src/tint/lang/spirv/writer/raise/replace_unsigned_compare_zero.cc

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#include "src/tint/lang/spirv/writer/raise/replace_unsigned_compare_zero.h"

#include "src/tint/lang/core/ir/builder.h"
#include "src/tint/lang/core/ir/constant.h"
#include "src/tint/lang/core/ir/core_binary.h"
#include "src/tint/lang/core/ir/module.h"
#include "src/tint/lang/core/ir/validator.h"

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

namespace tint::spirv::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};

    /// Process the module.
    void Process() {
        for (auto* inst : ir.Instructions()) {
            auto* binary = inst->As<core::ir::CoreBinary>();
            if (!binary || binary->Op() != core::BinaryOp::kEqual) {
                continue;
            }

            if (!binary->LHS()->Type()->DeepestElement()->Is<core::type::U32>()) {
                continue;
            }

            if (IsConstantZero(binary->RHS())) {
                binary->SetOp(core::BinaryOp::kLessThan);
                binary->SetOperand(core::ir::Binary::kRhsOperandOffset,
                                   b.MatchWidth(1_u, binary->RHS()->Type()));
            } else if (IsConstantZero(binary->LHS())) {
                binary->SetOp(core::BinaryOp::kGreaterThan);
                binary->SetOperand(core::ir::Binary::kLhsOperandOffset,
                                   b.MatchWidth(1_u, binary->LHS()->Type()));
            }
        }
    }

    /// @returns true if @p val is a constant zero value
    bool IsConstantZero(const core::ir::Value* val) {
        if (auto* c = val->As<core::ir::Constant>()) {
            return c->Value()->AllZero();
        }
        return false;
    }
};

}  // namespace

Result<SuccessType> ReplaceUnsignedCompareZero(core::ir::Module& ir) {
    AssertValid(ir, "before spirv.ReplaceUnsignedCompareZero");

    State{ir}.Process();

    return Success;
}

}  // namespace tint::spirv::writer::raise