We have the following subgraph
48 ConP === 0
61253 Phi === 228 _ 48
61252 InlineType === _ 61253 61254 61255 61256
61248 Phi === 242 61252 61253
`Phi` 61248 is transformed and `PushInlineTypeDown::do_transform` runs.
A new value type is created:
61259 Phi === 242 1 1
61258 InlineType === _ 61259 61260 61261 61262
```
First input of `Phi` 61248 is processed:
61259 Phi === 242 61253 1
61258 InlineType === _ 61259 61260 61261 61262
The second input of the `Phi` 61248, `Phi` 61253, is processed which
causes a recursive call to `PushInlineTypeDown::do_transform`. A value
type is created:
61264 Phi === 228 _ 1
61263 InlineType === _ 61264 61265 61266 61267
In the uses of `Phi` 61253, `Phi` 61253 is replaced by `InlineType`
61263.
One such as use is`Phi` 61259. As a consequence, the value type of the
caller of this `PushInlineTypeDown::do_transform` is modified:
61259 Phi === 242 61263 1
61258 InlineType === _ 61259 61260 61261 61262
`PushInlineTypeDown::do_transform` for `Phi` 61253 runs to completion:
61264 Phi === 228 _ 48
61263 InlineType === _ 61264 61265 61266 61267
`PushInlineTypeDown::do_transform` for `Phi` 61248 runs to completion:
48 ConP === 0
61264 Phi === 228 _ 48
61263 InlineType === _ 61264 61265 61266 61267
61259 Phi === 242 61263 61264
61258 InlineType === _ 61259 61260 61261 61262
Which is a shape identical to what `PushInlineTypeDown::do_transform`
started from. Transformation then happens with `Phi` 61259 which
produces the same shape etc.
Things go wrong, I think, because of this code in
`PushInlineTypeDown::do_transform`:
if (_can_reshape) {
// Replace phi right away to be able to use the inline
// type node when reaching the phi again through data loops.
PhaseIterGVN* igvn = _phase->is_IterGVN();
for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
Node* u = phi->fast_out(i);
igvn->rehash_node_delayed(u);
imax -= u->replace_edge(phi, vt);
--i;
}
igvn->rehash_node_delayed(phi);
assert(phi->outcnt() == 0, "should be dead now");
}
because it changes an already processed input of a `Phi` and adds an
`InlineType` where there was none. From the comment, the goal is to
handle cases where we run into that same `Phi` when
`PushInlineTypeDown::do_transform` continues execution and not create
a new `InlineType` node. To do that, I propose recording that `vt` is
created for `phi` rather than changing the graph.
---------
- [x] I confirm that I make this contribution in accordance with the [OpenJDK
Interim AI Policy](https://openjdk.org/legal/ai).
-------------
Commit messages:
- whitespaces
- Merge branch 'lworld' into JDK-8386676
- more
- more
- more
Changes: https://git.openjdk.org/valhalla/pull/2600/files
Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2600&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8386676
Stats: 95 lines in 2 files changed: 83 ins; 7 del; 5 mod
Patch: https://git.openjdk.org/valhalla/pull/2600.diff
Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2600/head:pull/2600
PR: https://git.openjdk.org/valhalla/pull/2600
