[Relay] error in type inference #1984
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| // slow path with path compression. | ||
| TypeNode* root = this; | ||
| while (root->parent != nullptr) { | ||
| CHECK(root->parent != root) << "should not refer back to itself"; |
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Why not return root if you detect root->parent == root? This way, you won't throw (unnecessary?) exception (BTW the new unit test failed). The following snippet seems normal program to me and we probably should support it?
"""Program:
def f(x : Tensor[(10, 10), f32]) {
return log(x);
}
"""
from tvm import relay
a = relay.TypeVar("a")
x = relay.var("x", a)
sb = relay.ScopeBuilder()
f = relay.Function([x], x)
fx = relay.Call(f, [x])
assert relay.ir_pass.infer_type(x).checked_type == a
assert relay.ir_pass.infer_type(f).checked_type == relay.FuncType([a], a)
assert relay.ir_pass.infer_type(fx).checked_type == aThere was a problem hiding this comment.
yes, I did, and it is breaking invariant somewhere else (so did not get merged).
see #1983
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It is supposed to fail. This is more of a issue (but issue wont get ci).
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Oh OK, I'm interested in how such self reference structure is created cause the test case is trivial. FYI, I tried my fix and it correctly pass the above tests.
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That's good. I have no time to investigate into type inference internal right now, so we might have this on hold until I have more time slot (after 20days). IDK.
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Actually for this particular case, it's simply because we don't check type equality before we do unification(and we should always do the quality check before we try to unify them):
https://github.com/dmlc/tvm/blob/cbf4fdbbbf4993849342906722e776d332f2e97d/src/relay/pass/type_solver.cc#L71
I have a test test that failed master and works after the fix. Could you help review?
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This problem is due to there not being an occurs check: https://en.wikipedia.org/wiki/Occurs_check
|
fixed by #2012 |
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