src/tint/lang/core/ir/transform/array_length_from_uniform.h

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#ifndef SRC_TINT_LANG_CORE_IR_TRANSFORM_ARRAY_LENGTH_FROM_UNIFORM_H_
#define SRC_TINT_LANG_CORE_IR_TRANSFORM_ARRAY_LENGTH_FROM_UNIFORM_H_

#include <unordered_map>
#include "src/tint/lang/core/ir/validator.h"

#include "src/tint/api/common/binding_point.h"
#include "src/tint/utils/result.h"

// Forward declarations.
namespace tint::core::ir {
class Module;
}

namespace tint::core::ir::transform {

/// The capabilities that the transform can support.
const Capabilities kArrayLengthFromUniformCapabilities{Capability::kAllowDuplicateBindings};

/// The result of running the ArrayLengthFromUniform transform.
struct ArrayLengthFromUniformResult {
    /// `true` if the transformed module needs the storage buffer sizes UBO.
    bool needs_storage_buffer_sizes = false;
};

/// ArrayLengthFromUniform is a transform that replaces calls to the arrayLength() builtin by
/// calculating the array length from the total size of the storage buffer, which is received via a
/// uniform buffer.
///
/// The generated uniform buffer will have the form:
/// ```
/// @group(0) @binding(30)
/// var<uniform> buffer_size_ubo : array<vec4<u32>, 8>;
/// ```
/// The binding group and number used for this uniform buffer is provided via the transform config.
/// The transform config also defines the mapping from a storage buffer's `BindingPoint` to the
/// element index that will be used to get the size of that buffer.
///
/// @param module the module to transform
/// @param ubo_binding the binding point to use for the uniform buffer
/// @param bindpoint_to_size_index the map from binding point to an index which holds the size
/// @returns the transform result or failure
Result<ArrayLengthFromUniformResult> ArrayLengthFromUniform(
    Module& module,
    BindingPoint ubo_binding,
    const std::unordered_map<BindingPoint, uint32_t>& bindpoint_to_size_index);

}  // namespace tint::core::ir::transform

#endif  // SRC_TINT_LANG_CORE_IR_TRANSFORM_ARRAY_LENGTH_FROM_UNIFORM_H_