Skip to content

More ArrayCmpxchg expected opts in Heap2Local #8567

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 2 commits into from
Apr 2, 2026
Merged

More ArrayCmpxchg expected opts in Heap2Local #8567

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
9a370c0
More ArrayCmpxchg expected opts in Heap2Local
tlively Apr 2, 2026
8c3bbec
address review comments
tlively Apr 2, 2026
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
59 changes: 27 additions & 32 deletions src/passes/Heap2Local.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -461,40 +461,29 @@ struct EscapeAnalyzer {
}
}
void visitArraySet(ArraySet* curr) {
if (!curr->index->is<Const>()) {
// Array operations on nonconstant indexes do not escape in the normal
// sense, but they do escape from our being able to analyze them, so
// stop as soon as we see one.
return;
}

// As StructGet.
if (curr->ref == child) {
// Arrays flowing into array operations on nonconstant indexes do not
// escape in the normal sense, but they do escape from our being able to
// analyze them, so stop as soon as we see one.
if (child == curr->ref && curr->index->is<Const>()) {
escapes = false;
fullyConsumes = true;
}
}
void visitArrayGet(ArrayGet* curr) {
if (!curr->index->is<Const>()) {
return;
if (child == curr->ref && curr->index->is<Const>()) {
escapes = false;
fullyConsumes = true;
}
escapes = false;
fullyConsumes = true;
}
void visitArrayRMW(ArrayRMW* curr) {
if (!curr->index->is<Const>()) {
return;
}
if (curr->ref == child) {
if (child == curr->ref && curr->index->is<Const>()) {
escapes = false;
fullyConsumes = true;
}
}
void visitArrayCmpxchg(ArrayCmpxchg* curr) {
if (!curr->index->is<Const>()) {
return;
}
if (curr->ref == child || curr->expected == child) {
if (child == curr->expected ||
Copy link
Copy Markdown
Member

@kripken kripken Apr 2, 2026

Choose a reason for hiding this comment

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

Worth a comment here I think, as in the PR description.

(child == curr->ref && curr->index->is<Const>())) {
escapes = false;
fullyConsumes = true;
}
Expand Down Expand Up @@ -1233,9 +1222,15 @@ struct Struct2Local : PostWalker<Struct2Local> {
auto refScratch = builder.addVar(func, refType);
auto* setRefScratch = builder.makeLocalSet(refScratch, curr->ref);
auto* getRefScratch = builder.makeLocalGet(refScratch, refType);

auto indexScratch = builder.addVar(func, Type::i32);
auto* setIndexScratch = builder.makeLocalSet(indexScratch, curr->index);
auto* getIndexScratch = builder.makeLocalGet(indexScratch, Type::i32);

auto* arrayGet = builder.makeArrayGet(
getRefScratch, curr->index, curr->order, curr->type);
getRefScratch, getIndexScratch, curr->order, curr->type);
auto* block = builder.makeBlock({setRefScratch,
setIndexScratch,
builder.makeDrop(curr->expected),
builder.makeDrop(curr->replacement),
arrayGet});
Expand Down Expand Up @@ -1467,19 +1462,19 @@ struct Array2Struct : PostWalker<Array2Struct> {
return;
}

auto index = getIndex(curr->index);
if (index >= numFields) {
replaceCurrent(builder.makeBlock({builder.makeDrop(curr->ref),
builder.makeDrop(curr->expected),
builder.makeDrop(curr->replacement),
builder.makeUnreachable()}));
refinalize = true;
return;
}

// The allocation might flow into `ref` or `expected`, but not
// `replacement`, because then it would be considered to have escaped.
if (analyzer.getInteraction(curr->ref) == ParentChildInteraction::Flows) {
auto index = getIndex(curr->index);
if (index >= numFields) {
replaceCurrent(builder.makeBlock({builder.makeDrop(curr->ref),
builder.makeDrop(curr->expected),
builder.makeDrop(curr->replacement),
builder.makeUnreachable()}));
refinalize = true;
return;
}

