[Driver][CUDA][OpenMP] Reimplement tool selection in the driver.

[sfantao]

Summary

This creates a tool selector in the driver that replaces the existing one. The goal is to better organize the code and make the selector easier to scale, in particular in the presence of offload actions that can be collapsed.

The current implementation became more confusing when the support for offloading actions was added. This concern was expressed by Eric in http://reviews.llvm.org/D9888.

This patch does not add new testing, it preserves the existing functionality.

[ABataev]

General comment: remove '\brief' tags, they are not required anymore, just '\\\' is enough

include/clang/Driver/Action.h

95

'\brief' tag is not required, remove it.

lib/Driver/Driver.cpp

2438

bool canCollapseAssembleAction() -> bool canCollapseAssembleAction() const

2446

Also can be marked as const

2454

I think this can be marked 'final' and add 'nullptr' as a default initializer for 'JA' field

2462

Remove '\brief'

2464

I think this function can be marked as 'static', no?

2473

remove '\brief'

[sfantao]

• Fix comments.
• Mark functions properly with const and static.
• Remove \brief.

[sfantao]

Hi Alexey,

Thanks for the review!

lib/Driver/Driver.cpp

2454

Yep, I'm doing that now.

2464

You're right, using static now.

[sfantao]

• Rebase

[sfantao]

• Rebase.

[sfantao]

• Rebase.

[sfantao]

• Rebase.

[ABataev]

LG for me

[hfinkel]

The naming here is a bit hard to follow, we have 'dependent action', 'dependency action', 'depending action', and I think they're all supposed to mean the same thing. Only 'dependent action' sounds right to me, can we use that universally (i.e. in all comments and names of functions and variables)?

lib/Driver/Driver.cpp

2402

As a micro-optimization, check CanBeCollapsed first, then call the function:

if (CanBeCollapsed && !CurAction->isCollapsingWithDependingActionLegal())

2416

if (CanBeCollapsed && !CurAction->isCollapsingWithDependingActionLegal())

2423

if (CanBeCollapsed && !CurAction->isCollapsingWithDependingActionLegal())

2454

Putting "Ty" on the end of a type name seems unusual for our code base (we generally use that for typedefs or for variables that represent types of other entities). Just JobActionInfo should be fine.

2484

I don't think we need 'attempt' in the name here, just make this:

combineAssembleBackendCompile

2515

combineBackendCompile

2516

We don't need 'attempt' in the name here either.

2536

combineWithPreprocessor

2603

action -> actions

2640

I don't think the syntactic regularity here is helpful enough to justify this extra if. Just do:

const Tool *T = combineAssembleBackendCompile(ActionChain, Inputs,
                                              CollapsedOffloadAction);

[sfantao]

• Address Hal Finkel suggestions - rename functions/reorder code/fix comments.

[sfantao]

Hi Hal,

Thanks for the review!

In D21840#555719, @hfinkel wrote:

The naming here is a bit hard to follow, we have 'dependent action', 'dependency action', 'depending action', and I think they're all supposed to mean the same thing. Only 'dependent action' sounds right to me, can we use that universally (i.e. in all comments and names of functions and variables)?

I agree the Depending/Dependence stuff can be confusing. However, I tried to use Depending and Dependence to indicate different things:

• Depending action -> an action that depends on the current one
• Dependence action -> an action that is a dependence to the current one

Of course they all are dependent actions, so your suggestion definitely makes sense. So, in the last diff I indicate:

• Depending action -> Next Dependent action
• Dependence action -> Prev(ious) Dependent action

I hope this helps clarifying things. Let me know you thoughts.

Thanks again!
Samuel

lib/Driver/Driver.cpp

2402

Ok, makes sense. Fixed this in the last diff.

2454

Ok, fixed that in the last diff.

2484

Ok, fixed in last diff.

2640

Ok, fixed in last diff.

