src/tint/lang/msl/writer/ast_raise/quad_swap.h

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#ifndef SRC_TINT_LANG_MSL_WRITER_AST_RAISE_QUAD_SWAP_H_
#define SRC_TINT_LANG_MSL_WRITER_AST_RAISE_QUAD_SWAP_H_

#include <string>

#include "src/tint/lang/wgsl/ast/internal_attribute.h"
#include "src/tint/lang/wgsl/ast/transform/transform.h"

namespace tint::msl::writer {

/// QuadSwap is a transform that replaces calls to `quadSwap{X, Y, Diagonal}()` with an
/// implementation that uses MSL's `quad_shuffle()` using the following mapping:
/// +------------------+------------------------------------------------------------------+
/// |       WGSL       |                               MSL                                |
/// +------------------+------------------------------------------------------------------+
/// | quadSwapX        | quad_shuffle with quad_lane_id=thread_index_in_quad_group ^ 0b1  |
/// | quadSwapY        | quad_shuffle with quad_lane_id=thread_index_in_quad_group ^ 0b10 |
/// | quadSwapDiagonal | quad_shuffle with quad_lane_id=thread_index_in_quad_group ^ 0b11 |
/// +------------------+------------------------------------------------------------------+
///
/// @note Depends on the following transforms to have been run first:
/// * CanonicalizeEntryPointIO
class QuadSwap final : public Castable<QuadSwap, ast::transform::Transform> {
  public:
    /// Constructor
    QuadSwap();

    /// Destructor
    ~QuadSwap() override;

    /// @copydoc ast::transform::Transform::Apply
    ApplyResult Apply(const Program& program,
                      const ast::transform::DataMap& inputs,
                      ast::transform::DataMap& outputs) const override;

    /// QuadShuffle is an InternalAttribute that is used to decorate a stub function so
    /// that the MSL backend transforms this into calls to the `quad_shuffle` function.
    class QuadShuffle final : public Castable<QuadShuffle, ast::InternalAttribute> {
      public:
        /// Constructor
        /// @param pid the identifier of the program that owns this node
        /// @param nid the unique node identifier
        QuadShuffle(GenerationID pid, ast::NodeID nid) : Base(pid, nid, Empty) {}

        /// Destructor
        ~QuadShuffle() override;

        /// @copydoc ast::InternalAttribute::InternalName
        std::string InternalName() const override { return "quad_shuffle"; }

        /// Performs a deep clone of this object using the program::CloneContext `ctx`.
        /// @param ctx the clone context
        /// @return the newly cloned object
        const QuadShuffle* Clone(ast::CloneContext& ctx) const override;
    };

    /// ThreadIndexInQuadgroup is an InternalAttribute that is used to decorate an entrypoint
    /// parameter so that the MSL backend transforms this into a `[[thread_index_in_quadgroup]]`
    /// attribute.
    class ThreadIndexInQuadgroup final
        : public Castable<ThreadIndexInQuadgroup, ast::InternalAttribute> {
      public:
        /// Constructor
        /// @param pid the identifier of the program that owns this node
        /// @param nid the unique node identifier
        ThreadIndexInQuadgroup(GenerationID pid, ast::NodeID nid) : Base(pid, nid, Empty) {}

        /// Destructor
        ~ThreadIndexInQuadgroup() override;

        /// @copydoc ast::InternalAttribute::InternalName
        std::string InternalName() const override { return "thread_index_in_quadgroup"; }

        /// Performs a deep clone of this object using the program::CloneContext `ctx`.
        /// @param ctx the clone context
        /// @return the newly cloned object
        const ThreadIndexInQuadgroup* Clone(ast::CloneContext& ctx) const override;
    };

  private:
    struct State;
};

}  // namespace tint::msl::writer

#endif  // SRC_TINT_LANG_MSL_WRITER_AST_RAISE_QUAD_SWAP_H_