[OpenMP] Deprecate the old driver for OpenMP offloading

Recently OpenMP has transitioned to using the "new" driver which
primarily merges the device and host linking phases into a single
wrapper that handles both at the same time. This replaced a few tools
that were only used for OpenMP offloading, such as the
`clang-offload-wrapper` and `clang-nvlink-wrapper`. The new driver
carries some marked benefits compared to the old driver that is now
being deprecated. Things like device-side LTO, static library
support, and more compatible tooling. As such, we should be able to
completely deprecate the old driver, at least for OpenMP. The old driver
support will still exist for CUDA and HIP, although both of these can
currently be compiled on Linux with `--offload-new-driver` to use the new
method.

Note that this does not deprecate the `clang-offload-bundler`, although
it is unused by OpenMP now, it is still used by the HIP toolchain both
as their device binary format and object format.

When I proposed deprecating this code I heard some vendors voice
concernes about needing to update their code in their fork. They should
be able to just revert this commit if it lands.

Reviewed By: jdoerfert, MaskRay, ye-luo

Differential Revision: https://reviews.llvm.org/D130020

Author: jhuber6

clang/include/clang/Driver/Action.h

@@ -73,7 +73,6 @@ class Action {
     VerifyPCHJobClass,
     OffloadBundlingJobClass,
     OffloadUnbundlingJobClass,
-    OffloadWrapperJobClass,
     OffloadPackagerJobClass,
     LinkerWrapperJobClass,
     StaticLibJobClass,
@@ -659,17 +658,6 @@ class OffloadUnbundlingJobAction final : public JobAction {
   }
 };
 
-class OffloadWrapperJobAction : public JobAction {
-  void anchor() override;
-
-public:
-  OffloadWrapperJobAction(ActionList &Inputs, types::ID Type);
-
-  static bool classof(const Action *A) {
-    return A->getKind() == OffloadWrapperJobClass;
-  }
-};
-
 class OffloadPackagerJobAction : public JobAction {
   void anchor() override;
 

clang/include/clang/Driver/ToolChain.h

@@ -150,7 +150,6 @@ class ToolChain {
   mutable std::unique_ptr<Tool> StaticLibTool;
   mutable std::unique_ptr<Tool> IfsMerge;
   mutable std::unique_ptr<Tool> OffloadBundler;
-  mutable std::unique_ptr<Tool> OffloadWrapper;
   mutable std::unique_ptr<Tool> OffloadPackager;
   mutable std::unique_ptr<Tool> LinkerWrapper;
 
@@ -162,7 +161,6 @@ class ToolChain {
   Tool *getIfsMerge() const;
   Tool *getClangAs() const;
   Tool *getOffloadBundler() const;
-  Tool *getOffloadWrapper() const;
   Tool *getOffloadPackager() const;
   Tool *getLinkerWrapper() const;
 

clang/lib/Driver/Action.cpp

@@ -43,8 +43,6 @@ const char *Action::getClassName(ActionClass AC) {
     return "clang-offload-bundler";
   case OffloadUnbundlingJobClass:
     return "clang-offload-unbundler";
-  case OffloadWrapperJobClass:
-    return "clang-offload-wrapper";
   case OffloadPackagerJobClass:
     return "clang-offload-packager";
   case LinkerWrapperJobClass:
@@ -428,12 +426,6 @@ void OffloadUnbundlingJobAction::anchor() {}
 OffloadUnbundlingJobAction::OffloadUnbundlingJobAction(Action *Input)
     : JobAction(OffloadUnbundlingJobClass, Input, Input->getType()) {}
 
-void OffloadWrapperJobAction::anchor() {}
-
-OffloadWrapperJobAction::OffloadWrapperJobAction(ActionList &Inputs,
-                                                 types::ID Type)
-  : JobAction(OffloadWrapperJobClass, Inputs, Type) {}
-
 void OffloadPackagerJobAction::anchor() {}
 
 OffloadPackagerJobAction::OffloadPackagerJobAction(ActionList &Inputs,

clang/lib/Driver/Driver.cpp

@@ -3441,178 +3441,6 @@ class OffloadingActionBuilder final {
     void appendLinkDependences(OffloadAction::DeviceDependences &DA) override {}
   };
 
