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[NFC] Rename Type::isNull to Type::isBottomRef #9288

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Merged
tlively merged 4 commits into from
Oct 21, 2026
Merged

[NFC] Rename Type::isNull to Type::isBottomRef #9288

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3203196
[NFC] Rename Type::is{,Non}NullableRef
tlively Oct 20, 2026
f250db9
[NFC] Rename Type::isNull to Type::isBottomRef
tlively Oct 20, 2026
a4ce38b
Merge remote-tracking branch 'origin/main' into is-bottom-ref-nfc
tlively Oct 20, 2026
5a5979a
use isUninhabitable in more places
tlively Oct 20, 2026
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12 changes: 6 additions & 6 deletions src/analysis/lattices/conetype.h
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Expand Up @@ -47,7 +47,7 @@ struct ConeType {

Element get(Type type) const noexcept {
assert(!type.isTuple());
if (!type.isRef() || type.isExact() || type.isNull() ||
if (!type.isRef() || type.isExact() || type.isBottomRef() ||
type.getHeapType().isMaybeShared(HeapType::i31)) {
return Element{type, 0};
}
Expand All @@ -69,10 +69,10 @@ struct ConeType {
return changed;
}
Index joineeToLub = 0, joinerToLub = 0;
if (!joinee.isBottom() && !joinee.type.isNull()) {
if (!joinee.isBottom() && !joinee.type.isBottomRef()) {
joineeToLub = depthToSuper(joinee, lub);
}
if (!joiner.isBottom() && !joiner.type.isNull()) {
if (!joiner.isBottom() && !joiner.type.isBottomRef()) {
joinerToLub = depthToSuper(joiner, lub);
}
Index newDepth =
Expand Down Expand Up @@ -102,7 +102,7 @@ struct ConeType {
}
Index newDepth;
auto glb = Type::getGreatestLowerBound(meetee.type, meeter.type);
if (glb == Type::unreachable || glb.isNull()) {
if (glb == Type::unreachable || glb.isBottomRef()) {
newDepth = 0;
} else if (HeapType::isSubType(meetee.type.getHeapType(),
meeter.type.getHeapType())) {
Expand Down Expand Up @@ -146,14 +146,14 @@ struct ConeType {
return a.depth < b.depth ? analysis::LESS : analysis::GREATER;
}
if (Type::isSubType(a.type, b.type)) {
if (a.type.isNull()) {
if (a.type.isBottomRef()) {
return analysis::LESS;
}
Index diff = depthToSuper(a, b.type);
return a.depth + diff <= b.depth ? analysis::LESS : analysis::NO_RELATION;
}
if (Type::isSubType(b.type, a.type)) {
if (b.type.isNull()) {
if (b.type.isBottomRef()) {
return analysis::GREATER;
}
Index diff = depthToSuper(b, a.type);
Expand Down
4 changes: 2 additions & 2 deletions src/ir/effects.h
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Expand Up @@ -697,7 +697,7 @@ class EffectAnalyzer {
return true;
}
assert(type.isRef());
if (type.isNull()) {
if (type.isBottomRef()) {
parent.trap = true;
return true;
}
Expand Down Expand Up @@ -1175,7 +1175,7 @@ class EffectAnalyzer {
}

void visitArrayStore(ArrayStore* curr) {
if (curr->ref->type.isNull()) {
if (curr->ref->type.isBottomRef()) {
parent.trap = true;
return;
}
Expand Down
10 changes: 3 additions & 7 deletions src/ir/gc-type-utils.h
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Expand Up @@ -22,7 +22,7 @@
namespace wasm::GCTypeUtils {

inline bool isUninhabitable(Type type) {
return type.isNonNullableRef() && type.getHeapType().isBottom();
return type.isNonNullableRef() && type.isBottomRef();
}

// Helper code to evaluate a reference at compile time and check if it is of a
Expand Down Expand Up @@ -82,9 +82,7 @@ inline EvaluationResult evaluateCastCheck(Type refType, Type castType) {
return Unreachable;
}

auto refHeapType = refType.getHeapType();

if (castType.isNonNullableRef() && refHeapType.isBottom()) {
if (castType.isNonNullableRef() && refType.isBottomRef()) {
// Non-null references to bottom types do not exist, so there's no value
// that could make the cast succeed.
//
Expand All @@ -103,8 +101,6 @@ inline EvaluationResult evaluateCastCheck(Type refType, Type castType) {
return Failure;
}

auto castHeapType = castType.getHeapType();

