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

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#include "src/tint/lang/glsl/writer/raise/binary_polyfill.h"

#include "src/tint/lang/core/fluent_types.h"  // IWYU pragma: export
#include "src/tint/lang/core/ir/builder.h"
#include "src/tint/lang/core/ir/module.h"
#include "src/tint/lang/core/ir/validator.h"
#include "src/tint/lang/core/type/manager.h"
#include "src/tint/lang/glsl/ir/builtin_call.h"

namespace tint::glsl::writer::raise {
namespace {

using namespace tint::core::fluent_types;     // NOLINT
using namespace tint::core::number_suffixes;  // NOLINT

/// PIMPL state for the transform.
struct State {
    /// The IR module.
    core::ir::Module& ir;

    /// The IR builder.
    core::ir::Builder b{ir};

    /// The type manager.
    core::type::Manager& ty{ir.Types()};

    /// Float modulo polyfills
    Hashmap<const core::type::Type*, core::ir::Function*, 4> float_modulo_funcs_{};

    /// Process the module.
    void Process() {
        // Find the binary instructions that need replacing.
        Vector<core::ir::Binary*, 4> binary_worklist;
        for (auto* inst : ir.Instructions()) {
            if (auto* binary = inst->As<core::ir::Binary>()) {
                switch (binary->Op()) {
                    case core::BinaryOp::kAnd:
                    case core::BinaryOp::kOr: {
                        if (binary->LHS()->Type()->IsBoolScalarOrVector()) {
                            binary_worklist.Push(binary);
                        }
                        break;
                    }
                    case core::BinaryOp::kModulo: {
                        if (binary->LHS()->Type()->IsFloatScalarOrVector()) {
                            binary_worklist.Push(binary);
                        }
                        break;
                    }
                    case core::BinaryOp::kEqual:
                    case core::BinaryOp::kNotEqual:
                    case core::BinaryOp::kLessThan:
                    case core::BinaryOp::kGreaterThan:
                    case core::BinaryOp::kLessThanEqual:
                    case core::BinaryOp::kGreaterThanEqual:
                        if (!binary->LHS()->Type()->Is<core::type::Scalar>()) {
                            binary_worklist.Push(binary);
                        }
                        break;
                    default:
                        break;
                }
                continue;
            }
        }

        // Replace the binary calls
        for (auto* binary : binary_worklist) {
            switch (binary->Op()) {
                case core::BinaryOp::kAnd:
                case core::BinaryOp::kOr:
                    BitwiseBoolean(binary);
                    break;
                case core::BinaryOp::kModulo:
                    FloatModulo(binary);
                    break;
                case core::BinaryOp::kEqual:
                case core::BinaryOp::kNotEqual:
                case core::BinaryOp::kLessThan:
                case core::BinaryOp::kGreaterThan:
                case core::BinaryOp::kLessThanEqual:
                case core::BinaryOp::kGreaterThanEqual:
                    ConvertRelational(binary);
                    break;
                default:
                    TINT_UNIMPLEMENTED();
            }
        }
    }

    void ConvertRelational(core::ir::Binary* binary) {
        glsl::BuiltinFn func = glsl::BuiltinFn::kNone;
        switch (binary->Op()) {
            case core::BinaryOp::kEqual:
                func = glsl::BuiltinFn::kEqual;
                break;
            case core::BinaryOp::kNotEqual:
                func = glsl::BuiltinFn::kNotEqual;
                break;
            case core::BinaryOp::kLessThan:
                func = glsl::BuiltinFn::kLessThan;
                break;
            case core::BinaryOp::kGreaterThan:
                func = glsl::BuiltinFn::kGreaterThan;
                break;
            case core::BinaryOp::kLessThanEqual:
                func = glsl::BuiltinFn::kLessThanEqual;
                break;
            case core::BinaryOp::kGreaterThanEqual:
                func = glsl::BuiltinFn::kGreaterThanEqual;
                break;
            default:
                TINT_UNREACHABLE();
        }
        b.InsertBefore(binary, [&] {
            b.CallWithResult<glsl::ir::BuiltinCall>(binary->DetachResult(), func, binary->LHS(),
                                                    binary->RHS());
        });
        binary->Destroy();
    }

    void BitwiseBoolean(core::ir::Binary* binary) {
        b.InsertBefore(binary, [&] {
            auto* res_ty = ty.MatchWidth(ty.u32(), binary->Result(0)->Type());
            auto* lhs = b.Convert(res_ty, binary->LHS());
            auto* rhs = b.Convert(res_ty, binary->RHS());

            core::ir::Value* result = nullptr;
            switch (binary->Op()) {
                case core::BinaryOp::kAnd:
                    result = b.And(res_ty, lhs, rhs)->Result(0);
                    break;
                case core::BinaryOp::kOr:
                    result = b.Or(res_ty, lhs, rhs)->Result(0);
                    break;
                default:
                    TINT_UNREACHABLE();
            }
            b.ConvertWithResult(binary->DetachResult(), result);
        });
        binary->Destroy();
    }

    core::ir::Function* CreateFloatModuloPolyfill(const core::type::Type* type) {
        return float_modulo_funcs_.GetOrAdd(type, [&]() -> core::ir::Function* {
            auto* f = b.Function("tint_float_modulo", type);
            auto* x = b.FunctionParam("x", type);
            auto* y = b.FunctionParam("y", type);
            f->SetParams({x, y});

            b.Append(f->Block(), [&] {
                core::ir::Value* ret = nullptr;

                ret = b.Divide(type, x, y)->Result(0);
                ret = b.Call(type, core::BuiltinFn::kTrunc, ret)->Result(0);
                ret = b.Multiply(type, y, ret)->Result(0);
                ret = b.Subtract(type, x, ret)->Result(0);
                b.Return(f, ret);
            });
            return f;
        });
    }

    void FloatModulo(core::ir::Binary* binary) {
        b.InsertBefore(binary, [&] {
            auto* lhs = binary->LHS();
            auto* rhs = binary->RHS();

            auto* res_ty = binary->Result(0)->Type();

            // The WGSL modulo either takes two of the same types, which would then match the
            // result type, or a mixed scalar/vector combination. The vector type would then match
            // the result type. If we have a mixed scalar/vector, construct a vector of the scalar
            // type which makes the polyfill simpler.
            if (lhs->Type() != res_ty) {
                lhs = b.Construct(res_ty, lhs)->Result(0);
            }
            if (rhs->Type() != res_ty) {
                rhs = b.Construct(res_ty, rhs)->Result(0);
            }

            auto* func = CreateFloatModuloPolyfill(res_ty);
            b.CallWithResult(binary->DetachResult(), func, lhs, rhs);
        });
        binary->Destroy();
    }
};

}  // namespace

Result<SuccessType> BinaryPolyfill(core::ir::Module& ir) {
    auto result = ValidateAndDumpIfNeeded(ir, "glsl.BinaryPolyfill transform");
    if (result != Success) {
        return result.Failure();
    }

    State{ir}.Process();

    return Success;
}

}  // namespace tint::glsl::writer::raise