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// Copyright 2021 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_TINT_SEM_ARRAY_H_
#define SRC_TINT_SEM_ARRAY_H_
#include <stdint.h>
#include <optional>
#include <string>
#include <variant>
#include "src/tint/sem/node.h"
#include "src/tint/sem/type.h"
#include "src/tint/utils/compiler_macros.h"
// Forward declarations
namespace tint::sem {
class GlobalVariable;
} // namespace tint::sem
namespace tint::sem {
/// The variant of an ArrayCount when the array is a const-expression.
/// Example:
/// ```
/// const N = 123;
/// type arr = array<i32, N>
/// ```
struct ConstantArrayCount {
/// The array count constant-expression value.
uint32_t value;
};
/// The variant of an ArrayCount when the count is a named override variable.
/// Example:
/// ```
/// override N : i32;
/// type arr = array<i32, N>
/// ```
struct OverrideArrayCount {
/// The `override` variable.
const GlobalVariable* variable;
};
/// The variant of an ArrayCount when the array is is runtime-sized.
/// Example:
/// ```
/// type arr = array<i32>
/// ```
struct RuntimeArrayCount {};
/// An array count is either a constant-expression value, an override identifier, or runtime-sized.
using ArrayCount = std::variant<ConstantArrayCount, OverrideArrayCount, RuntimeArrayCount>;
/// Equality operator
/// @param a the LHS ConstantArrayCount
/// @param b the RHS ConstantArrayCount
/// @returns true if @p a is equal to @p b
inline bool operator==(const ConstantArrayCount& a, const ConstantArrayCount& b) {
return a.value == b.value;
}
/// Equality operator
/// @param a the LHS OverrideArrayCount
/// @param b the RHS OverrideArrayCount
/// @returns true if @p a is equal to @p b
inline bool operator==(const OverrideArrayCount& a, const OverrideArrayCount& b) {
return a.variable == b.variable;
}
/// Equality operator
/// @returns true
inline bool operator==(const RuntimeArrayCount&, const RuntimeArrayCount&) {
return true;
}
/// Equality operator
/// @param a the LHS ArrayCount
/// @param b the RHS count
/// @returns true if @p a is equal to @p b
template <typename T,
typename = std::enable_if_t<std::is_same_v<T, ConstantArrayCount> ||
std::is_same_v<T, OverrideArrayCount> ||
std::is_same_v<T, RuntimeArrayCount>>>
inline bool operator==(const ArrayCount& a, const T& b) {
TINT_BEGIN_DISABLE_WARNING(UNREACHABLE_CODE);
return std::visit(
[&](auto count) {
if constexpr (std::is_same_v<std::decay_t<decltype(count)>, T>) {
return count == b;
}
return false;
},
a);
TINT_END_DISABLE_WARNING(UNREACHABLE_CODE);
}
/// Array holds the semantic information for Array nodes.
class Array final : public Castable<Array, Type> {
public:
/// An error message string stating that the array count was expected to be a constant
/// expression. Used by multiple writers and transforms.
static const char* const kErrExpectedConstantCount;
/// Constructor
/// @param element the array element type
/// @param count the number of elements in the array.
/// @param align the byte alignment of the array
/// @param size the byte size of the array. The size will be 0 if the array element count is
/// pipeline overridable.
/// @param stride the number of bytes from the start of one element of the
/// array to the start of the next element
/// @param implicit_stride the number of bytes from the start of one element
/// of the array to the start of the next element, if there was no `@stride`
/// attribute applied.
Array(Type const* element,
ArrayCount count,
uint32_t align,
uint32_t size,
uint32_t stride,
uint32_t implicit_stride);
/// @returns a hash of the type.
size_t Hash() const override;
/// @param other the other type to compare against
/// @returns true if the this type is equal to the given type
bool Equals(const Type& other) const override;
/// @return the array element type
Type const* ElemType() const { return element_; }
/// @returns the number of elements in the array.
const ArrayCount& Count() const { return count_; }
/// @returns the array count if the count is a const-expression, otherwise returns nullopt.
inline std::optional<uint32_t> ConstantCount() const {
if (auto* count = std::get_if<ConstantArrayCount>(&count_)) {
return count->value;
}
return std::nullopt;
}
/// @returns the byte alignment of the array
/// @note this may differ from the alignment of a structure member of this
/// array type, if the member is annotated with the `@align(n)` attribute.
uint32_t Align() const override;
/// @returns the byte size of the array
/// @note this may differ from the size of a structure member of this array
/// type, if the member is annotated with the `@size(n)` attribute.
uint32_t Size() const override;
/// @returns the number of bytes from the start of one element of the
/// array to the start of the next element
uint32_t Stride() const { return stride_; }
/// @returns the number of bytes from the start of one element of the
/// array to the start of the next element, if there was no `@stride`
/// attribute applied
uint32_t ImplicitStride() const { return implicit_stride_; }
/// @returns true if the value returned by Stride() matches the element's
/// natural stride
bool IsStrideImplicit() const { return stride_ == implicit_stride_; }
/// @returns true if this array is sized using an const-expression
bool IsConstantSized() const { return std::holds_alternative<ConstantArrayCount>(count_); }
/// @returns true if this array is sized using an override variable
bool IsOverrideSized() const { return std::holds_alternative<OverrideArrayCount>(count_); }
/// @returns true if this array is runtime sized
bool IsRuntimeSized() const { return std::holds_alternative<RuntimeArrayCount>(count_); }
/// @param symbols the program's symbol table
/// @returns the name for this type that closely resembles how it would be
/// declared in WGSL.
std::string FriendlyName(const SymbolTable& symbols) const override;
private:
Type const* const element_;
const ArrayCount count_;
const uint32_t align_;
const uint32_t size_;
const uint32_t stride_;
const uint32_t implicit_stride_;
};
} // namespace tint::sem
namespace std {
/// Custom std::hash specialization for tint::sem::ConstantArrayCount.
template <>
class hash<tint::sem::ConstantArrayCount> {
public:
/// @param count the count to hash
/// @return the hash value
inline std::size_t operator()(const tint::sem::ConstantArrayCount& count) const {
return std::hash<decltype(count.value)>()(count.value);
}
};
/// Custom std::hash specialization for tint::sem::OverrideArrayCount.
template <>
class hash<tint::sem::OverrideArrayCount> {
public:
/// @param count the count to hash
/// @return the hash value
inline std::size_t operator()(const tint::sem::OverrideArrayCount& count) const {
return std::hash<decltype(count.variable)>()(count.variable);
}
};
/// Custom std::hash specialization for tint::sem::RuntimeArrayCount.
template <>
class hash<tint::sem::RuntimeArrayCount> {
public:
/// @return the hash value
inline std::size_t operator()(const tint::sem::RuntimeArrayCount&) const { return 42; }
};
} // namespace std
#endif // SRC_TINT_SEM_ARRAY_H_