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author | Cuong Manh Le <cuong.manhle.vn@gmail.com> | 2022-09-06 12:54:54 +0700 |
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committer | Gopher Robot <gobot@golang.org> | 2022-09-06 22:14:56 +0000 |
commit | c82304b7129d7e675ff010d54f58d039235e4802 (patch) | |
tree | 67adef2ab68750287b0090ccb232bce6e597c570 /src/cmd/compile/internal/devirtualize/devirtualize.go | |
parent | 812fd2fe70112209557c4f6392ab8eaee6f68dda (diff) | |
download | go-git-c82304b7129d7e675ff010d54f58d039235e4802.tar.gz |
cmd/compile: do not devirtualize defer/go calls
For defer/go calls, the function/method value are evaluated immediately.
So after devirtualizing, it may trigger a panic when implicitly deref
a nil pointer receiver, causing the program behaves unexpectedly.
It's safer to not devirtualizing defer/go calls at all.
Fixes #52072
Change-Id: I562c2860e3e577b36387dc0a12ae5077bc0766bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/428495
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Diffstat (limited to 'src/cmd/compile/internal/devirtualize/devirtualize.go')
-rw-r--r-- | src/cmd/compile/internal/devirtualize/devirtualize.go | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/devirtualize/devirtualize.go b/src/cmd/compile/internal/devirtualize/devirtualize.go index b620470b0e..7350a6f171 100644 --- a/src/cmd/compile/internal/devirtualize/devirtualize.go +++ b/src/cmd/compile/internal/devirtualize/devirtualize.go @@ -17,9 +17,25 @@ import ( // Func devirtualizes calls within fn where possible. func Func(fn *ir.Func) { ir.CurFunc = fn + + // For promoted methods (including value-receiver methods promoted to pointer-receivers), + // the interface method wrapper may contain expressions that can panic (e.g., ODEREF, ODOTPTR, ODOTINTER). + // Devirtualization involves inlining these expressions (and possible panics) to the call site. + // This normally isn't a problem, but for go/defer statements it can move the panic from when/where + // the call executes to the go/defer statement itself, which is a visible change in semantics (e.g., #52072). + // To prevent this, we skip devirtualizing calls within go/defer statements altogether. + goDeferCall := make(map[*ir.CallExpr]bool) ir.VisitList(fn.Body, func(n ir.Node) { - if call, ok := n.(*ir.CallExpr); ok { - Call(call) + switch n := n.(type) { + case *ir.GoDeferStmt: + if call, ok := n.Call.(*ir.CallExpr); ok { + goDeferCall[call] = true + } + return + case *ir.CallExpr: + if !goDeferCall[n] { + Call(n) + } } }) } |