src/transform/num_workgroups_from_uniform.h

// 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_TRANSFORM_NUM_WORKGROUPS_FROM_UNIFORM_H_
#define SRC_TRANSFORM_NUM_WORKGROUPS_FROM_UNIFORM_H_

#include "src/sem/binding_point.h"
#include "src/transform/transform.h"

namespace tint {

// Forward declarations
class CloneContext;

namespace transform {

/// NumWorkgroupsFromUniform is a transform that implements the `num_workgroups`
/// builtin by loading it from a uniform buffer.
///
/// The generated uniform buffer will have the form:
/// ```
/// struct num_workgroups_struct {
///  num_workgroups : vec3<u32>;
/// };
///
/// @group(0) @binding(0)
/// var<uniform> num_workgroups_ubo : num_workgroups_struct;
/// ```
/// The binding group and number used for this uniform buffer is provided via
/// the `Config` transform input.
///
/// @note Depends on the following transforms to have been run first:
/// * CanonicalizeEntryPointIO
class NumWorkgroupsFromUniform
    : public Castable<NumWorkgroupsFromUniform, Transform> {
 public:
  /// Constructor
  NumWorkgroupsFromUniform();
  /// Destructor
  ~NumWorkgroupsFromUniform() override;

  /// Configuration options for the NumWorkgroupsFromUniform 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&);

    /// Destructor
    ~Config() override;

    /// The binding point to use for the generated uniform buffer.
    sem::BindingPoint ubo_binding;
  };

  /// @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;

 protected:
  /// 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

#endif  // SRC_TRANSFORM_NUM_WORKGROUPS_FROM_UNIFORM_H_