reflect: keep pointer in aggregate-typed args live in Call

When register ABI is used, reflect.Value.Call prepares the call
arguments in a memory representation of the argument registers.
It has special handling to keep the pointers in arguments live.
Currently, this handles pointer-typed arguments. But when an
argument is an aggregate-type that contains pointers and passed
in registers, it currently doesn't keep the pointers live. Do
so in this CL.

May fix #49363.

Change-Id: Ic6a0c5fdf9375ef02f7c03fbe9345e2e98c9353d
Reviewed-on: https://go-review.googlesource.com/c/go/+/363358
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/src/reflect/all_test.go b/src/reflect/all_test.go
index acc09962a0..8c51d8ec26 100644
--- a/src/reflect/all_test.go
+++ b/src/reflect/all_test.go
@@ -6478,6 +6478,29 @@ func TestCallMethodJump(t *testing.T) {
 	*CallGC = false
 }
 
+func TestCallArgLive(t *testing.T) {
+	type T struct{ X, Y *string } // pointerful aggregate
+
+	F := func(t T) { *t.X = "ok" }
+
+	// In reflect.Value.Call, trigger a garbage collection in reflect.call
+	// between marshaling argument and the actual call.
+	*CallGC = true
+
+	x := new(string)
+	runtime.SetFinalizer(x, func(p *string) {
+		if *p != "ok" {
+			t.Errorf("x dead prematurely")
+		}
+	})
+	v := T{x, nil}
+
+	ValueOf(F).Call([]Value{ValueOf(v)})
+
+	// Stop garbage collecting during reflect.call.
+	*CallGC = false
+}
+
 func TestMakeFuncStackCopy(t *testing.T) {
 	target := func(in []Value) []Value {
 		runtime.GC()