// Check whether a value of type `a` is known to also have type `b`, assuming
// it is non-null.
auto isHeapSubtype = [](Type a, Type b) {
Expand Down Expand Up @@ -138,7 +134,7 @@ inline EvaluationResult evaluateCastCheck(Type refType, Type castType) {
auto castIsHeapSubType = isHeapSubtype(castType, refType);
bool heapTypesCompatible = refIsHeapSubType || castIsHeapSubType;

if (!heapTypesCompatible || castHeapType.isBottom()) {
if (!heapTypesCompatible || castType.isBottomRef()) {
// If the heap types are incompatible or if it is impossible to have a
// non-null reference to the target heap type, then the only way the cast
// can succeed is if it allows nulls and the input is null.
Expand Down
4 changes: 2 additions & 2 deletions src/ir/possible-contents.cpp
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Expand Up @@ -204,7 +204,7 @@ void PossibleContents::intersect(const PossibleContents& other) {
}
};

if (newType == Type::unreachable || newType.isNull()) {
if (newType == Type::unreachable || newType.isBottomRef()) {
setNoneOrNull();
return;
}
Expand Down Expand Up @@ -3182,7 +3182,7 @@ void Flower::filterPackedDataReads(PossibleContents& contents,
}

// If there is no struct or array to read, no value will ever be returned.
if (ref->type.isNull()) {
if (ref->type.isBottomRef()) {
contents = PossibleContents::none();
return;
}
Expand Down
2 changes: 1 addition & 1 deletion src/ir/properties.h
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Expand Up @@ -537,7 +537,7 @@ inline bool hasUnwritableTypeImmediate(Expression* curr) {
#define DELEGATE_FIELD_IMMEDIATE_TYPED_CHILD(id, field) \
if (curr->cast<id>()->field) { \
auto type = curr->cast<id>()->field->type; \
if (type == Type::unreachable || type.isNull()) { \
if (type == Type::unreachable || type.isBottomRef()) { \
return true; \
} \
}
Expand Down
10 changes: 5 additions & 5 deletions src/ir/struct-utils.h
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Expand Up @@ -222,7 +222,7 @@ struct StructScanner : public WalkerPass<PostWalker<SubType>> {

void visitStructSet(StructSet* curr) {
auto type = curr->ref->type;
if (type == Type::unreachable || type.isNull()) {
if (type == Type::unreachable || type.isBottomRef()) {
return;
}

Expand All @@ -237,7 +237,7 @@ struct StructScanner : public WalkerPass<PostWalker<SubType>> {

void visitStructGet(StructGet* curr) {
auto type = curr->ref->type;
if (type == Type::unreachable || type.isNull()) {
if (type == Type::unreachable || type.isBottomRef()) {
return;
}

Expand All @@ -250,7 +250,7 @@ struct StructScanner : public WalkerPass<PostWalker<SubType>> {

void visitStructWait(StructWait* curr) {
auto type = curr->ref->type;
if (type == Type::unreachable || type.isNull()) {
if (type == Type::unreachable || type.isBottomRef()) {
return;
}

Expand All @@ -263,7 +263,7 @@ struct StructScanner : public WalkerPass<PostWalker<SubType>> {

void visitStructRMW(StructRMW* curr) {
auto type = curr->ref->type;
if (type == Type::unreachable || type.isNull()) {
if (type == Type::unreachable || type.isBottomRef()) {
return;
}

Expand All @@ -286,7 +286,7 @@ struct StructScanner : public WalkerPass<PostWalker<SubType>> {

void visitStructCmpxchg(StructCmpxchg* curr) {
auto type = curr->ref->type;
if (type == Type::unreachable || type.isNull()) {
if (type == Type::unreachable || type.isBottomRef()) {
return;
}

Expand Down
2 changes: 1 addition & 1 deletion src/literal.h
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Expand Up @@ -108,7 +108,7 @@ class Literal {
bool isContinuation() const { return type.isContinuation(); }
bool isString() const { return type.isString(); }

bool isNull() const { return type.isNull(); }
bool isNull() const { return type.isBottomRef(); }

bool isZero() const {
switch (type.getBasic()) {
Expand Down
3 changes: 2 additions & 1 deletion src/passes/DeadArgumentElimination.cpp
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Expand Up @@ -38,6 +38,7 @@
#include <unordered_map>
#include <unordered_set>