[hfinkel]

LGTM

include/clang/Driver/Action.h

 private:
   ActionClass Kind;
 
   /// The output type of this action.
   types::ID Type;
 
   ActionList Inputs;
 
+  /// Flag that is set to true if this action can be collapsed with others
+  /// actions that depend on it. This is true by default and set to false when
+  /// the action is used by two different tool chains, which is enabled by the
+  /// offloading support implementation.
+  bool CanBeCollapsedWithNextDependentAction = true;
+
 protected:
   ///
   /// Offload information.
   ///
 
   /// The host offloading kind - a combination of kinds encoded in a mask.
   /// Multiple programming models may be supported simultaneously by the same
   /// host.
public:
   input_iterator input_end() { return Inputs.end(); }
   input_range inputs() { return input_range(input_begin(), input_end()); }
   input_const_iterator input_begin() const { return Inputs.begin(); }
   input_const_iterator input_end() const { return Inputs.end(); }
   input_const_range inputs() const {
     return input_const_range(input_begin(), input_end());
   }
 
+  /// Mark this action as not legal to collapse.
+  void setCannotBeCollapsedWithNextDependentAction() {
+    CanBeCollapsedWithNextDependentAction = false;
+  }
+  /// Return true if this function can be collapsed with others.
+  bool isCollapsingWithNextDependentActionLegal() const {
+    return CanBeCollapsedWithNextDependentAction;
+  }
+
   /// Return a string containing the offload kind of the action.
   std::string getOffloadingKindPrefix() const;
   /// Return a string that can be used as prefix in order to generate unique
   /// files for each offloading kind.
   std::string
   getOffloadingFileNamePrefix(llvm::StringRef NormalizedTriple) const;
 
   /// Set the device offload info of this action and propagate it to its

lib/Driver/Driver.cpp

if (DDeps.getActions().empty()) {
       // action it is assumed to depend on all actions generated so far.
       HostAction->propagateHostOffloadInfo(ActiveOffloadKinds,
                                            /*BoundArch=*/nullptr);
       return HostAction;
     }
 
     // Create the offload action with all dependences. When an offload action
     // is created the kinds are propagated to the host action, so we don't have
-    // to do that explicitely here.
+    // to do that explicitly here.
     OffloadAction::HostDependence HDep(
         *HostAction, *C.getSingleOffloadToolChain<Action::OFK_Host>(),
         /*BoundArch*/ nullptr, ActiveOffloadKinds);
     return C.MakeAction<OffloadAction>(HDep, DDeps);
   }
 };
 } // anonymous namespace.
 
