Skip to content

SimplifyGlobals: Do not switch a get to use a global of another type #6605

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.

Sign up for GitHub

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

Merged
kripken merged 1 commit into from
May 20, 2024
Merged

SimplifyGlobals: Do not switch a get to use a global of another type #6605

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion src/passes/SimplifyGlobals.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -317,7 +317,14 @@ struct GlobalUseModifier : public WalkerPass<PostWalker<GlobalUseModifier>> {
void visitGlobalGet(GlobalGet* curr) {
auto iter = copiedParentMap->find(curr->name);
if (iter != copiedParentMap->end()) {
curr->name = iter->second;
auto original = iter->second;
// Only apply this optimization if the global we are switching to has the
// right type for us.
// TODO: We could also allow it to be more refined, but would then need to
// refinalize.
if (getModule()->getGlobal(original)->type == curr->type) {
curr->name = original;
}
}
}

Expand Down
24 changes: 24 additions & 0 deletions test/lit/passes/simplify-globals-gc.wast
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -31,3 +31,27 @@
)
)

(module
;; CHECK: (type $struct (struct ))
(type $struct (struct ))

;; CHECK: (type $1 (func (result anyref)))

;; CHECK: (global $a (ref $struct) (struct.new_default $struct))
(global $a (ref $struct) (struct.new_default $struct))
;; CHECK: (global $b (ref $struct) (global.get $a))
(global $b (ref $struct) (global.get $a))
Copy link
Member

@tlively tlively May 18, 2024

Choose a reason for hiding this comment

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

What is the role of $b in this test?

Copy link
Member Author

@kripken kripken May 20, 2024

Choose a reason for hiding this comment

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

Just to be comprehensive. $c is equal to both $a and $b but in different ways (it reads $a, but it has equal content to $b). I don't think we optimize both cases atm but this would handle things if we ever did.

;; CHECK: (global $c (ref null $struct) (global.get $a))
(global $c (ref null $struct) (global.get $a))

;; CHECK: (func $get-c (type $1) (result anyref)
;; CHECK-NEXT: (global.get $c)
;; CHECK-NEXT: )
(func $get-c (result anyref)
;; $c has a less-refined type than the other two. We do not switch this to
;; get from either $a or $b because of that, but we could if we also
;; refinalized TODO
(global.get $c)
)
)