a
+// non-empty n.Ninit and where n is not a non-empty assignment or a node with a natural init
+// section (such as in "if", "for", etc.).
 func (w *exportWriter) stmt(n ir.Node) {
-       if len(n.Init()) > 0 && !ir.StmtWithInit(n.Op()) {
+       if len(n.Init()) > 0 && !ir.StmtWithInit(n.Op()) && !isNonEmptyAssign(n) {
                // can't use stmtList here since we don't want the final OEND
                for _, n := range n.Init() {
                        w.stmt(n)
@@ -1495,8 +1508,10 @@ func (w *exportWriter) stmt(n ir.Node) {
                if n.Y != nil {
                        w.op(ir.OAS)
                        w.pos(n.Pos())
+                       w.stmtList(n.Init())
                        w.expr(n.X)
                        w.expr(n.Y)
+                       w.bool(n.Def)
                }
 
        case ir.OASOP:
@@ -1517,8 +1532,10 @@ func (w *exportWriter) stmt(n ir.Node) {
                        w.op(ir.OAS2)
                }
                w.pos(n.Pos())
+               w.stmtList(n.Init())
                w.exprList(n.Lhs)
                w.exprList(n.Rhs)
+               w.bool(n.Def)
 
        case ir.ORETURN:
                n := n.(*ir.ReturnStmt)
@@ -2065,8 +2082,10 @@ func (w *exportWriter) expr(n ir.Node) {
                n := n.(*ir.AssignListStmt)
                w.op(ir.OSELRECV2)
                w.pos(n.Pos())
+               w.stmtList(n.Init())
                w.exprList(n.Lhs)
                w.exprList(n.Rhs)
+               w.bool(n.Def)
 
        default:
                base.Fatalf("cannot export %v (%d) node\n"+

diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index b3a0eb8871ab427fbf0febef5952983cc78c0902..3b3c2a2e2abd8517947d3918a3be129642ffee71 100644 (file)
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -1619,7 +1619,12 @@ func (r *importReader) node() ir.Node {
        //      unreachable - never exported
 
        case ir.OAS:
-               return ir.NewAssignStmt(r.pos(), r.expr(), r.expr())
+               pos := r.pos()
+               init := r.stmtList()
+               n := ir.NewAssignStmt(pos, r.expr(), r.expr())
+               n.SetInit(init)
+               n.Def = r.bool()
+               return n
 
        case ir.OASOP:
                n := ir.NewAssignOpStmt(r.pos(), r.op(), r.expr(), nil)
@@ -1636,7 +1641,12 @@ func (r *importReader) node() ir.Node {
                        // unreachable - mapped to case OAS2 by exporter
                        goto error
                }
-               return ir.NewAssignListStmt(r.pos(), op, r.exprList(), r.exprList())
+               pos := r.pos()
+               init := r.stmtList()
+               n := ir.NewAssignListStmt(pos, op, r.exprList(), r.exprList())
+               n.SetInit(init)
+               n.Def = r.bool()
+               return n
 
        case ir.ORETURN:
                return ir.NewReturnStmt(r.pos(), r.exprList())
@@ -1721,7 +1731,12 @@ func (r *importReader) node() ir.Node {
                return n
 
        case ir.OSELRECV2:
-               return ir.NewAssignListStmt(r.pos(), ir.OSELRECV2, r.exprList(), r.exprList())
+               pos := r.pos()
+               init := r.stmtList()
+               n := ir.NewAssignListStmt(pos, ir.OSELRECV2, r.exprList(), r.exprList())
+               n.SetInit(init)
+               n.Def = r.bool()
+               return n
 
        default:
                base.Fatalf("cannot import %v (%d) node\n"+

diff --git a/src/cmd/compile/internal/walk/order.go b/src/cmd/compile/internal/walk/order.go
index 4de8858f2636ad91c821bff3b9943989128b8970..7ac1f75c8f21148edad1f060d7f49a14cd888344 100644 (file)
--- 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)