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| author | Matthew Dempsky <mdempsky@google.com> | 2021-01-21 19:27:12 -0800 |
|---|---|---|
| committer | Matthew Dempsky <mdempsky@google.com> | 2021-01-25 23:54:36 +0000 |
| commit | deaf29a8a8ab76613bf0d5d97c4e31bfbdc4c4e9 (patch) | |
| tree | eceb1c0bc805e7e82536d7ba77ad5b49dfd48031 /src | |
| parent | ad2ca26a521a5a642f51c3ef8e3004c9ce7af5aa (diff) | |
| download | go-deaf29a8a8ab76613bf0d5d97c4e31bfbdc4c4e9.tar.gz go-deaf29a8a8ab76613bf0d5d97c4e31bfbdc4c4e9.zip | |
cmd/compile: fix order-of-assignment issue w/ defers
CL 261677 fixed a logic issue in walk's alias detection, where it was
checking the RHS expression instead of the LHS expression when trying
to determine the kind of assignment. However, correcting this exposed
a latent issue with assigning to result parameters in functions with
defers, where an assignment could become visible earlier than intended
if a later expression could panic.
Fixes #43835.
Change-Id: I061ced125e3896e26d65f45b28c99db2c8a74a8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/285633
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/compile/internal/gc/walk.go | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go index a7b6e7fcb3c..2133a160b2b 100644 --- a/src/cmd/compile/internal/gc/walk.go +++ b/src/cmd/compile/internal/gc/walk.go @@ -267,7 +267,7 @@ func walkstmt(n *Node) *Node { if n.List.Len() == 0 { break } - if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) { + if (Curfn.Type.FuncType().Outnamed && n.List.Len() > 1) || paramoutheap(Curfn) || Curfn.Func.HasDefer() { // assign to the function out parameters, // so that reorder3 can fix up conflicts var rl []*Node @@ -2233,7 +2233,15 @@ func aliased(r *Node, all []*Node) bool { memwrite = true continue - case PAUTO, PPARAM, PPARAMOUT: + case PPARAMOUT: + // Assignments to a result parameter in a function with defers + // becomes visible early if evaluation of any later expression + // panics (#43835). + if Curfn.Func.HasDefer() { + return true + } + fallthrough + case PAUTO, PPARAM: if l.Name.Addrtaken() { memwrite = true continue |