if (!A->isClaimed()) {
       // In clang-cl, don't mention unknown arguments here since they have
       // already been warned about.
       if (!IsCLMode() || !A->getOption().matches(options::OPT_UNKNOWN))
         Diag(clang::diag::warn_drv_unused_argument)
             << A->getAsString(C.getArgs());
     }
   }
 }
-/// Collapse an offloading action looking for a job of the given type. The input
-/// action is changed to the input of the collapsed sequence. If we effectively
-/// had a collapse return the corresponding offloading action, otherwise return
-/// null.
-template <typename T>
-static OffloadAction *collapseOffloadingAction(Action *&CurAction) {
-  if (!CurAction)
+
+namespace {
+/// Utility class to control the collapse of dependent actions and select the
+/// tools accordingly.
+class ToolSelector final {
+  /// The tool chain this selector refers to.
+  const ToolChain &TC;
+
+  /// The compilation this selector refers to.
+  const Compilation &C;
+
+  /// The base action this selector refers to.
+  const JobAction *BaseAction;
+
+  /// Set to true if the current toolchain refers to host actions.
+  bool IsHostSelector;
+
+  /// Set to true if save-temps and embed-bitcode functionalities are active.
+  bool SaveTemps;
+  bool EmbedBitcode;
+
+  /// Get previous dependent action or null if that does not exist. If
+  /// \a CanBeCollapsed is false, that action must be legal to collapse or
+  /// null will be returned.
+  const JobAction *getPrevDependentAction(const ActionList &Inputs,
+                                          ActionList &SavedOffloadAction,
+                                          bool CanBeCollapsed = true) {
+    // An option can be collapsed only if it has a single input.
+    if (Inputs.size() != 1)
       return nullptr;
+
+    Action *CurAction = *Inputs.begin();
+    if (CanBeCollapsed &&
+        !CurAction->isCollapsingWithNextDependentActionLegal())
+      return nullptr;
+
+    // If the input action is an offload action. Look through it and save any
+    // offload action that can be dropped in the event of a collapse.
     if (auto *OA = dyn_cast<OffloadAction>(CurAction)) {
-    if (OA->hasHostDependence())
-      if (auto *HDep = dyn_cast<T>(OA->getHostDependence())) {
-        CurAction = HDep;
-        return OA;
-      }
-    if (OA->hasSingleDeviceDependence())
-      if (auto *DDep = dyn_cast<T>(OA->getSingleDeviceDependence())) {
-        CurAction = DDep;
-        return OA;
+      // If the dependent action is a device action, we will attempt to collapse
+      // only with other device actions. Otherwise, we would do the same but
+      // with host actions only.
+      if (!IsHostSelector) {
+        if (OA->hasSingleDeviceDependence(/*DoNotConsiderHostActions=*/true)) {
+          CurAction =
+              OA->getSingleDeviceDependence(/*DoNotConsiderHostActions=*/true);
+          if (CanBeCollapsed &&
+              !CurAction->isCollapsingWithNextDependentActionLegal())
+            return nullptr;
+          SavedOffloadAction.push_back(OA);
+          return dyn_cast<JobAction>(CurAction);
         }
+      } else if (OA->hasHostDependence()) {
+        CurAction = OA->getHostDependence();
+        if (CanBeCollapsed &&
+            !CurAction->isCollapsingWithNextDependentActionLegal())
+          return nullptr;
+        SavedOffloadAction.push_back(OA);
+        return dyn_cast<JobAction>(CurAction);
       }
       return nullptr;
     }
-// Returns a Tool for a given JobAction.  In case the action and its
-// predecessors can be combined, updates Inputs with the inputs of the
-// first combined action. If one of the collapsed actions is a
-// CudaHostAction, updates CollapsedCHA with the pointer to it so the
-// caller can deal with extra handling such action requires.
-static const Tool *selectToolForJob(Compilation &C, bool SaveTemps,
-                                    bool EmbedBitcode, const ToolChain *TC,
-                                    const JobAction *JA,
-                                    const ActionList *&Inputs,
-                                    ActionList &CollapsedOffloadAction) {
-  const Tool *ToolForJob = nullptr;
-  CollapsedOffloadAction.clear();
 
-  // See if we should look for a compiler with an integrated assembler. We match
-  // bottom up, so what we are actually looking for is an assembler job with a
-  // compiler input.
-
-  // Look through offload actions between assembler and backend actions.
-  Action *BackendJA = (isa<AssembleJobAction>(JA) && Inputs->size() == 1)
-                          ? *Inputs->begin()
-                          : nullptr;
-  auto *BackendOA = collapseOffloadingAction<BackendJobAction>(BackendJA);
+    return dyn_cast<JobAction>(CurAction);
+  }
 