#include "ir/gc-type-utils.h"
#include "ir/lubs.h"
#include "ir/return-utils.h"
#include "ir/type-updating.h"
Expand Down Expand Up @@ -551,7 +552,7 @@ struct DAE : public Pass {
// Do this for more complicated uninhabitable types such as non-nullable
// references to structs with non-nullable reference cycles.
bool wasReturnUninhabitable =
func->getResults().isNull() && func->getResults().isNonNullableRef();
GCTypeUtils::isUninhabitable(func->getResults());
func->setResults(Type::none);
// Remove the drops on the calls. Note that we must do this before updating
// returns in ReturnUpdater, as there may be recursive calls of this
Expand Down
11 changes: 6 additions & 5 deletions src/passes/OptimizeInstructions.cpp
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Expand Up @@ -1768,7 +1768,8 @@ struct OptimizeInstructions
// function and the null does not actually flow out. We can only optimize
// here if a null definitely flows out (as only that would cause a trap).
auto flowsOutNull = [&](Expression* child) {
return child->type.isNull() && !effects(child).transfersControlFlow();
return child->type.isBottomRef() &&
!effects(child).transfersControlFlow();
};

if (auto* iff = ref->dynCast<If>()) {
Expand Down Expand Up @@ -1859,7 +1860,7 @@ struct OptimizeInstructions

auto fallthrough = getFallthrough(ref);

if (fallthrough->type.isNull()) {
if (fallthrough->type.isBottomRef()) {
replaceCurrent(
getDroppedChildrenAndAppend(curr, builder.makeUnreachable()));
return true;
Expand Down Expand Up @@ -2497,7 +2498,7 @@ struct OptimizeInstructions
// null, because then we never get around to comparing the
// descriptors. We still need to preserve the trap on null
// descriptors, though.
if (refType.isNull()) {
if (refType.isBottomRef()) {
assert(curr->type.isNullableRef());
if (curr->desc->type.isNullableRef()) {
curr->desc = builder.makeRefAs(RefAsNonNull, curr->desc);
Expand Down Expand Up @@ -2554,7 +2555,7 @@ struct OptimizeInstructions
// because the intermediate expressions might have had side effects or
// we need to check exactness. We can replace the cast with a drop
// followed by a direct return of the value, though.
if (ref->type.isNull()) {
if (ref->type.isBottomRef()) {
// We can materialize the resulting null value directly.
//
// The type must be nullable for us to do that, which it normally
Expand Down Expand Up @@ -2615,7 +2616,7 @@ struct OptimizeInstructions
// In this case, the cast succeeds because the value must be null, so we
// can fall through to handle that case.
assert(Type::isSubType(refType, ref->type));
assert(refType.getHeapType().isBottom());
assert(refType.isBottomRef());
}
[[fallthrough]];
case GCTypeUtils::SuccessOnlyIfNull: {
Expand Down
4 changes: 2 additions & 2 deletions src/passes/Precompute.cpp
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Expand Up @@ -148,7 +148,7 @@ class PrecomputingExpressionRunner
return Flow(NONCONSTANT_FLOW);
}
Flow visitStructGet(StructGet* curr) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isNull()) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isBottomRef()) {
return Flow(NONCONSTANT_FLOW);
}
switch (curr->order) {
Expand Down Expand Up @@ -193,7 +193,7 @@ class PrecomputingExpressionRunner
Flow visitArrayRMW(ArrayRMW* curr) { return Flow(NONCONSTANT_FLOW); }
Flow visitArrayCmpxchg(ArrayCmpxchg* curr) { return Flow(NONCONSTANT_FLOW); }
Flow visitArrayGet(ArrayGet* curr) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isNull()) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isBottomRef()) {
return Flow(NONCONSTANT_FLOW);
}
switch (curr->order) {
Expand Down
4 changes: 2 additions & 2 deletions src/passes/RemoveUnusedBrs.cpp
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Expand Up @@ -922,7 +922,7 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {

switch (curr->op) {
case BrOnNull:
if (refType.isNull()) {
if (refType.isBottomRef()) {
// The branch will definitely be taken.
replaceCurrent(builder.makeSequence(
builder.makeDrop(curr->ref), builder.makeBreak(curr->name)));
Expand All @@ -937,7 +937,7 @@ struct RemoveUnusedBrs : public WalkerPass<PostWalker<RemoveUnusedBrs>> {
}
return;
case BrOnNonNull:
if (refType.isNull()) {
if (refType.isBottomRef()) {
// Definitely not taken.
replaceCurrent(builder.makeDrop(curr->ref));
worked = true;
Expand Down
2 changes: 1 addition & 1 deletion src/passes/RemoveUnusedModuleElements.cpp
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Expand Up @@ -197,7 +197,7 @@ struct Noter : public PostWalker<Noter, UnifiedExpressionVisitor<Noter>> {
}

