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cmd/compile: handle unsafe.Pointer(f()) correctly

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Previously statements like

    f(unsafe.Pointer(g()), int(h()))

would be reordered into a sequence of statements like

    autotmp_g := g()
    autotmp_h := h()
    f(unsafe.Pointer(autotmp_g), int(autotmp_h))

which can leave g's temporary value on the stack as a uintptr, rather
than an unsafe.Pointer. Instead, recognize uintptr-to-unsafe.Pointer
conversions when reordering function calls to instead produce:

    autotmp_g := unsafe.Pointer(g())
    autotmp_h := h()
    f(autotmp_g, int(autotmp_h))

Fixes #15329.

Change-Id: I2cdbd89d233d0d5c94791513a9fd5fd958d11ed5
Reviewed-on: https://go-review.googlesource.com/22273
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Matthew Dempsky 2016-04-19 15:02:06 -07:00 • committed by Russ Cox
parent c6a5b3602a
commit c65647d620
2 changed files with 93 additions and 0 deletions
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14
src/cmd/compile/internal/gc/order.go
View file

@ -1082,6 +1082,20 @@ func orderexpr(n *Node, order *Order, lhs *Node) *Node {
n.Left = orderaddrtemp(n.Left, order)
}
case OCONVNOP:
if n.Type.IsKind(TUNSAFEPTR) && n.Left.Type.IsKind(TUINTPTR) && (n.Left.Op == OCALLFUNC || n.Left.Op == OCALLINTER || n.Left.Op == OCALLMETH) {
// When reordering unsafe.Pointer(f()) into a separate
// statement, the conversion and function call must stay
// together. See golang.org/issue/15329.
orderinit(n.Left, order)
ordercall(n.Left, order)
if lhs == nil || lhs.Op != ONAME || instrumenting {
n = ordercopyexpr(n, n.Type, order, 0)
}
} else {
n.Left = orderexpr(n.Left, order, nil)
}
case OANDAND, OOROR:
mark := marktemp(order)
n.Left = orderexpr(n.Left, order, nil)