-  if (TC->useIntegratedAs() && !SaveTemps &&
+  /// Return true if an assemble action can be collapsed.
+  bool canCollapseAssembleAction() const {
+    return TC.useIntegratedAs() && !SaveTemps &&
            !C.getArgs().hasArg(options::OPT_via_file_asm) &&
            !C.getArgs().hasArg(options::OPT__SLASH_FA) &&
-      !C.getArgs().hasArg(options::OPT__SLASH_Fa) && BackendJA &&
-      isa<BackendJobAction>(BackendJA)) {
-    // A BackendJob is always preceded by a CompileJob, and without -save-temps
-    // or -fembed-bitcode, they will always get combined together, so instead of
-    // checking the backend tool, check if the tool for the CompileJob has an
-    // integrated assembler. For -fembed-bitcode, CompileJob is still used to
-    // look up tools for BackendJob, but they need to match before we can split
-    // them.
-
-    // Look through offload actions between backend and compile actions.
-    Action *CompileJA = *BackendJA->getInputs().begin();
-    auto *CompileOA = collapseOffloadingAction<CompileJobAction>(CompileJA);
-
-    assert(CompileJA && isa<CompileJobAction>(CompileJA) &&
-           "Backend job is not preceeded by compile job.");
-    const Tool *Compiler = TC->SelectTool(*cast<CompileJobAction>(CompileJA));
-    if (!Compiler)
+           !C.getArgs().hasArg(options::OPT__SLASH_Fa);
+  }
+
+  /// Return true if a preprocessor action can be collapsed.
+  bool canCollapsePreprocessorAction() const {
+    return !C.getArgs().hasArg(options::OPT_no_integrated_cpp) &&
+           !C.getArgs().hasArg(options::OPT_traditional_cpp) && !SaveTemps &&
+           !C.getArgs().hasArg(options::OPT_rewrite_objc);
+  }
+
+  /// Struct that relates an action with the offload actions that would be
+  /// collapsed with it.
+  struct JobActionInfo final {
+    /// The action this info refers to.
+    const JobAction *JA = nullptr;
+    /// The offload actions we need to take care off if this action is
+    /// collapsed.
+    ActionList SavedOffloadAction;
+  };
+
+  /// Append collapsed offload actions from the give nnumber of elements in the
+  /// action info array.
+  static void AppendCollapsedOffloadAction(ActionList &CollapsedOffloadAction,
+                                           ArrayRef<JobActionInfo> &ActionInfo,
+                                           unsigned ElementNum) {
+    assert(ElementNum <= ActionInfo.size() && "Invalid number of elements.");
+    for (unsigned I = 0; I < ElementNum; ++I)
+      CollapsedOffloadAction.append(ActionInfo[I].SavedOffloadAction.begin(),
+                                    ActionInfo[I].SavedOffloadAction.end());
+  }
+
+  /// Functions that attempt to perform the combining. They detect if that is
+  /// legal, and if so they update the inputs \a Inputs and the offload action
+  /// that were collapsed in \a CollapsedOffloadAction. A tool that deals with
+  /// the combined action is returned. If the combining is not legal or if the
+  /// tool does not exist, null is returned.
+  /// Currently three kinds of collapsing are supported:
+  ///  - Assemble + Backend + Compile;
+  ///  - Assemble + Backend ;
+  ///  - Backend + Compile.
+  const Tool *
+  combineAssembleBackendCompile(ArrayRef<JobActionInfo> ActionInfo,
+                                const ActionList *&Inputs,
+                                ActionList &CollapsedOffloadAction) {
+    if (ActionInfo.size() < 3 || !canCollapseAssembleAction())
       return nullptr;
+    auto *AJ = dyn_cast<AssembleJobAction>(ActionInfo[0].JA);
+    auto *BJ = dyn_cast<BackendJobAction>(ActionInfo[1].JA);
+    auto *CJ = dyn_cast<CompileJobAction>(ActionInfo[2].JA);
+    if (!AJ || !BJ || !CJ)
+      return nullptr;
+
+    // Get compiler tool.
+    const Tool *T = TC.SelectTool(*CJ);
+    if (!T)
+      return nullptr;
+
     // When using -fembed-bitcode, it is required to have the same tool (clang)
     // for both CompilerJA and BackendJA. Otherwise, combine two stages.
     if (EmbedBitcode) {
-      JobAction *InputJA = cast<JobAction>(*Inputs->begin());
-      const Tool *BackendTool = TC->SelectTool(*InputJA);
-      if (BackendTool == Compiler)
-        CompileJA = InputJA;
-    }
-    if (Compiler->hasIntegratedAssembler()) {
-      Inputs = &CompileJA->getInputs();
-      ToolForJob = Compiler;
-      // Save the collapsed offload actions because they may still contain
-      // device actions.
-      if (CompileOA)
-        CollapsedOffloadAction.push_back(CompileOA);
-      if (BackendOA)
-        CollapsedOffloadAction.push_back(BackendOA);
+      const Tool *BT = TC.SelectTool(*BJ);
+      if (BT == T)
+        return nullptr;
     }
+
+    if (!T->hasIntegratedAssembler())
+      return nullptr;
+
+    Inputs = &CJ->getInputs();
+    AppendCollapsedOffloadAction(CollapsedOffloadAction, ActionInfo,
+                                 /*NumElements=*/3);
+    return T;
   }
+  const Tool *combineAssembleBackend(ArrayRef<JobActionInfo> ActionInfo,
+                                     const ActionList *&Inputs,
+                                     ActionList &CollapsedOffloadAction) {
+    if (ActionInfo.size() < 2 || !canCollapseAssembleAction())
+      return nullptr;
+    auto *AJ = dyn_cast<AssembleJobAction>(ActionInfo[0].JA);
+    auto *BJ = dyn_cast<BackendJobAction>(ActionInfo[1].JA);
+    if (!AJ || !BJ)
+      return nullptr;
+
+    // Retrieve the compile job, backend action must always be preceded by one.
+    ActionList CompileJobOffloadActions;
+    auto *CJ = getPrevDependentAction(BJ->getInputs(), CompileJobOffloadActions,
+                                      /*CanBeCollapsed=*/false);
+    if (!AJ || !BJ || !CJ)
+      return nullptr;
+
+    assert(isa<CompileJobAction>(CJ) &&
+           "Expecting compile job preceding backend job.");
+
+    // Get compiler tool.
+    const Tool *T = TC.SelectTool(*CJ);
+    if (!T)
+      return nullptr;
 
