Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[compiler] Add fallthrough to branch terminal #30814

Merged
merged 4 commits into from
Aug 28, 2024

Conversation

josephsavona
Copy link
Contributor

@josephsavona josephsavona commented Aug 26, 2024

Stack from ghstack (oldest at bottom):

Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, foo?.bar?.baz creates terminals along the lines of:

bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...

Without a fallthrough on branch terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

[ghstack-poisoned]
Copy link

vercel bot commented Aug 26, 2024

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name Status Preview Comments Updated (UTC)
react-compiler-playground ✅ Ready (Inspect) Visit Preview 💬 Add feedback Aug 28, 2024 6:12pm

Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

[ghstack-poisoned]
Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

[ghstack-poisoned]
Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

[ghstack-poisoned]
Comment on lines +512 to +514
case 'logical':
case 'sequence':
case 'ternary': {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah I see, I'm guessing that this is to support something like useMemo(..., [(a ?? b)?.c]). Not technically necessary for DropManualMemo as we're only tracking named variables, but this makes sense to have in a utility function

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

yup exactly

Comment on lines +502 to +504
if (last !== undefined && last.value.kind === 'StoreLocal') {
optionals.add(last.value.value.identifier.id);
}
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This feels slightly weird since DropManualMemo runs before we enter ssa, so both consequent (the optional read) and alternate (undefined) write to the same identifier ID. There is also no phi join, so reads to the OptionalExpression rvalue is also guaranteed to use the same identifier ID (and this works)

(I'm guessing that passes after SSA will need to track phis as well -- reading the rest of the stack now)

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yeah I looked at using the phi to figure out which values is optional. First, as you noted we aren't in SSA so we don't have phis yet. Second, the phis end up in weird places for nested optionals, because with nested optionals the alternate actually goes to the outermost fallthrough. So we just look at where the consequent assigns to in order to figure out what the optional value was.

@josephsavona josephsavona merged commit 00d44be into gh/josephsavona/50/base Aug 28, 2024
19 checks passed
josephsavona added a commit that referenced this pull request Aug 28, 2024
Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

ghstack-source-id: d48c6232899864716eef71798a278b487d30eafc
Pull Request resolved: #30814
@josephsavona josephsavona deleted the gh/josephsavona/50/head branch August 28, 2024 22:59
nivemula pushed a commit to nivemula/Java that referenced this pull request Sep 5, 2024
Branch terminals didn't have a fallthrough because they correspond to an outer terminal (optional, logical, etc) that has the "real" fallthrough. But understanding how branch terminals correspond to these outer terminals requires knowing the branch fallthrough. For example, `foo?.bar?.baz` creates terminals along the lines of:

```
bb0:
  optional fallthrough=bb4
bb1:
  optional fallthrough=bb3
bb2:
  ...
  branch ... (fallthrough=bb3)

...

bb3:
  ...
  branch ... (fallthrough=bb4)

...

bb4:
  ...
```

Without a fallthrough on `branch` terminals, it's unclear that the optional from bb0 has its branch node in bb3. With the fallthroughs, we can see look for a branch with the same fallthrough as the outer optional terminal to match them up.

ghstack-source-id: 064178d377e1eb8a308f4d2f0d3f0132817a5b56
Pull Request resolved: facebook/react#30814
gnoff pushed a commit to vercel/next.js that referenced this pull request Sep 12, 2024
**breaking change for canary users: Bumps peer dependency of React from
`19.0.0-rc-7771d3a7-20240827` to `19.0.0-rc-94e652d5-20240912`**

[diff
facebook/react@7771d3a7...94e652d5](facebook/react@7771d3a...94e652d)

<details>
<summary>React upstream changes</summary>

- facebook/react#30952
- facebook/react#30950
- facebook/react#30946
- facebook/react#30934
- facebook/react#30947
- facebook/react#30945
- facebook/react#30938
- facebook/react#30936
- facebook/react#30879
- facebook/react#30888
- facebook/react#30931
- facebook/react#30930
- facebook/react#30832
- facebook/react#30929
- facebook/react#30926
- facebook/react#30925
- facebook/react#30905
- facebook/react#30900
- facebook/react#30910
- facebook/react#30906
- facebook/react#30899
- facebook/react#30919
- facebook/react#30708
- facebook/react#30907
- facebook/react#30897
- facebook/react#30896
- facebook/react#30895
- facebook/react#30887
- facebook/react#30889
- facebook/react#30893
- facebook/react#30892
- facebook/react#30891
- facebook/react#30882
- facebook/react#30881
- facebook/react#30870
- facebook/react#30849
- facebook/react#30878
- facebook/react#30865
- facebook/react#30869
- facebook/react#30875
- facebook/react#30800
- facebook/react#30762
- facebook/react#30831
- facebook/react#30866
- facebook/react#30853
- facebook/react#30850
- facebook/react#30847
- facebook/react#30842
- facebook/react#30837
- facebook/react#30848
- facebook/react#30844
- facebook/react#30839
- facebook/react#30802
- facebook/react#30841
- facebook/react#30827
- facebook/react#30826
- facebook/react#30825
- facebook/react#30824
- facebook/react#30840
- facebook/react#30838
- facebook/react#30836
- facebook/react#30819
- facebook/react#30816
- facebook/react#30814
- facebook/react#30813
- facebook/react#30812
- facebook/react#30811

</details>

---------

Co-authored-by: vercel-release-bot <[email protected]>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
CLA Signed React Core Team Opened by a member of the React Core Team
Projects
None yet
Development

Successfully merging this pull request may close these issues.

3 participants