From de1c934b9709728b15cc821a055155ee13e1d0ab Mon Sep 17 00:00:00 2001 From: Cuong Manh Le Date: Fri, 20 Aug 2021 11:38:54 +0700 Subject: cmd/compile: fix checkptr false positive for (*[Big]T)(ptr)[:n:n] pattern The checkptr instrumentation is currently inserted before slice operation has validated that n <= Big. So instead of panic, checkptr have false positive throws. To fix this, just insert the checkptr instrumentation after the bound checking during SSA generation. Fixes #46938 Change-Id: I9dbf84441c711842ccc883f3654ca8766ac696d8 Reviewed-on: https://go-review.googlesource.com/c/go/+/343972 Trust: Cuong Manh Le Run-TryBot: Cuong Manh Le TryBot-Result: Go Bot Reviewed-by: Matthew Dempsky --- src/cmd/compile/internal/ir/expr.go | 9 +++++---- src/cmd/compile/internal/ssagen/ssa.go | 3 +++ src/cmd/compile/internal/walk/convert.go | 13 +++++++++++-- src/cmd/compile/internal/walk/expr.go | 2 +- 4 files changed, 20 insertions(+), 7 deletions(-) (limited to 'src') diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go index f526d987a7..41de6bd61b 100644 --- a/src/cmd/compile/internal/ir/expr.go +++ b/src/cmd/compile/internal/ir/expr.go @@ -570,10 +570,11 @@ func (*SelectorExpr) CanBeNtype() {} // A SliceExpr is a slice expression X[Low:High] or X[Low:High:Max]. type SliceExpr struct { miniExpr - X Node - Low Node - High Node - Max Node + X Node + Low Node + High Node + Max Node + CheckPtrCall *CallExpr } func NewSliceExpr(pos src.XPos, op Op, x, low, high, max Node) *SliceExpr { diff --git a/src/cmd/compile/internal/ssagen/ssa.go b/src/cmd/compile/internal/ssagen/ssa.go index 39d3b206ac..0a48f6b704 100644 --- a/src/cmd/compile/internal/ssagen/ssa.go +++ b/src/cmd/compile/internal/ssagen/ssa.go @@ -3090,6 +3090,9 @@ func (s *state) expr(n ir.Node) *ssa.Value { k = s.expr(n.Max) } p, l, c := s.slice(v, i, j, k, n.Bounded()) + if n.CheckPtrCall != nil { + s.stmt(n.CheckPtrCall) + } return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c) case ir.OSLICESTR: diff --git a/src/cmd/compile/internal/walk/convert.go b/src/cmd/compile/internal/walk/convert.go index 27a07ce4b6..f724ca7cae 100644 --- a/src/cmd/compile/internal/walk/convert.go +++ b/src/cmd/compile/internal/walk/convert.go @@ -413,11 +413,15 @@ func byteindex(n ir.Node) ir.Node { return n } -func walkCheckPtrAlignment(n *ir.ConvExpr, init *ir.Nodes, count ir.Node) ir.Node { +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) @@ -435,7 +439,12 @@ func walkCheckPtrAlignment(n *ir.ConvExpr, init *ir.Nodes, count ir.Node) ir.Nod } n.X = cheapExpr(n.X, init) - init.Append(mkcall("checkptrAlignment", nil, init, typecheck.ConvNop(n.X, types.Types[types.TUNSAFEPTR]), reflectdata.TypePtr(elem), typecheck.Conv(count, types.Types[types.TUINTPTR]))) + 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 } diff --git a/src/cmd/compile/internal/walk/expr.go b/src/cmd/compile/internal/walk/expr.go index 26e225440a..c04998137b 100644 --- a/src/cmd/compile/internal/walk/expr.go +++ b/src/cmd/compile/internal/walk/expr.go @@ -824,7 +824,7 @@ 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.Max) + n.X = walkCheckPtrAlignment(n.X.(*ir.ConvExpr), init, n) } if n.Op().IsSlice3() { -- cgit v1.2.3-54-g00ecf