Skip to content

Fix OptimizeInstructions on unreachable GC RMWs #8485

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
tlively merged 1 commit into from
Mar 18, 2026
+71 −0
Merged

Fix OptimizeInstructions on unreachable GC RMWs #8485

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: 9 additions & 0 deletions src/passes/OptimizeInstructions.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2003,6 +2003,10 @@ struct OptimizeInstructions
if (curr->ref->type.getHeapType().isShared()) {
return;
}
if (curr->type == Type::unreachable) {
// Leave this to DCE.
return;
}

// Lower the RMW to its more basic operations. Breaking the atomic
// operation into several non-atomic operations is safe because no other
Expand Down Expand Up @@ -2100,6 +2104,11 @@ struct OptimizeInstructions
return;
}

if (curr->type == Type::unreachable) {
// Leave this to DCE.
return;
}

// Just like other RMW operations, lower to basic operations when operating
// on unshared memory.
auto ref = builder.addVar(getFunction(), curr->ref->type);
Expand Down
62 changes: 62 additions & 0 deletions test/lit/passes/optimize-instructions-struct-rmw.wast
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1308,4 +1308,66 @@
(i32.const 2)
)
)

;; CHECK: (func $struct-rmw-unreachable-lowering (type $16) (param $0 (ref null $unshared-i32)) (result i32)
;; CHECK-NEXT: (struct.atomic.rmw.add $unshared-i32 0
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $struct-rmw-unreachable-lowering (param (ref null $unshared-i32)) (result i32)
;; Check that we skip lowering if an operand is unreachable.
(struct.atomic.rmw.add $unshared-i32 0
(local.get 0)
(unreachable)
)
)

;; CHECK: (func $struct-cmpxchg-unreachable-lowering (type $16) (param $0 (ref null $unshared-i32)) (result i32)
;; CHECK-NEXT: (struct.atomic.rmw.cmpxchg $unshared-i32 0
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $struct-cmpxchg-unreachable-lowering (param (ref null $unshared-i32)) (result i32)
(struct.atomic.rmw.cmpxchg $unshared-i32 0
(local.get 0)
(i32.const 1)
(unreachable)
)
)

;; CHECK: (func $array-rmw-unreachable-lowering (type $19) (param $0 (ref null $array)) (result i32)
;; CHECK-NEXT: (array.atomic.rmw.add $array
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $array-rmw-unreachable-lowering (param (ref null $array)) (result i32)
;; Check that we skip lowering if an operand is unreachable.
(array.atomic.rmw.add $array
(local.get 0)
(i32.const 0)
(unreachable)
)
)

;; CHECK: (func $cmpxchg-unreachable-lowering (type $19) (param $0 (ref null $array)) (result i32)
;; CHECK-NEXT: (array.atomic.rmw.cmpxchg $array
;; CHECK-NEXT: (local.get $0)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (i32.const 1)
;; CHECK-NEXT: (unreachable)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $cmpxchg-unreachable-lowering (param (ref null $array)) (result i32)
(array.atomic.rmw.cmpxchg $array
(local.get 0)
(i32.const 0)
(i32.const 1)
(unreachable)
)
)
)
Loading