void visitStructGet(StructGet* curr) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isNull()) {
if (curr->ref->type == Type::unreachable || curr->ref->type.isBottomRef()) {
return;
}
auto type = curr->ref->type.getHeapType();
Expand Down
7 changes: 4 additions & 3 deletions src/passes/TypeRefining.cpp
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Expand Up @@ -262,7 +262,7 @@ struct TypeRefining : public Pass {
auto& infos = finalInfos[{type, Inexact}];
for (Index i = 0; i < fields.size(); i++) {
auto lub = infos[i].getLUB();
if (lub.isRef() && !lub.isCastable() && !lub.isNull()) {
if (lub.isRef() && !lub.isCastable() && !lub.isBottomRef()) {
infos[i] = LUBFinder(fields[i].type);
}
}
Expand Down Expand Up @@ -413,13 +413,14 @@ struct TypeRefining : public Pass {
}

Type newFieldType;
if (!curr->ref->type.isNull()) {
if (!curr->ref->type.isBottomRef()) {
auto oldType = curr->ref->type.getHeapType();
newFieldType =
parent.finalInfos[{oldType, Inexact}][curr->index].getLUB();
}

if (curr->ref->type.isNull() || newFieldType == Type::unreachable ||
if (curr->ref->type.isBottomRef() ||
newFieldType == Type::unreachable ||
!Type::isSubType(newFieldType, curr->type)) {
// This get will trap, or cannot be reached: either the ref is null,
// or the field is never written any contents, or the contents we see
Expand Down
8 changes: 5 additions & 3 deletions src/tools/fuzzing/heap-types.cpp
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Expand Up @@ -1027,7 +1027,7 @@ void Inhabitator::markBottomRefsNullable() {
auto children = type.getTypeChildren();
for (size_t i = 0; i < children.size(); ++i) {
auto child = children[i];
if (child.isNonNullableRef() && child.getHeapType().isBottom()) {
if (child.isNonNullableRef() && child.isBottomRef()) {

@gemini-code-assist gemini-code-assist Bot Oct 20, 2026

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medium

We can simplify this check by using the helper function GCTypeUtils::isUninhabitable(child) here as well, which makes the code more expressive.

Suggested change
if (child.isNonNullableRef() && child.isBottomRef()) {
if (GCTypeUtils::isUninhabitable(child)) {

markNullable({type, i});
}
}
Expand Down Expand Up @@ -1400,9 +1400,11 @@ bool isUninhabitable(HeapType type,
bool isUninhabitable(Type type,
std::unordered_set<HeapType>& visited,
std::unordered_set<HeapType>& visiting) {
if (GCTypeUtils::isUninhabitable(type)) {
return true;
}
if (type.isNonNullableRef()) {
if (type.getHeapType().isBottom() ||
type.getHeapType().isMaybeShared(HeapType::ext)) {
if (type.getHeapType().isMaybeShared(HeapType::ext)) {
return true;
}
return isUninhabitable(type.getHeapType(), visited, visiting);
Expand Down
4 changes: 1 addition & 3 deletions src/wasm-type.h
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Expand Up @@ -412,9 +412,7 @@ class Type {
bool isFunction() const { return isRef() && getHeapType().isFunction(); }
bool isSignature() const { return isRef() && getHeapType().isSignature(); }
bool isData() const { return isRef() && getHeapType().isData(); }

// Whether this type is only inhabited by null values.
bool isNull() const { return isRef() && getHeapType().isBottom(); }
bool isBottomRef() const { return isRef() && getHeapType().isBottom(); }
bool isStruct() const { return isRef() && getHeapType().isStruct(); }
bool isArray() const { return isRef() && getHeapType().isArray(); }
bool isExn() const { return isRef() && getHeapType().isExn(); }
Expand Down
7 changes: 3 additions & 4 deletions src/wasm/literal.cpp
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Expand Up @@ -52,7 +52,7 @@ Literal::Literal(Type type) : type(type) {
}
}

if (type.isNull()) {
if (type.isBottomRef()) {
assert(type.isNullableRef() && !type.isExact());
new (&gcData) std::shared_ptr<GCData>();
return;
Expand Down Expand Up @@ -503,8 +503,7 @@ bool Literal::operator==(const Literal& other) const {
break;
}
} else if (type.isRef()) {
assert(type.isRef());
if (type.isNull()) {
if (type.isBottomRef()) {
return true;
}
if (type.isFunction()) {
Expand Down Expand Up @@ -567,7 +566,7 @@ bool Literal::operator<(const Literal& other) const {
}

assert(type.isRef());
if (type.isNull()) {
if (type.isBottomRef()) {
// All nulls are equal, and hence not <
return false;
}
Expand Down
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