-  /// OpenMP action builder. The host bitcode is passed to the device frontend
-  /// and all the device linked images are passed to the host link phase.
-  class OpenMPActionBuilder final : public DeviceActionBuilder {
-    /// The OpenMP actions for the current input.
-    ActionList OpenMPDeviceActions;
-
-    /// The linker inputs obtained for each toolchain.
-    SmallVector<ActionList, 8> DeviceLinkerInputs;
-
-  public:
-    OpenMPActionBuilder(Compilation &C, DerivedArgList &Args,
-                        const Driver::InputList &Inputs)
-        : DeviceActionBuilder(C, Args, Inputs, Action::OFK_OpenMP) {}
-
-    ActionBuilderReturnCode
-    getDeviceDependences(OffloadAction::DeviceDependences &DA,
-                         phases::ID CurPhase, phases::ID FinalPhase,
-                         PhasesTy &Phases) override {
-      if (OpenMPDeviceActions.empty())
-        return ABRT_Inactive;
-
-      // We should always have an action for each input.
-      assert(OpenMPDeviceActions.size() == ToolChains.size() &&
-             "Number of OpenMP actions and toolchains do not match.");
-
-      // The host only depends on device action in the linking phase, when all
-      // the device images have to be embedded in the host image.
-      if (CurPhase == phases::Link) {
-        assert(ToolChains.size() == DeviceLinkerInputs.size() &&
-               "Toolchains and linker inputs sizes do not match.");
-        auto LI = DeviceLinkerInputs.begin();
-        for (auto *A : OpenMPDeviceActions) {
-          LI->push_back(A);
-          ++LI;
-        }
-
-        // We passed the device action as a host dependence, so we don't need to
-        // do anything else with them.
-        OpenMPDeviceActions.clear();
-        return ABRT_Success;
-      }
-
-      // By default, we produce an action for each device arch.
-      for (Action *&A : OpenMPDeviceActions)
-        A = C.getDriver().ConstructPhaseAction(C, Args, CurPhase, A);
-
-      return ABRT_Success;
-    }
-
-    ActionBuilderReturnCode addDeviceDepences(Action *HostAction) override {
-
-      // If this is an input action replicate it for each OpenMP toolchain.
-      if (auto *IA = dyn_cast<InputAction>(HostAction)) {
-        OpenMPDeviceActions.clear();
-        for (unsigned I = 0; I < ToolChains.size(); ++I)
-          OpenMPDeviceActions.push_back(
-              C.MakeAction<InputAction>(IA->getInputArg(), IA->getType()));
-        return ABRT_Success;
-      }
-
-      // If this is an unbundling action use it as is for each OpenMP toolchain.
-      if (auto *UA = dyn_cast<OffloadUnbundlingJobAction>(HostAction)) {
-        OpenMPDeviceActions.clear();
-        auto *IA = cast<InputAction>(UA->getInputs().back());
-        std::string FileName = IA->getInputArg().getAsString(Args);
-        // Check if the type of the file is the same as the action. Do not
-        // unbundle it if it is not. Do not unbundle .so files, for example,
-        // which are not object files.
-        if (IA->getType() == types::TY_Object &&
-            (!llvm::sys::path::has_extension(FileName) ||
-             types::lookupTypeForExtension(
-                 llvm::sys::path::extension(FileName).drop_front()) !=
-                 types::TY_Object))
-          return ABRT_Inactive;
-        for (unsigned I = 0; I < ToolChains.size(); ++I) {
-          OpenMPDeviceActions.push_back(UA);
-          UA->registerDependentActionInfo(
-              ToolChains[I], /*BoundArch=*/StringRef(), Action::OFK_OpenMP);
-        }
-        return ABRT_Success;
-      }
-
-      // When generating code for OpenMP we use the host compile phase result as
-      // a dependence to the device compile phase so that it can learn what
-      // declarations should be emitted. However, this is not the only use for
-      // the host action, so we prevent it from being collapsed.
-      if (isa<CompileJobAction>(HostAction)) {
-        HostAction->setCannotBeCollapsedWithNextDependentAction();
-        assert(ToolChains.size() == OpenMPDeviceActions.size() &&
-               "Toolchains and device action sizes do not match.");
-        OffloadAction::HostDependence HDep(
-            *HostAction, *C.getSingleOffloadToolChain<Action::OFK_Host>(),
-            /*BoundArch=*/nullptr, Action::OFK_OpenMP);
-        auto TC = ToolChains.begin();
-        for (Action *&A : OpenMPDeviceActions) {
-          assert(isa<CompileJobAction>(A));
-          OffloadAction::DeviceDependences DDep;
-          DDep.add(*A, **TC, /*BoundArch=*/nullptr, Action::OFK_OpenMP);
-          A = C.MakeAction<OffloadAction>(HDep, DDep);
-          ++TC;
-        }
-      }
-      return ABRT_Success;
-    }
-
-    void appendTopLevelActions(ActionList &AL) override {
-      if (OpenMPDeviceActions.empty())
-        return;
-
-      // We should always have an action for each input.
-      assert(OpenMPDeviceActions.size() == ToolChains.size() &&
-             "Number of OpenMP actions and toolchains do not match.");
-
-      // Append all device actions followed by the proper offload action.
-      auto TI = ToolChains.begin();
-      for (auto *A : OpenMPDeviceActions) {
-        OffloadAction::DeviceDependences Dep;
-        Dep.add(*A, **TI, /*BoundArch=*/nullptr, Action::OFK_OpenMP);
-        AL.push_back(C.MakeAction<OffloadAction>(Dep, A->getType()));
-        ++TI;
-      }
-      // We no longer need the action stored in this builder.
-      OpenMPDeviceActions.clear();
-    }
-
-    void appendLinkDeviceActions(ActionList &AL) override {
-      assert(ToolChains.size() == DeviceLinkerInputs.size() &&
-             "Toolchains and linker inputs sizes do not match.");
-
-      // Append a new link action for each device.
-      auto TC = ToolChains.begin();
-      for (auto &LI : DeviceLinkerInputs) {
-        auto *DeviceLinkAction =
-            C.MakeAction<LinkJobAction>(LI, types::TY_Image);
-        OffloadAction::DeviceDependences DeviceLinkDeps;
-        DeviceLinkDeps.add(*DeviceLinkAction, **TC, /*BoundArch=*/nullptr,
-		        Action::OFK_OpenMP);
-        AL.push_back(C.MakeAction<OffloadAction>(DeviceLinkDeps,
-            DeviceLinkAction->getType()));
-        ++TC;
-      }
-      DeviceLinkerInputs.clear();
-    }
-
-    Action* appendLinkHostActions(ActionList &AL) override {
-      // Create wrapper bitcode from the result of device link actions and compile
-      // it to an object which will be added to the host link command.
-      auto *BC = C.MakeAction<OffloadWrapperJobAction>(AL, types::TY_LLVM_BC);
-      auto *ASM = C.MakeAction<BackendJobAction>(BC, types::TY_PP_Asm);
-      return C.MakeAction<AssembleJobAction>(ASM, types::TY_Object);
-    }
-
-    void appendLinkDependences(OffloadAction::DeviceDependences &DA) override {}
-
-    bool initialize() override {
-      // Get the OpenMP toolchains. If we don't get any, the action builder will
-      // know there is nothing to do related to OpenMP offloading.
-      auto OpenMPTCRange = C.getOffloadToolChains<Action::OFK_OpenMP>();
-      for (auto TI = OpenMPTCRange.first, TE = OpenMPTCRange.second; TI != TE;
-           ++TI)
-        ToolChains.push_back(TI->second);
-
-      DeviceLinkerInputs.resize(ToolChains.size());
-      return false;
-    }
-
-    bool canUseBundlerUnbundler() const override {
-      // OpenMP should use bundled files whenever possible.
-      return true;
-    }
-  };
-
   ///
   /// TODO: Add the implementation for other specialized builders here.
   ///
@@ -3637,9 +3465,6 @@ class OffloadingActionBuilder final {
     // Create a specialized builder for HIP.
     SpecializedBuilders.push_back(new HIPActionBuilder(C, Args, Inputs));
 