-  // A backend job should always be combined with the preceding compile job
-  // unless OPT_save_temps or OPT_fembed_bitcode is enabled and the compiler is
-  // capable of emitting LLVM IR as an intermediate output.
-  if (isa<BackendJobAction>(JA)) {
-    // Check if the compiler supports emitting LLVM IR.
-    assert(Inputs->size() == 1);
-
-    // Look through offload actions between backend and compile actions.
-    Action *CompileJA = *JA->getInputs().begin();
-    auto *CompileOA = collapseOffloadingAction<CompileJobAction>(CompileJA);
-
-    assert(CompileJA && isa<CompileJobAction>(CompileJA) &&
-           "Backend job is not preceeded by compile job.");
-    const Tool *Compiler = TC->SelectTool(*cast<CompileJobAction>(CompileJA));
-    if (!Compiler)
-      return nullptr;
-    if (!Compiler->canEmitIR() ||
-        (!SaveTemps && !EmbedBitcode)) {
-      Inputs = &CompileJA->getInputs();
-      ToolForJob = Compiler;
-
-      if (CompileOA)
-        CollapsedOffloadAction.push_back(CompileOA);
-    }
+    if (!T->hasIntegratedAssembler())
+      return nullptr;
+
+    Inputs = &BJ->getInputs();
+    AppendCollapsedOffloadAction(CollapsedOffloadAction, ActionInfo,
+                                 /*NumElements=*/2);
+    return T;
+  const Tool *combineBackendCompile(ArrayRef<JobActionInfo> ActionInfo,
+                                    const ActionList *&Inputs,
+                                    ActionList &CollapsedOffloadAction) {
+    if (ActionInfo.size() < 2 || !canCollapsePreprocessorAction())
+      return nullptr;
+    auto *BJ = dyn_cast<BackendJobAction>(ActionInfo[0].JA);
+    auto *CJ = dyn_cast<CompileJobAction>(ActionInfo[1].JA);
+    if (!BJ || !CJ)
+      return nullptr;
+
+    // Get compiler tool.
+    const Tool *T = TC.SelectTool(*CJ);
+    if (!T)
+      return nullptr;
+
+    if (T->canEmitIR() && (SaveTemps || EmbedBitcode))
+      return nullptr;
+
+    Inputs = &CJ->getInputs();
+    AppendCollapsedOffloadAction(CollapsedOffloadAction, ActionInfo,
+                                 /*NumElements=*/2);
+    return T;
   }
 
