cmd/compile/internal/gc: add nil check for closure call on wasm

This commit adds an explicit nil check for closure calls on wasm,
so calling a nil func causes a proper panic instead of crashing on the
WebAssembly level.

Change-Id: I6246844f316677976cdd420618be5664444c25ae
Reviewed-on: https://go-review.googlesource.com/127759
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 553713a1e9bbba543ee9a786e7e861249b9d8505..af43da627546189294abce9bfea4db4b3447b0aa 100644 (file)
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -3515,6 +3515,10 @@ func (s *state) call(n *Node, k callKind) *ssa.Value {
                        break
                }
                closure = s.expr(fn)
+               if thearch.LinkArch.Family == sys.Wasm {
+                       // TODO(neelance): On other architectures this should be eliminated by the optimization steps
+                       s.nilCheck(closure)
+               }
        case OCALLMETH:
                if fn.Op != ODOTMETH {
                        Fatalf("OCALLMETH: n.Left not an ODOTMETH: %v", fn)

diff --git a/test/closure4.go b/test/closure4.go
new file mode 100644 (file)
index 0000000..ec4e0a1
--- /dev/null
+++ b/test/closure4.go
@@ -0,0 +1,21 @@
+// run
+
+// Copyright 2018 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.
+
+// Check that calling a nil func causes a proper panic.
+
+package main
+
+func main() {
+       defer func() {
+               err := recover()
+               if err == nil {
+                       panic("panic expected")
+               }
+       }()
+
+       var f func()
+       f()
+}