Adds flang/include/flang/Common/log2-visit.h, which defines a Fortran::common::visit() template function that is a drop-in replacement for std::visit(). Modifies most use sites in the front-end and runtime to use common::visit(). The C++ standard mandates that std::visit() have O(1) execution time, which forces implementations to build dispatch tables. This new common::visit() is O(log2 N) in the number of alternatives in a variant<>, but that N tends to be small and so this change produces a fairly significant improvement in compiler build memory requirements, a 5-10% improvement in compiler build time, and a small improvement in compiler execution time. Building with -DFLANG_USE_STD_VISIT causes common::visit() to be an alias for std::visit(). Calls to common::visit() with multiple variant arguments are referred to std::visit(), pending further work. This change is enabled only for GCC builds with GCC >= 9; an earlier attempt (D122441) ran into bugs in some versions of clang and was reverted rather than simply disabled; and it is not well tested with MSVC. In non-GCC and older GCC builds, common::visit() is simply an alias for std::visit().
174 lines
5.5 KiB
C++
174 lines
5.5 KiB
C++
//===-- lib/Parser/tools.cpp ----------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "flang/Parser/tools.h"
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namespace Fortran::parser {
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const Name &GetLastName(const Name &x) { return x; }
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const Name &GetLastName(const StructureComponent &x) {
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return GetLastName(x.component);
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}
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const Name &GetLastName(const DataRef &x) {
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return common::visit(
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common::visitors{
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[](const Name &name) -> const Name & { return name; },
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[](const common::Indirection<StructureComponent> &sc)
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-> const Name & { return GetLastName(sc.value()); },
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[](const common::Indirection<ArrayElement> &sc) -> const Name & {
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return GetLastName(sc.value().base);
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},
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[](const common::Indirection<CoindexedNamedObject> &ci)
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-> const Name & { return GetLastName(ci.value().base); },
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},
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x.u);
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}
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const Name &GetLastName(const Substring &x) {
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return GetLastName(std::get<DataRef>(x.t));
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}
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const Name &GetLastName(const Designator &x) {
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return common::visit(
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[](const auto &y) -> const Name & { return GetLastName(y); }, x.u);
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}
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const Name &GetLastName(const ProcComponentRef &x) {
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return GetLastName(x.v.thing);
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}
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const Name &GetLastName(const ProcedureDesignator &x) {
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return common::visit(
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[](const auto &y) -> const Name & { return GetLastName(y); }, x.u);
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}
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const Name &GetLastName(const Call &x) {
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return GetLastName(std::get<ProcedureDesignator>(x.t));
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}
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const Name &GetLastName(const FunctionReference &x) { return GetLastName(x.v); }
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const Name &GetLastName(const Variable &x) {
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return common::visit(
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[](const auto &indirection) -> const Name & {
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return GetLastName(indirection.value());
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},
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x.u);
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}
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const Name &GetLastName(const AllocateObject &x) {
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return common::visit(
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[](const auto &y) -> const Name & { return GetLastName(y); }, x.u);
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}
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const Name &GetFirstName(const Name &x) { return x; }
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const Name &GetFirstName(const StructureComponent &x) {
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return GetFirstName(x.base);
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}
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const Name &GetFirstName(const DataRef &x) {
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return common::visit(
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common::visitors{
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[](const Name &name) -> const Name & { return name; },
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[](const common::Indirection<StructureComponent> &sc)
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-> const Name & { return GetFirstName(sc.value()); },
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[](const common::Indirection<ArrayElement> &sc) -> const Name & {
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return GetFirstName(sc.value().base);
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},
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[](const common::Indirection<CoindexedNamedObject> &ci)
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-> const Name & { return GetFirstName(ci.value().base); },
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},
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x.u);
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}
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const Name &GetFirstName(const Substring &x) {
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return GetFirstName(std::get<DataRef>(x.t));
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}
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const Name &GetFirstName(const Designator &x) {
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return common::visit(
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[](const auto &y) -> const Name & { return GetFirstName(y); }, x.u);
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}
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const Name &GetFirstName(const ProcComponentRef &x) {
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return GetFirstName(x.v.thing);
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}
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const Name &GetFirstName(const ProcedureDesignator &x) {
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return common::visit(
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[](const auto &y) -> const Name & { return GetFirstName(y); }, x.u);
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}
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const Name &GetFirstName(const Call &x) {
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return GetFirstName(std::get<ProcedureDesignator>(x.t));
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}
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const Name &GetFirstName(const FunctionReference &x) {
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return GetFirstName(x.v);
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}
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const Name &GetFirstName(const Variable &x) {
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return common::visit(
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[](const auto &indirect) -> const Name & {
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return GetFirstName(indirect.value());
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},
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x.u);
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}
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const CoindexedNamedObject *GetCoindexedNamedObject(const DataRef &base) {
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return common::visit(
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common::visitors{
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[](const Name &) -> const CoindexedNamedObject * { return nullptr; },
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[](const common::Indirection<CoindexedNamedObject> &x)
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-> const CoindexedNamedObject * { return &x.value(); },
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[](const auto &x) -> const CoindexedNamedObject * {
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return GetCoindexedNamedObject(x.value().base);
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},
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},
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base.u);
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}
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const CoindexedNamedObject *GetCoindexedNamedObject(
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const Designator &designator) {
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return common::visit(
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common::visitors{
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[](const DataRef &x) -> const CoindexedNamedObject * {
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return GetCoindexedNamedObject(x);
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},
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[](const Substring &x) -> const CoindexedNamedObject * {
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return GetCoindexedNamedObject(std::get<DataRef>(x.t));
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},
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},
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designator.u);
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}
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const CoindexedNamedObject *GetCoindexedNamedObject(const Variable &variable) {
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return common::visit(
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common::visitors{
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[](const common::Indirection<Designator> &designator)
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-> const CoindexedNamedObject * {
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return GetCoindexedNamedObject(designator.value());
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},
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[](const auto &) -> const CoindexedNamedObject * { return nullptr; },
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},
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variable.u);
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}
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const CoindexedNamedObject *GetCoindexedNamedObject(
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const AllocateObject &allocateObject) {
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return common::visit(
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common::visitors{
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[](const StructureComponent &x) -> const CoindexedNamedObject * {
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return GetCoindexedNamedObject(x.base);
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},
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[](const auto &) -> const CoindexedNamedObject * { return nullptr; },
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},
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allocateObject.u);
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}
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} // namespace Fortran::parser
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