-  // Otherwise use the tool for the current job.
-  if (!ToolForJob)
-    ToolForJob = TC->SelectTool(*JA);
-
-  // See if we should use an integrated preprocessor. We do so when we have
-  // exactly one input, since this is the only use case we care about
-  // (irrelevant since we don't support combine yet).
-
-  // Look through offload actions after preprocessing.
-  Action *PreprocessJA = (Inputs->size() == 1) ? *Inputs->begin() : nullptr;
-  auto *PreprocessOA =
-      collapseOffloadingAction<PreprocessJobAction>(PreprocessJA);
+  /// Updates the inputs if the obtained tool supports combining with
+  /// preprocessor action, and the current input is indeed a preprocessor
+  /// action. If combining results in the collapse of offloading actions, those
+  /// are appended to \a CollapsedOffloadAction.
+  void combineWithPreprocessor(const Tool *T, const ActionList *&Inputs,
+                               ActionList &CollapsedOffloadAction) {
+    if (!T || !canCollapsePreprocessorAction() || !T->hasIntegratedCPP())
+      return;
 
-  if (PreprocessJA && isa<PreprocessJobAction>(PreprocessJA) &&
-      !C.getArgs().hasArg(options::OPT_no_integrated_cpp) &&
-      !C.getArgs().hasArg(options::OPT_traditional_cpp) && !SaveTemps &&
-      !C.getArgs().hasArg(options::OPT_rewrite_objc) &&
-      ToolForJob->hasIntegratedCPP()) {
-    Inputs = &PreprocessJA->getInputs();
-    if (PreprocessOA)
-      CollapsedOffloadAction.push_back(PreprocessOA);
+    // Attempt to get a preprocessor action dependence.
+    ActionList PreprocessJobOffloadActions;
+    auto *PJ = getPrevDependentAction(*Inputs, PreprocessJobOffloadActions);
+    if (!PJ || !isa<PreprocessJobAction>(PJ))
+      return;
+
+    // This is legal to combine. Append any offload action we found and set the
+    // current inputs to preprocessor inputs.
+    CollapsedOffloadAction.append(PreprocessJobOffloadActions.begin(),
+                                  PreprocessJobOffloadActions.end());
+    Inputs = &PJ->getInputs();
   }
 
