cmd/compile/internal/gc: fix invalid positions for sink nodes in esc.go

Make OAS2 and OAS2FUNC sink locations point to the assignment position, not the nth LHS position. Fixes #26987 Change-Id: Ibeb9df2da754da8b6638fe1e49e813f37515c13c Reviewed-on: https://go-review.googlesource.com/129315 Run-TryBot: Iskander Sharipov <[email protected]> TryBot-Result: Gobot Gobot <[email protected]> Reviewed-by: David Chase <[email protected]> Reviewed-by: Cherry Zhang <[email protected]>
cloudflare · Sep 3, 2018 · 67ac554 · 67ac554
1 parent 5ed30d8
commit 67ac554
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Showing 2 changed files with 22 additions and 2 deletions.
diff --git a/src/cmd/compile/internal/gc/esc.go b/src/cmd/compile/internal/gc/esc.go
@@ -886,8 +886,9 @@ opSwitch:
  case OAS2: // x,y = a,b
  if n.List.Len() == n.Rlist.Len() {
  rs := n.Rlist.Slice()
+ where := n
  for i, n := range n.List.Slice() {
- e.escassignWhyWhere(n, rs[i], "assign-pair", n)
+ e.escassignWhyWhere(n, rs[i], "assign-pair", where)
  }
  }
 
@@ -928,11 +929,12 @@ opSwitch:
  // esccall already done on n.Rlist.First(). tie it's Retval to n.List
  case OAS2FUNC: // x,y = f()
  rs := e.nodeEscState(n.Rlist.First()).Retval.Slice()
+ where := n
  for i, n := range n.List.Slice() {
  if i >= len(rs) {
  break
  }
- e.escassignWhyWhere(n, rs[i], "assign-pair-func-call", n)
+ e.escassignWhyWhere(n, rs[i], "assign-pair-func-call", where)
  }
  if n.List.Len() != len(rs) {
  Fatalf("esc oas2func")

diff --git a/test/escape_because.go b/test/escape_because.go
@@ -125,6 +125,24 @@ func f14() {
  _, _ = s1, s2
 }
 
+func leakParams(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2 level=0$" "from ~r2 \(return\) at escape_because.go:129$" "leaking param: p2 to result ~r3 level=0$" "from ~r3 \(return\) at escape_because.go:129$"
+ return p1, p2
+}
+
+func leakThroughOAS2() {
+ // See #26987.
+ i := 0 // ERROR "moved to heap: i$"
+ j := 0 // ERROR "moved to heap: j$"
+ sink, sink = &i, &j // ERROR "&i escapes to heap$" "from sink \(assign-pair\) at escape_because.go:136$" "from &i \(interface-converted\) at escape_because.go:136$" "&j escapes to heap$" "from &j \(interface-converted\) at escape_because.go:136"
+}
+
+func leakThroughOAS2FUNC() {
+ // See #26987.
+ i := 0 // ERROR "moved to heap: i$"
+ j := 0
+ sink, _ = leakParams(&i, &j) // ERROR "&i escapes to heap$" "&j does not escape$" "from .out0 \(passed-to-and-returned-from-call\) at escape_because.go:143$" "from sink \(assign-pair-func-call\) at escape_because.go:143$"
+}
+
 // The list below is all of the why-escapes messages seen building the escape analysis tests.
 /*
  for i in escape*go ; do echo compile $i; go build -gcflags '-l -m -m' $i >& `basename $i .go`.log ; done