cmd/link: disable weak reference in itab if build with "-linkshared"
When build with "-linkshared", we can't tell if the interface method will be used or not. It can be used in shared library.
Fixes #47873
Change-Id: Iba12812f199b7679cf2fd41a304268d6d6dd03c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/350189
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Alexander Rakoczy <alex@golang.org>
diff --git a/misc/cgo/testshared/shared_test.go b/misc/cgo/testshared/shared_test.go
index 1bd89bc..672811f 100644
--- a/misc/cgo/testshared/shared_test.go
+++ b/misc/cgo/testshared/shared_test.go
@@ -1070,3 +1070,11 @@
goCmd(t, "install", "-buildmode=shared", "-linkshared", "./issue44031/b")
goCmd(t, "run", "-linkshared", "./issue44031/main")
}
+
+// Test that we use a variable from shared libraries (which implement an
+// interface in shared libraries.). A weak reference is used in the itab
+// in main process. It can cause unreacheble panic. See issue 47873.
+func TestIssue47873(t *testing.T) {
+ goCmd(t, "install", "-buildmode=shared", "-linkshared", "./issue47837/a")
+ goCmd(t, "run", "-linkshared", "./issue47837/main")
+}
diff --git a/misc/cgo/testshared/testdata/issue47837/a/a.go b/misc/cgo/testshared/testdata/issue47837/a/a.go
new file mode 100644
index 0000000..68588ed
--- /dev/null
+++ b/misc/cgo/testshared/testdata/issue47837/a/a.go
@@ -0,0 +1,19 @@
+// Copyright 2021 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 a
+
+type A interface {
+ M()
+}
+
+//go:noinline
+func TheFuncWithArgA(a A) {
+ a.M()
+}
+
+type ImplA struct{}
+
+//go:noinline
+func (A *ImplA) M() {}
diff --git a/misc/cgo/testshared/testdata/issue47837/main/main.go b/misc/cgo/testshared/testdata/issue47837/main/main.go
new file mode 100644
index 0000000..77c6f34
--- /dev/null
+++ b/misc/cgo/testshared/testdata/issue47837/main/main.go
@@ -0,0 +1,14 @@
+// Copyright 2021 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 main
+
+import (
+ "testshared/issue47837/a"
+)
+
+func main() {
+ var vara a.ImplA
+ a.TheFuncWithArgA(&vara)
+}
diff --git a/src/cmd/link/internal/ld/deadcode.go b/src/cmd/link/internal/ld/deadcode.go
index 0221024..79acd73 100644
--- a/src/cmd/link/internal/ld/deadcode.go
+++ b/src/cmd/link/internal/ld/deadcode.go
@@ -134,7 +134,9 @@
methods = methods[:0]
for i := 0; i < relocs.Count(); i++ {
r := relocs.At(i)
- if r.Weak() {
+ // When build with "-linkshared", we can't tell if the interface
+ // method in itab will be used or not. Ignore the weak attribute.
+ if r.Weak() && !(d.ctxt.linkShared && d.ldr.IsItab(symIdx)) {
continue
}
t := r.Type()
