cmd/compile: check ODEREF for safe lhs in assignment during static init

For #66585

Change-Id: Iddc407e3ef4c3b6ecf5173963b66b3e65e43c92d
Reviewed-on: https://go-review.googlesource.com/c/go/+/575336
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@golang.org>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

diff --git a/src/cmd/compile/internal/staticinit/sched.go b/src/cmd/compile/internal/staticinit/sched.go
index 4191f6997ebcf47af0475bf7479271bb1fd2ace5..1f119920e97101d8c5e0538cd771c2292d6f5952 100644 (file)
--- a/src/cmd/compile/internal/staticinit/sched.go
+++ b/src/cmd/compile/internal/staticinit/sched.go
@@ -881,7 +881,13 @@ func mayModifyPkgVar(n ir.Node) bool {
        // safeLHS reports whether the assigned-to variable lhs is either a
        // local variable or a global from another package.
        safeLHS := func(lhs ir.Node) bool {
-               v, ok := ir.OuterValue(lhs).(*ir.Name)
+               outer := ir.OuterValue(lhs)
+               // "*p = ..." should be safe if p is a local variable.
+               // TODO: Should ir.OuterValue handle this?
+               for outer.Op() == ir.ODEREF {
+                       outer = outer.(*ir.StarExpr).X
+               }
+               v, ok := outer.(*ir.Name)
                return ok && v.Op() == ir.ONAME && !(v.Class == ir.PEXTERN && v.Sym().Pkg == types.LocalPkg)
        }
 

diff --git a/test/codegen/issue66585.go b/test/codegen/issue66585.go
new file mode 100644 (file)
index 0000000..32a180b
--- /dev/null
+++ b/test/codegen/issue66585.go
@@ -0,0 +1,24 @@
+// asmcheck
+
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+var x = func() int {
+       n := 0
+       f(&n)
+       return n
+}()
+
+func f(p *int) {
+       *p = 1
+}
+
+var y = 1
+
+// z can be static initialized.
+//
+// amd64:-"MOVQ"
+var z = y