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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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <unordered_map>
#include <unordered_set>
#include "src/sem/binding_point.h"
#include "src/transform/transform.h"
namespace tint {
// Forward declarations
class CloneContext;
namespace transform {
/// ArrayLengthFromUniform is a transform that implements calls to arrayLength()
/// by calculating the length from the total size of the storage buffer, which
/// is received via a uniform buffer.
/// The generated uniform buffer will have the form:
/// ```
/// struct buffer_size_struct {
/// buffer_size : array<u32, 8>;
/// };
/// @group(0) @binding(30)
/// var<uniform> buffer_size_ubo : buffer_size_struct;
/// ```
/// The binding group and number used for this uniform buffer is provided via
/// the `Config` transform input. The `Config` struct also defines the mapping
/// from a storage buffer's `BindingPoint` to the array index that will be used
/// to get the size of that buffer.
/// This transform assumes that the `SimplifyPointers`
/// transforms have been run before it so that arguments to the arrayLength
/// builtin always have the form `&resource.array`.
/// @note Depends on the following transforms to have been run first:
/// * SimplifyPointers
class ArrayLengthFromUniform
: public Castable<ArrayLengthFromUniform, Transform> {
/// Constructor
/// Destructor
~ArrayLengthFromUniform() override;
/// Configuration options for the ArrayLengthFromUniform transform.
struct Config : public Castable<Data, transform::Data> {
/// Constructor
/// @param ubo_bp the binding point to use for the generated uniform buffer.
explicit Config(sem::BindingPoint ubo_bp);
/// Copy constructor
Config(const Config&);
/// Copy assignment
/// @return this Config
Config& operator=(const Config&);
/// Destructor
~Config() override;
/// The binding point to use for the generated uniform buffer.
sem::BindingPoint ubo_binding;
/// The mapping from binding point to the index for the buffer size lookup.
std::unordered_map<sem::BindingPoint, uint32_t> bindpoint_to_size_index;
/// Information produced about what the transform did.
/// If there were no calls to the arrayLength() intrinsic, then no Result will
/// be emitted.
struct Result : public Castable<Result, transform::Data> {
/// Constructor
/// @param used_size_indices Indices into the UBO that are statically used.
explicit Result(std::unordered_set<uint32_t> used_size_indices);
/// Copy constructor
Result(const Result&);
/// Destructor
~Result() override;
/// Indices into the UBO that are statically used.
const std::unordered_set<uint32_t> used_size_indices;
/// @param program the program to inspect
/// @param data optional extra transform-specific input data
/// @returns true if this transform should be run for the given program
bool ShouldRun(const Program* program,
const DataMap& data = {}) const override;
/// Runs the transform using the CloneContext built for transforming a
/// program. Run() is responsible for calling Clone() on the CloneContext.
/// @param ctx the CloneContext primed with the input program and
/// ProgramBuilder
/// @param inputs optional extra transform-specific input data
/// @param outputs optional extra transform-specific output data
void Run(CloneContext& ctx,
const DataMap& inputs,
DataMap& outputs) const override;
} // namespace transform
} // namespace tint