-    // Create a specialized builder for OpenMP.
-    SpecializedBuilders.push_back(new OpenMPActionBuilder(C, Args, Inputs));
-
     //
     // TODO: Build other specialized builders here.
     //
@@ -5505,14 +5330,6 @@ InputInfoList Driver::BuildJobsForActionNoCache(
         /*CreatePrefixForHost=*/isa<OffloadPackagerJobAction>(A) ||
             !(A->getOffloadingHostActiveKinds() == Action::OFK_None ||
               AtTopLevel));
-    if (isa<OffloadWrapperJobAction>(JA)) {
-      if (Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o))
-        BaseInput = FinalOutput->getValue();
-      else
-        BaseInput = getDefaultImageName();
-      BaseInput =
-          C.getArgs().MakeArgString(std::string(BaseInput) + "-wrapper");
-    }
     Result = InputInfo(A, GetNamedOutputPath(C, *JA, BaseInput, BoundArch,
                                              AtTopLevel, MultipleArchs,
                                              OffloadingPrefix),

clang/lib/Driver/ToolChain.cpp

@@ -351,12 +351,6 @@ Tool *ToolChain::getOffloadBundler() const {
   return OffloadBundler.get();
 }
 
-Tool *ToolChain::getOffloadWrapper() const {
-  if (!OffloadWrapper)
-    OffloadWrapper.reset(new tools::OffloadWrapper(*this));
-  return OffloadWrapper.get();
-}
-
 Tool *ToolChain::getOffloadPackager() const {
   if (!OffloadPackager)
     OffloadPackager.reset(new tools::OffloadPackager(*this));
@@ -406,8 +400,6 @@ Tool *ToolChain::getTool(Action::ActionClass AC) const {
   case Action::OffloadUnbundlingJobClass:
     return getOffloadBundler();
 
-  case Action::OffloadWrapperJobClass:
-    return getOffloadWrapper();
   case Action::OffloadPackagerJobClass:
     return getOffloadPackager();
   case Action::LinkerWrapperJobClass: