================
@@ -3173,41 +3174,46 @@ class ArrayType : public Type, public
llvm::FoldingSetNode {
return T->getTypeClass() == ConstantArray ||
T->getTypeClass() == VariableArray ||
T->getTypeClass() == IncompleteArray ||
- T->getTypeClass() == DependentSizedArray;
+ T->getTypeClass() == DependentSizedArray ||
+ T->getTypeClass() == ArrayParameter;
}
};
/// Represents the canonical version of C arrays with a specified constant
size.
/// For example, the canonical type for 'int A[4 + 4*100]' is a
/// ConstantArrayType where the element type is 'int' and the size is 404.
-class ConstantArrayType final
- : public ArrayType,
- private llvm::TrailingObjects<ConstantArrayType, const Expr *> {
----------------
zygoloid wrote:
The size expression is usually not part of a constant array type. Normally, all
we want as part of the type node is the bound, and the size expression if
needed can be found on the `ArrayTypeLoc`. The rare special case being handled
here is that if the array bound is instantiation-dependent but not dependent,
then we need to preserve the expression in the type (not just in the `TypeLoc`)
because it affects (for example) whether two template declarations involving
such a type are considered to declare the same template. Because this is a very
rare case, and `ConstantArrayType`s can be relatively common (eg, as the types
of string literals), it seemed preferable to not store the `Expr*` if it's not
needed, but in absolute terms it's probably a minor difference in memory usage,
so it's probably fine to remove this optimization.
If we want to keep the optimization, perhaps we could replace the `Size` and
`SizeExpr` fields with a pointer union that can hold either a <= 63-bit array
bound (the common case) or a pointer to a slab-allocated pair of `APInt` and
`const Expr*` (in the case where the bound doesn't fit in 63 bits or the size
expression is instantiation-dependent).
https://github.com/llvm/llvm-project/pull/79382
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