src/tint/lang/glsl/writer/common/option_helpers.cc

// Copyright 2024 The Dawn & Tint Authors
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#include "src/tint/lang/glsl/writer/common/option_helpers.h"

#include <iostream>
#include <utility>

#include "src/tint/utils/containers/hashmap.h"

namespace tint::glsl::writer {

Result<SuccessType> ValidateBindingOptions(const Options& options) {
    diag::List diagnostics;

    tint::Hashmap<tint::BindingPoint, binding::BindingInfo, 8> seen_wgsl_bindings{};
    tint::Hashmap<binding::BindingInfo, tint::BindingPoint, 8> seen_glsl_bindings{};

    // Both wgsl_seen and glsl_seen check to see if the pair of [src, dst] are unique. If
    // we have multiple entries that map the same [src, dst] pair, that's fine. We treat it as valid
    // as it's possible for multiple entry points to use the remapper at the same time. If the pair
    // doesn't match, then we report an error about a duplicate binding point.
    auto wgsl_seen = [&diagnostics, &seen_wgsl_bindings](const tint::BindingPoint& src,
                                                         const binding::BindingInfo& dst) -> bool {
        if (auto binding = seen_wgsl_bindings.Get(src)) {
            if (*binding != dst) {
                diagnostics.AddError(Source{}) << "found duplicate WGSL binding point: " << src;
                return true;
            }
        }
        seen_wgsl_bindings.Add(src, dst);
        return false;
    };

    auto glsl_seen = [&diagnostics, &seen_glsl_bindings](const binding::BindingInfo& src,
                                                         const tint::BindingPoint& dst) -> bool {
        if (auto binding = seen_glsl_bindings.Get(src)) {
            if (*binding != dst) {
                diagnostics.AddError(Source{})
                    << "found duplicate GLSL binding point: [binding: " << src.binding << "]";
                return true;
            }
        }
        seen_glsl_bindings.Add(src, dst);
        return false;
    };

    auto valid = [&wgsl_seen, &glsl_seen](const auto& hsh) -> bool {
        for (const auto& it : hsh) {
            const auto& src_binding = it.first;
            const auto& dst_binding = it.second;

            if (wgsl_seen(src_binding, dst_binding)) {
                return false;
            }

            if (glsl_seen(dst_binding, src_binding)) {
                return false;
            }
        }
        return true;
    };

    if (!valid(options.bindings.uniform)) {
        diagnostics.AddNote(Source{}) << "when processing uniform";
        return Failure{std::move(diagnostics)};
    }
    if (!valid(options.bindings.storage)) {
        diagnostics.AddNote(Source{}) << "when processing storage";
        return Failure{std::move(diagnostics)};
    }

    if (!valid(options.bindings.sampler)) {
        diagnostics.AddNote(Source{}) << "when processing sampler";
        return Failure{std::move(diagnostics)};
    }

    if (!valid(options.bindings.texture)) {
        diagnostics.AddNote(Source{}) << "when processing texture";
        return Failure{std::move(diagnostics)};
    }
    if (!valid(options.bindings.storage_texture)) {
        diagnostics.AddNote(Source{}) << "when processing storage_texture";
        return Failure{std::move(diagnostics)};
    }

    for (const auto& it : options.bindings.external_texture) {
        const auto& src_binding = it.first;
        const auto& plane0 = it.second.plane0;
        const auto& plane1 = it.second.plane1;
        const auto& metadata = it.second.metadata;

        // Validate with the actual source regardless of what the remapper will do
        if (wgsl_seen(src_binding, plane0)) {
            diagnostics.AddNote(Source{}) << "when processing external_texture";
            return Failure{std::move(diagnostics)};
        }

        if (glsl_seen(plane0, src_binding)) {
            diagnostics.AddNote(Source{}) << "when processing external_texture";
            return Failure{std::move(diagnostics)};
        }
        if (glsl_seen(plane1, src_binding)) {
            diagnostics.AddNote(Source{}) << "when processing external_texture";
            return Failure{std::move(diagnostics)};
        }
        if (glsl_seen(metadata, src_binding)) {
            diagnostics.AddNote(Source{}) << "when processing external_texture";
            return Failure{std::move(diagnostics)};
        }
    }

    return Success;
}

// The remapped binding data and external texture data need to coordinate in order to put
// things in the correct place when we're done. When the data comes in we have a list of all WGSL
// origin (group,binding) pairs to GLSL (binding) in the `uniform`, `storage`, `texture`, and
// `sampler` arrays.
void PopulateBindingInfo(const Options& options,
                         RemapperData& remapper_data,
                         tint::transform::multiplanar::BindingsMap& multiplanar_map) {
    auto create_remappings = [&remapper_data](const auto& hsh) {
        for (const auto& it : hsh) {
            const BindingPoint& src_binding_point = it.first;
            const binding::Uniform& dst_binding_point = it.second;

            // Bindings which go to the same slot in GLSL do not need to be re-bound.
            if (src_binding_point.group == 0 &&
                src_binding_point.binding == dst_binding_point.binding) {
                continue;
            }

            remapper_data.emplace(src_binding_point, BindingPoint{0, dst_binding_point.binding});
        }
    };

    create_remappings(options.bindings.uniform);
    create_remappings(options.bindings.storage);
    create_remappings(options.bindings.texture);
    create_remappings(options.bindings.storage_texture);
    create_remappings(options.bindings.sampler);

    // External textures are re-bound to their plane0 location
    for (const auto& it : options.bindings.external_texture) {
        const BindingPoint& src_binding_point = it.first;

        const binding::BindingInfo& plane0 = it.second.plane0;
        const binding::BindingInfo& plane1 = it.second.plane1;
        const binding::BindingInfo& metadata = it.second.metadata;

        const BindingPoint plane0_binding_point{0, plane0.binding};
        const BindingPoint plane1_binding_point{0, plane1.binding};
        const BindingPoint metadata_binding_point{0, metadata.binding};

        // Use the re-bound glsl plane0 value for the lookup key.
        multiplanar_map.emplace(BindingPoint{0, plane0_binding_point.binding},
                                tint::transform::multiplanar::BindingPoints{
                                    plane1_binding_point, metadata_binding_point});

        // Bindings which go to the same slot in GLSL do not need to be re-bound.
        if (src_binding_point == plane0_binding_point) {
            continue;
        }

        remapper_data.emplace(src_binding_point, plane0_binding_point);
    }

    // Update the non-plane1 bindings in the combined texture sampler info to be the
    // remapped bindings.
    for (const auto& it : options.bindings.sampler_texture_to_name) {
        auto pair = it.first;
        auto name = it.second;

        // Move the non-external textures to the new binding points
        if (!pair.is_external_plane1) {
            pair.texture.group = 0;
            pair.sampler.group = 0;

            auto tex = options.bindings.texture.find(pair.texture);
            if (tex != options.bindings.texture.end()) {
                pair.texture.binding = tex->second.binding;
            }

            auto samp = options.bindings.sampler.find(pair.sampler);
            if (samp != options.bindings.sampler.end()) {
                pair.sampler.binding = samp->second.binding;
            }
        }
    }
}

}  // namespace tint::glsl::writer