-  return ToolForJob;
+public:
+  ToolSelector(const JobAction *BaseAction, const ToolChain &TC,
+               const Compilation &C, bool SaveTemps, bool EmbedBitcode)
+      : TC(TC), C(C), BaseAction(BaseAction), SaveTemps(SaveTemps),
+        EmbedBitcode(EmbedBitcode) {
+    assert(BaseAction && "Invalid base action.");
+    IsHostSelector = BaseAction->getOffloadingDeviceKind() == Action::OFK_None;
+  }
+
+  /// Check if a chain of actions can be combined and return the tool that can
+  /// handle the combination of actions. The pointer to the current inputs \a
+  /// Inputs and the list of offload actions \a CollapsedOffloadActions
+  /// connected to collapsed actions are updated accordingly. The latter enables
+  /// the caller of the selector to process them afterwards instead of just
+  /// dropping them. If no suitable tool is found, null will be returned.
+  const Tool *getTool(const ActionList *&Inputs,
+                      ActionList &CollapsedOffloadAction) {
+    //
+    // Get the largest chain of actions that we could combine.
+    //
+
+    SmallVector<JobActionInfo, 5> ActionChain(1);
+    ActionChain.back().JA = BaseAction;
+    while (ActionChain.back().JA) {
+      const Action *CurAction = ActionChain.back().JA;
+
+      // Grow the chain by one element.
+      ActionChain.resize(ActionChain.size() + 1);
+      JobActionInfo &AI = ActionChain.back();
+
+      // Attempt to fill it with the
+      AI.JA =
+          getPrevDependentAction(CurAction->getInputs(), AI.SavedOffloadAction);
+    }
+
+    // Pop the last action info as it could not be filled.
+    ActionChain.pop_back();
+
+    //
+    // Attempt to combine actions. If all combining attempts failed, just return
+    // the tool of the provided action. At the end we attempt to combine the
+    // action with any preprocessor action it may depend on.
+    //
+
+    const Tool *T = combineAssembleBackendCompile(ActionChain, Inputs,
+                                                  CollapsedOffloadAction);
+    if (!T)
+      T = combineAssembleBackend(ActionChain, Inputs, CollapsedOffloadAction);
+    if (!T)
+      T = combineBackendCompile(ActionChain, Inputs, CollapsedOffloadAction);
+    if (!T) {
+      Inputs = &BaseAction->getInputs();
+      T = TC.SelectTool(*BaseAction);
+    }
+
+    combineWithPreprocessor(T, Inputs, CollapsedOffloadAction);
+    return T;
+  }
+};
 }
 
 InputInfo Driver::BuildJobsForAction(
     Compilation &C, const Action *A, const ToolChain *TC, StringRef BoundArch,
     bool AtTopLevel, bool MultipleArchs, const char *LinkingOutput,
     std::map<std::pair<const Action *, std::string>, InputInfo> &CachedResults,
     bool BuildForOffloadDevice) const {
   // The bound arch is not necessarily represented in the toolchain's triple --
if (const OffloadAction *OA = dyn_cast<OffloadAction>(A)) {
     // The offload action is expected to be used in four different situations.
     //
     // a) Set a toolchain/architecture/kind for a host action:
     //    Host Action 1 -> OffloadAction -> Host Action 2
     //
     // b) Set a toolchain/architecture/kind for a device action;
     //    Device Action 1 -> OffloadAction -> Device Action 2
     //
-    // c) Specify a device dependences to a host action;
+    // c) Specify a device dependence to a host action;
     //    Device Action 1  _
     //                      \
     //      Host Action 1  ---> OffloadAction -> Host Action 2
     //
     // d) Specify a host dependence to a device action.
     //      Host Action 1  _
     //                      \
     //    Device Action 1  ---> OffloadAction -> Device Action 2
InputInfo Driver::BuildJobsForActionNoCache(
   }
 
 
   const ActionList *Inputs = &A->getInputs();
 
   const JobAction *JA = cast<JobAction>(A);
   ActionList CollapsedOffloadActions;
 
-  const Tool *T =
-      selectToolForJob(C, isSaveTempsEnabled(), embedBitcodeEnabled(), TC, JA,
-                       Inputs, CollapsedOffloadActions);
+  ToolSelector TS(JA, *TC, C, isSaveTempsEnabled(), embedBitcodeEnabled());
+  const Tool *T = TS.getTool(Inputs, CollapsedOffloadActions);
+
   if (!T)
     return InputInfo();
 
   // If we've collapsed action list that contained OffloadAction we
   // need to build jobs for host/device-side inputs it may have held.
   for (const auto *OA : CollapsedOffloadActions)
     cast<OffloadAction>(OA)->doOnEachDependence(
         /*IsHostDependence=*/BuildForOffloadDevice,