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Use fewer bits for BasicHeapType #7404

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Merged
tlively merged 5 commits into from
Mar 26, 2025
Merged

Use fewer bits for BasicHeapType #7404

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0f46cad
Revert exact reference types
tlively Mar 26, 2025
a475c44
Use fewer bits for BasicHeapType
tlively Mar 26, 2025
35aa881
Merge branch 'main' into remove-exact-references
tlively Mar 26, 2025
91155ad
Merge branch 'remove-exact-references' into no-exact-reftype-repr
tlively Mar 26, 2025
5e343e0
Merge branch 'main' into no-exact-reftype-repr
tlively Mar 26, 2025
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14 changes: 6 additions & 8 deletions src/wasm-type.h
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Original file line number Diff line number Diff line change
Expand Up @@ -95,13 +95,13 @@ class HeapType {
// should also be passed by value.
uintptr_t id;

static constexpr int TypeBits = 3;
static constexpr int TypeBits = 2;
static constexpr int UsedBits = TypeBits + 1;
static constexpr int SharedMask = 1 << TypeBits;

public:
// Bits 0-2 are used by the Type representation, so need to be left free.
// Bit 3 determines whether the basic heap type is shared (1) or unshared (0).
// Bits 0-1 are used by the Type representation, so need to be left free.
// Bit 2 determines whether the basic heap type is shared (1) or unshared (0).
enum BasicHeapType : uint32_t {
ext = 1 << UsedBits,
func = 2 << UsedBits,
Expand Down Expand Up @@ -278,7 +278,7 @@ class Type {
// bit 0 set. When that bit is masked off, they are pointers to the underlying
// vectors of types. Otherwise, the type is a reference type, and is
// represented as a heap type with bit 1 set iff the reference type is
// nullable and bit 2 set iff the reference type is exact.
// nullable.
//
// Since `Type` is really just a single integer, it should be passed by value.
// This is a uintptr_t rather than a TypeID (uint64_t) to save memory on
Expand All @@ -287,7 +287,6 @@ class Type {

static constexpr int TupleMask = 1 << 0;
static constexpr int NullMask = 1 << 1;
static constexpr int ExactMask = 1 << 2;

public:
enum BasicType : uint32_t {
Expand Down Expand Up @@ -320,8 +319,7 @@ class Type {
// Signature, Struct or Array via implicit conversion to HeapType.
Type(HeapType heapType, Nullability nullable)
: Type(heapType.getID() | (nullable == Nullable ? NullMask : 0)) {
assert(heapType.isBasic() ||
!(heapType.getID() & (TupleMask | NullMask | ExactMask)));
assert(heapType.isBasic() || !(heapType.getID() & (TupleMask | NullMask)));
}

// Predicates
Expand Down Expand Up @@ -372,7 +370,7 @@ class Type {
bool isNonNullable() const { return isRef() && !(id & NullMask); }
HeapType getHeapType() const {
assert(isRef());
return HeapType(id & ~(NullMask | ExactMask));
return HeapType(id & ~NullMask);
}

bool isFunction() const { return isRef() && getHeapType().isFunction(); }
Expand Down
22 changes: 11 additions & 11 deletions test/example/c-api-kitchen-sink.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -20,17 +20,17 @@ BinaryenTypeAuto: -1
BinaryenPackedTypeNotPacked: 0
BinaryenPackedTypeInt8: 1
BinaryenPackedTypeInt16: 2
BinaryenHeapTypeExt: 16
BinaryenHeapTypeFunc: 32
BinaryenHeapTypeAny: 64
BinaryenHeapTypeEq: 80
BinaryenHeapTypeI31: 96
BinaryenHeapTypeStruct: 112
BinaryenHeapTypeArray: 128
BinaryenHeapTypeString: 160
BinaryenHeapTypeNone: 176
BinaryenHeapTypeNoext: 192
BinaryenHeapTypeNofunc: 208
BinaryenHeapTypeExt: 8
BinaryenHeapTypeFunc: 16
BinaryenHeapTypeAny: 32
BinaryenHeapTypeEq: 40
BinaryenHeapTypeI31: 48
BinaryenHeapTypeStruct: 56
BinaryenHeapTypeArray: 64
BinaryenHeapTypeString: 80
BinaryenHeapTypeNone: 88
BinaryenHeapTypeNoext: 96
BinaryenHeapTypeNofunc: 104
BinaryenFeatureMVP: 0
BinaryenFeatureAtomics: 1
BinaryenFeatureBulkMemory: 16
Expand Down