# Owner(s): ["oncall: jit"]

import torch
from torch.testing import FileCheck
from torch.testing._internal.jit_utils import JitTestCase, make_global


class TestDCE(JitTestCase):
    def test_setattr_no_aliasdb(self):
        class Net(torch.nn.Module):
            def __init__(self) -> None:
                super().__init__()
                self.x = torch.empty([2, 2])

            def forward(self):
                x = torch.rand([3, 3])
                self.x = x

        net = torch.jit.script(Net())

        FileCheck().check("prim::SetAttr").run(net.graph)

    def test_setattr_removed(self):
        @torch.jit.script
        class Thing1:
            def __init__(self) -> None:
                self.x = torch.zeros([2, 2])

        make_global(Thing1)

        class Thing2(torch.nn.Module):
            def forward(self):
                x = torch.rand([2, 2])
                y = torch.rand([2, 2])
                t1 = Thing1()
                t1.x = x
                return y

        unscripted = Thing2()

        t2 = torch.jit.script(unscripted)
        t2.eval()

        # freezing inlines t1.__init__(), after which DCE can occur.
        t2 = torch.jit.freeze(t2)
        FileCheck().check_not("prim::SetAttr").run(t2.graph)
