src/tint/transform/std140.h

// Copyright 2022 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_TRANSFORM_STD140_H_
#define SRC_TINT_TRANSFORM_STD140_H_

#include "src/tint/transform/transform.h"

namespace tint::transform {

/// Std140 is a transform that forks structures used in the uniform storage class that contain
/// `matNx2<f32>` matrices into `N`x`vec2<f32>` column vectors. Structure types that transitively
/// use these forked structures as members are also forked. `var<uniform>` variables will use these
/// forked structures, and expressions loading from these variables will do appropriate conversions
/// to the regular WGSL types. As `matNx2<f32>` matrices are the only type that violate
/// std140-layout, this transformation is sufficient to have any WGSL structure be std140-layout
/// conformant.
///
/// @note This transform requires the PromoteSideEffectsToDecl transform to have been run first.
class Std140 final : public Castable<Std140, Transform> {
  public:
    /// Constructor
    Std140();
    /// Destructor
    ~Std140() override;

    /// @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;

  private:
    struct State;

    /// 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 tint::transform

#endif  // SRC_TINT_TRANSFORM_STD140_H_