// The accessed array is being optimzied. Convert the ArrayCmpxchg into a
Copy link
Copy Markdown
Member

@kripken kripken Apr 2, 2026

Choose a reason for hiding this comment

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

Suggested change
// The accessed array is being optimzied. Convert the ArrayCmpxchg into a
// The accessed array is being optimized. Convert the ArrayCmpxchg into a

(pre-existing, but while we are here)

// StructCmpxchg.
replaceCurrent(builder.makeStructCmpxchg(
Expand Down
64 changes: 63 additions & 1 deletion test/lit/passes/heap2local-rmw.wast
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1465,11 +1465,15 @@
;; CHECK: (func $array-cmpxchg-expected (type $1) (param $array (ref $array))
;; CHECK-NEXT: (local $1 eqref)
;; CHECK-NEXT: (local $2 (ref null $array))
;; CHECK-NEXT: (local $3 i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result eqref)
;; CHECK-NEXT: (local.set $2
;; CHECK-NEXT: (local.get $array)
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $3
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result nullref)
;; CHECK-NEXT: (local.set $1
Expand All @@ -1483,7 +1487,7 @@
;; CHECK-NEXT: )
;; CHECK-NEXT: (array.atomic.get $array
;; CHECK-NEXT: (local.get $2)
;; CHECK-NEXT: (i32.const 0)
;; CHECK-NEXT: (local.get $3)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
Expand All @@ -1504,3 +1508,61 @@
)
)
)

(module
;; CHECK: (type $array (array (mut eqref)))
(type $array (array (mut eqref)))
;; CHECK: (type $1 (func (result i32)))

;; CHECK: (type $2 (func (result eqref)))

;; CHECK: (type $3 (func (param (ref $array))))

;; CHECK: (import "" "" (func $effect-i32 (type $1) (result i32)))
(import "" "" (func $effect-i32 (result i32)))
;; CHECK: (import "" "" (func $effect-eq (type $2) (result eqref)))
(import "" "" (func $effect-eq (result eqref)))

;; CHECK: (func $array-cmpxchg-expected-index-effect (type $3) (param $array (ref $array))
;; CHECK-NEXT: (local $1 eqref)
;; CHECK-NEXT: (local $2 (ref null $array))
;; CHECK-NEXT: (local $3 i32)
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result eqref)
;; CHECK-NEXT: (local.set $2
;; CHECK-NEXT: (local.get $array)
;; CHECK-NEXT: )
;; CHECK-NEXT: (local.set $3
;; CHECK-NEXT: (call $effect-i32)
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (block (result nullref)
;; CHECK-NEXT: (local.set $1
;; CHECK-NEXT: (ref.null none)
;; CHECK-NEXT: )
;; CHECK-NEXT: (ref.null none)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: (drop
;; CHECK-NEXT: (call $effect-eq)
;; CHECK-NEXT: )
;; CHECK-NEXT: (array.atomic.get $array
;; CHECK-NEXT: (local.get $2)
;; CHECK-NEXT: (local.get $3)
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
;; CHECK-NEXT: )
(func $array-cmpxchg-expected-index-effect (param $array (ref $array))
(drop
;; The index is non-constant, but we can still optimize the expected
;; field. We must preserve the index and the order of its effects.
(array.atomic.rmw.cmpxchg $array
(local.get $array)
(call $effect-i32)
(array.new_default $array (i32.const 1))
(call $effect-eq)
)
Copy link
Copy Markdown
Member

@kripken kripken Apr 2, 2026

Choose a reason for hiding this comment

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

Is there a test for array.atomic.rmw.cmpxchg where we optimize the expected field but the index is out of bounds?

Copy link
Copy Markdown
Member Author

@tlively tlively Apr 2, 2026

Choose a reason for hiding this comment

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

The output will look the same, but I will add a test where the index is an OOB constant.

)
)
)
Loading