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

#include <utility>

#include "src/tint/lang/core/ir/builder.h"
#include "src/tint/lang/core/ir/validator.h"
#include "src/tint/lang/msl/ir/builtin_call.h"

namespace tint::msl::writer::raise {
namespace {

/// 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()};

    /// Process the module.
    void Process() {
        // Find the binary operators that need replacing.
        Vector<core::ir::CoreBinary*, 4> fmod_worklist;
        Vector<core::ir::CoreBinary*, 4> logical_bool_worklist;
        for (auto* inst : ir.Instructions()) {
            if (auto* binary = inst->As<core::ir::CoreBinary>()) {
                if (binary->Op() == core::BinaryOp::kModulo &&
                    binary->LHS()->Type()->is_float_scalar_or_vector()) {
                    fmod_worklist.Push(binary);
                } else if ((binary->Op() == core::BinaryOp::kAnd ||
                            binary->Op() == core::BinaryOp::kOr) &&
                           binary->LHS()->Type()->is_bool_scalar_or_vector()) {
                    logical_bool_worklist.Push(binary);
                }
            }
        }

        // Replace the instructions that we found.
        for (auto* fmod : fmod_worklist) {
            FMod(fmod);
        }
        for (auto* logical_bool : logical_bool_worklist) {
            LogicalBool(logical_bool);
        }
    }

    /// Replace a floating point modulo binary instruction with the equivalent MSL intrinsic.
    /// @param binary the float point modulo binary instruction
    void FMod(core::ir::CoreBinary* binary) {
        auto* call = b.CallWithResult<msl::ir::BuiltinCall>(
            binary->DetachResult(), msl::BuiltinFn::kFmod, binary->Operands());
        call->InsertBefore(binary);
        binary->Destroy();
    }

    /// Replace a logical boolean binary instruction.
    /// @param binary the logical boolean binary instruction
    void LogicalBool(core::ir::CoreBinary* binary) {
        // MSL does not have boolean overloads for `&` and `|`, so it promotes the operands to
        // integers. Make this explicit in the IR and then convert the result of the binary
        // instruction back to a boolean.
        auto* result_ty = binary->Result(0)->Type();
        const core::type::Type* int_ty = ty.u32();
        if (auto* vec = result_ty->As<core::type::Vector>()) {
            int_ty = ty.vec(int_ty, vec->Width());
        }
        b.InsertBefore(binary, [&] {
            auto* int_lhs = b.Convert(int_ty, binary->LHS());
            auto* int_rhs = b.Convert(int_ty, binary->RHS());
            auto* int_binary = b.Binary(binary->Op(), int_ty, int_lhs, int_rhs);
            b.ConvertWithResult(binary->DetachResult(), int_binary);
        });
        binary->Destroy();
    }
};

}  // namespace

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

    State{ir}.Process();

    return Success;
}

}  // namespace tint::msl::writer::raise