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

// Copyright 2021 The Dawn & Tint Authors
//
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//    this list of conditions and the following disclaimer in the documentation
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#include "src/tint/lang/glsl/writer/writer.h"

#include <vector>
#include "src/tint/lang/core/ir/core_builtin_call.h"
#include "src/tint/lang/core/ir/module.h"
#include "src/tint/lang/core/ir/validator.h"
#include "src/tint/lang/core/ir/var.h"
#include "src/tint/lang/core/type/binding_array.h"
#include "src/tint/lang/core/type/pointer.h"
#include "src/tint/lang/core/type/storage_texture.h"
#include "src/tint/lang/core/type/texel_buffer.h"
#include "src/tint/lang/glsl/writer/common/option_helpers.h"
#include "src/tint/lang/glsl/writer/printer/printer.h"
#include "src/tint/lang/glsl/writer/raise/raise.h"

namespace tint::glsl::writer {

Result<SuccessType> CanGenerate(const core::ir::Module& ir, const Options& options) {
    // Check for unsupported types.
    for (auto* ty : ir.Types()) {
        if (ty->Is<core::type::SubgroupMatrix>()) {
            return Failure("subgroup matrices are not supported by the GLSL backend");
        }
        if (ty->Is<core::type::ResourceBinding>()) {
            return Failure("resource_binding not supported by the GLSL backend");
        }
        if (ty->Is<core::type::TexelBuffer>()) {
            // TODO(crbug/382544164): Prototype texel buffer feature
            return Failure("texel buffers are not supported by the GLSL backend");
        }
        if (auto* ba = ty->As<core::type::BindingArray>()) {
            if (ba->Count()->Is<core::type::RuntimeArrayCount>()) {
                return Failure("runtime binding array not supported by the GLSL backend");
            }
        }
    }

    // Make sure that every texture variable is in the texture_builtins_from_uniform binding list,
    // otherwise TextureBuiltinsFromUniform will fail.
    // TODO(https://issues.chromium.org/427172887) Be more precise for the
    // texture_builtins_from_uniform checks. Also ensure there is at most one user-declared
    // immediate.
    for (auto* inst : *ir.root_block) {
        auto* var = inst->As<core::ir::Var>();

        if (!var) {
            continue;
        }
        auto* ptr = var->Result()->Type()->As<core::type::Pointer>();

        // The pixel_local extension is not supported by the GLSL backend.
        if (ptr->AddressSpace() == core::AddressSpace::kPixelLocal) {
            return Failure("pixel_local address space is not supported by the GLSL backend");
        }

        if (ptr->AddressSpace() == core::AddressSpace::kHandle) {
            const core::type::Type* handle_type = ptr->StoreType();
            uint32_t count = 1;
            if (auto* ba = handle_type->As<core::type::BindingArray>()) {
                handle_type = ba->ElemType();
                count = ba->Count()->As<core::type::ConstantArrayCount>()->value;
            }

            // Check texture types that need metadata for texture_builtins_from_uniform.
            if (handle_type->Is<core::type::Texture>() &&
                !handle_type->IsAnyOf<core::type::StorageTexture, core::type::ExternalTexture>()) {
                bool found = false;
                auto binding = options.bindings.texture.at(var->BindingPoint().value());
                for (auto& bp : options.bindings.texture_builtins_from_uniform.ubo_contents) {
                    if (bp.binding == binding) {
                        if (bp.count < count) {
                            return Failure(
                                "binding_array of textures doesn't have enough data in "
                                "texture_builtins_from_uniform list");
                        }
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    return Failure("texture missing from texture_builtins_from_uniform list");
                }
            }

            // Check texel formats for read-write storage textures when targeting ES.
            if (options.version.IsES()) {
                if (auto* st = handle_type->As<core::type::StorageTexture>()) {
                    if (st->Access() == core::Access::kReadWrite) {
                        switch (st->TexelFormat()) {
                            case core::TexelFormat::kR32Float:
                            case core::TexelFormat::kR32Sint:
                            case core::TexelFormat::kR32Uint:
                                break;
                            default:
                                return Failure("unsupported read-write storage texture format");
                        }
                    }
                }
            }
        }

        // user-declared immediate validation handled later by helper.
    }

    auto user_immediate_res = core::ir::ValidateSingleUserImmediate(ir);
    if (user_immediate_res != Success) {
        return user_immediate_res.Failure();
    }

    uint32_t user_immediate_size = user_immediate_res.Get();

    // Check for calls to unsupported builtin functions.
    for (auto* inst : ir.Instructions()) {
        auto* call = inst->As<core::ir::CoreBuiltinCall>();
        if (!call) {
            continue;
        }

        if (core::IsSubgroup(call->Func())) {
            return Failure("subgroups are not supported by the GLSL backend");
        }
        if (call->Func() == core::BuiltinFn::kInputAttachmentLoad) {
            return Failure("input attachments are not supported by the GLSL backend");
        }
    }

    // Check for unsupported shader IO builtins.
    for (auto& func : ir.functions) {
        if (!func->IsEntryPoint()) {
            continue;
        }

        // subgroup builtins are not supported.
        for (auto* param : func->Params()) {
            if (auto* str = param->Type()->As<core::type::Struct>()) {
                for (auto* member : str->Members()) {
                    if (member->Attributes().builtin == core::BuiltinValue::kSubgroupId ||
                        member->Attributes().builtin == core::BuiltinValue::kSubgroupInvocationId ||
                        member->Attributes().builtin == core::BuiltinValue::kSubgroupSize) {
                        return Failure("subgroups are not supported by the GLSL backend");
                    }
                }
            } else {
                if (param->Builtin() == core::BuiltinValue::kSubgroupId ||
                    param->Builtin() == core::BuiltinValue::kSubgroupInvocationId ||
                    param->Builtin() == core::BuiltinValue::kSubgroupSize) {
                    return Failure("subgroups are not supported by the GLSL backend");
                }
            }
        }

        // clip_distance is not supported.
        if (auto* str = func->ReturnType()->As<core::type::Struct>()) {
            for (auto* member : str->Members()) {
                if (member->Attributes().builtin == core::BuiltinValue::kClipDistances) {
                    return Failure("clip_distances is not supported by the GLSL backend");
                }
            }
        }
    }

    {
        std::vector<core::ir::ImmediateInfo> immediates;
        if (options.first_instance_offset) {
            immediates.push_back({*options.first_instance_offset, 4u});
        }
        if (options.first_vertex_offset) {
            immediates.push_back({*options.first_vertex_offset, 4u});
        }
        if (options.depth_range_offsets) {
            immediates.push_back({options.depth_range_offsets->max, 4u});
            immediates.push_back({options.depth_range_offsets->min, 4u});
        }
        if (auto res =
                core::ir::ValidateInternalImmediateOffset(0x1000, user_immediate_size, immediates);
            res != Success) {
            return res.Failure();
        }
    }

    {
        auto res = ValidateBindingOptions(options);
        if (res != Success) {
            return res.Failure();
        }
    }

    return Success;
}

Result<Output> Generate(core::ir::Module& ir, const Options& options) {
    // Raise from core-dialect to GLSL-dialect.
    if (auto res = Raise(ir, options); res != Success) {
        return res.Failure();
    }

    return Print(ir, options);
}

}  // namespace tint::glsl::writer