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cmd/compile: fix constant index bounds check and error message
While here, rename nonnegintconst to indexconst (because that's what it is) and add Fatalf calls where we are not expecting the indexconst call to fail, and fixed wrong comparison in smallintconst. Fixes #23781. Change-Id: I86eb13081c450943b1806dfe3ae368872f76639a Reviewed-on: https://go-review.googlesource.com/c/151599 Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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@ -1229,6 +1229,7 @@ func strlit(n *Node) string {
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return n.Val().U.(string)
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}
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// TODO(gri) smallintconst is only used in one place - can we used indexconst?
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func smallintconst(n *Node) bool {
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if n.Op == OLITERAL && Isconst(n, CTINT) && n.Type != nil {
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switch simtype[n.Type.Etype] {
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@ -1243,7 +1244,7 @@ func smallintconst(n *Node) bool {
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case TIDEAL, TINT64, TUINT64, TPTR:
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v, ok := n.Val().U.(*Mpint)
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if ok && v.Cmp(minintval[TINT32]) > 0 && v.Cmp(maxintval[TINT32]) < 0 {
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if ok && v.Cmp(minintval[TINT32]) >= 0 && v.Cmp(maxintval[TINT32]) <= 0 {
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return true
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}
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}
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@ -1252,21 +1253,24 @@ func smallintconst(n *Node) bool {
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return false
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}
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// nonnegintconst checks if Node n contains a constant expression
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// representable as a non-negative small integer, and returns its
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// (integer) value if that's the case. Otherwise, it returns -1.
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func nonnegintconst(n *Node) int64 {
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// indexconst checks if Node n contains a constant expression
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// representable as a non-negative int and returns its value.
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// If n is not a constant expression, not representable as an
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// integer, or negative, it returns -1. If n is too large, it
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// returns -2.
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func indexconst(n *Node) int64 {
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if n.Op != OLITERAL {
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return -1
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}
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// toint will leave n.Val unchanged if it's not castable to an
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// Mpint, so we still have to guard the conversion.
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v := toint(n.Val())
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v := toint(n.Val()) // toint returns argument unchanged if not representable as an *Mpint
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vi, ok := v.U.(*Mpint)
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if !ok || vi.CmpInt64(0) < 0 || vi.Cmp(maxintval[TINT32]) > 0 {
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if !ok || vi.CmpInt64(0) < 0 {
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return -1
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}
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if vi.Cmp(maxintval[TINT]) > 0 {
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return -2
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}
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return vi.Int64()
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}
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@ -711,7 +711,10 @@ func fixedlit(ctxt initContext, kind initKind, n *Node, var_ *Node, init *Nodes)
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var k int64
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splitnode = func(r *Node) (*Node, *Node) {
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if r.Op == OKEY {
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k = nonnegintconst(r.Left)
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k = indexconst(r.Left)
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if k < 0 {
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Fatalf("fixedlit: invalid index %v", r.Left)
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}
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r = r.Right
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}
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a := nod(OINDEX, var_, nodintconst(k))
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@ -893,7 +896,10 @@ func slicelit(ctxt initContext, n *Node, var_ *Node, init *Nodes) {
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var index int64
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for _, value := range n.List.Slice() {
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if value.Op == OKEY {
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index = nonnegintconst(value.Left)
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index = indexconst(value.Left)
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if index < 0 {
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Fatalf("slicelit: invalid index %v", value.Left)
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}
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value = value.Right
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}
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a := nod(OINDEX, vauto, nodintconst(index))
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@ -1250,7 +1256,10 @@ func initplan(n *Node) {
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var k int64
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for _, a := range n.List.Slice() {
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if a.Op == OKEY {
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k = nonnegintconst(a.Left)
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k = indexconst(a.Left)
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if k < 0 {
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Fatalf("initplan arraylit: invalid index %v", a.Left)
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}
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a = a.Right
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}
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addvalue(p, k*n.Type.Elem().Width, a)
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@ -1260,7 +1269,7 @@ func initplan(n *Node) {
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case OSTRUCTLIT:
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for _, a := range n.List.Slice() {
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if a.Op != OSTRUCTKEY {
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Fatalf("initplan fixedlit")
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Fatalf("initplan structlit")
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}
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addvalue(p, a.Xoffset, a.Left)
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}
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@ -3073,10 +3073,16 @@ func typecheckcomplit(n *Node) (res *Node) {
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if l.Op == OKEY {
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l.Left = typecheck(l.Left, ctxExpr)
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evconst(l.Left)
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i = nonnegintconst(l.Left)
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if i < 0 && !l.Left.Diag() {
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yyerror("index must be non-negative integer constant")
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l.Left.SetDiag(true)
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i = indexconst(l.Left)
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if i < 0 {
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if !l.Left.Diag() {
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if i == -2 {
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yyerror("index too large")
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} else {
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yyerror("index must be non-negative integer constant")
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}
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l.Left.SetDiag(true)
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}
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i = -(1 << 30) // stay negative for a while
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}
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vp = &l.Right
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@ -1305,7 +1305,11 @@ opswitch:
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}
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// var arr [r]T
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// n = arr[:l]
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t = types.NewArray(t.Elem(), nonnegintconst(r)) // [r]T
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i := indexconst(r)
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if i < 0 {
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Fatalf("walkexpr: invalid index %v", r)
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}
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t = types.NewArray(t.Elem(), i) // [r]T
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var_ := temp(t)
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a := nod(OAS, var_, nil) // zero temp
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a = typecheck(a, ctxStmt)
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10
test/fixedbugs/issue23781.go
Normal file
10
test/fixedbugs/issue23781.go
Normal file
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@ -0,0 +1,10 @@
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// +build amd64
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// compile
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package p
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var _ = []int{1 << 31: 1} // ok on machines with 64bit int
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