[OMPIRBuilder] Support depend clause for task construct

[psoni2628]

Summary

This patch adds OMPIRBuilder support for the depend clause for the
task construct.

[tschuett]

llvm/include/llvm/Frontend/OpenMP/OMPConstants.h

210

The enums above are enum class.

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

648

Why is this not enum class?

[psoni2628]

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

649

There is some code duplication going on here. For example, this enum is basically copied from clang/include/clang/Basic/OpenMPKinds.def. I tried extracting this enum into llvm/include/llvm/Frontend/OpenMP/OMPConstants.h so that Clang can use it, but it seems that the OPENMP_DEPEND_KIND macro is complex and does not lend itself to a simple extraction. The macro is redefined in many different files. Any suggestions here would be appreciated.

[psoni2628]

• Use enum class instead of enum for OpenMPDependKind and OMPRTLDependenceKindTy

[psoni2628]

• Rebase, run clang-format

[domada]

llvm/include/llvm/Frontend/OpenMP/OMPConstants.h

210

Do we need definition of OMPRTLDependenceKindTy and OpenMPDependKind ? It looks like these two class enums are overlapping.

[psoni2628]

llvm/include/llvm/Frontend/OpenMP/OMPConstants.h

210

OMPRTLDependenceKindTy is to be used with the OMPRTL___kmpc_omp_task_with_deps runtime function to encode what kind of dependency a given clause is, whereas OpenMPDependKind is for the MLIR to encode what kind of dependency a given clause is. You could map them to the same thing, but IMO, it is better to keep them separate. llvm::OpenMPIRBuilder::OpenMPDependKind::OMP_DEPEND_out and llvm::OpenMPIRBuilder::OpenMPDependKind::OMP_DEPEND_inout happen to map to the same thing, OMPRTLDependenceKindTy::OMPDepInOut, which is what the translateDependencyKind function does, but I don't think it makes much sense to map them to the same thing at the MLIR level. IMO, they should be kept distinct.

[jdoerfert]

llvm/include/llvm/Frontend/OpenMP/OMPConstants.h

210

I doubt we want duplication. It doesn't buy as anything and introduces confusion.

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

649

I don't understand the problem. Define all depend kinds similar to proc bind here https://github.com/llvm/llvm-project/blob/25162418c60475185cf29b5336015ca2f52ce3eb/llvm/include/llvm/Frontend/OpenMP/OMPKinds.def#L1052 . Then use that to create the enum class in OMPConstants.h and use that enum class as well as the macro everywhere, including clang.

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1521

Is the insert point set to the right place for sure?

1556

Generally, llvm:: inside llvm/ if we open the namespace anyway.

[psoni2628]

• Remove unnecessary llvm:: from OMPIRBuilder.cpp
• Change the insertion point for DepArray alloca to be before the Then basic block for the if clause
• Use only one enum RTLDependenceKindInfoTy to encode the kind of dependency; use this enum in Clang

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

649

Thanks for the suggestion! However, if we don't want to have 2 enums, one for the clause and one for the RTL function, as you mentioned in one of your other comments (quoted below), then I can just define a singular enum in OMPConstants.h. IMO, this is simpler.

I doubt we want duplication. It doesn't buy as anything and introduces confusion.

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1521

Looking more closely at it, I think this should be inserted before the Then of the IfThenElse for the if clause, but then the OMPRTL___kmpc_omp_task_with_deps call should still be in the Then.

[jdoerfert]

Generally fine, I think. The alloca placement is the last bit that needs changing.

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

649

If these are all uses, I assume a fixed enum is good enough.

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1441

Same question as before. How do you ensure the alloca is placed where you want it (which is the function entry block).

1521

The entire conditional here is a bad idea. We should pass the if-clause value to the runtime. This causes all sort of problems, but it's unrelated to this patch...

[psoni2628]

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1441

Isn't the insertion point set on L1356 in OMPIRBuilder.cpp at the caller of the outlined function, i.e. the outlined function entry block? I thought it made sense to do the alloca in this same block, right after the __kmpc_omp_task_alloc. If not this one, which function entry block are you suggesting I should place the alloca in?

[jdoerfert]

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1441

Reading L1356, it looks like it is set to the call site of outlined function, which could be anywhere in current function, no? Allocas that only need to provide a single memory location for each function invocation should be placed in the function entry block.

[psoni2628]

• Set insertion point for DependInfo array alloca to the function entry block, then restore the original insertion point

[psoni2628]

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

1441

That makes sense. Thanks for the clarification.

[jdoerfert]

LG, one nit.

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

656

Add doxygen documentation for this class please.

[psoni2628]

• Add doxygen comment for DependData struct

clang/lib/CodeGen/CGOpenMPRuntime.cpp

CGOpenMPRuntime::emitTaskInit(CodeGenFunction &CGF, SourceLocation Loc,
   Result.NewTask = NewTask;
   Result.TaskEntry = TaskEntry;
   Result.NewTaskNewTaskTTy = NewTaskNewTaskTTy;
   Result.TDBase = TDBase;
   Result.KmpTaskTQTyRD = KmpTaskTQTyRD;
   return Result;
 }
 
-namespace {
-/// Dependence kind for RTL.
-enum RTLDependenceKindTy {
-  DepIn = 0x01,
-  DepInOut = 0x3,
-  DepMutexInOutSet = 0x4,
-  DepInOutSet = 0x8,
-  DepOmpAllMem = 0x80,
-};
-/// Fields ids in kmp_depend_info record.
-enum RTLDependInfoFieldsTy { BaseAddr, Len, Flags };
-} // namespace
-
 /// Translates internal dependency kind into the runtime kind.
 static RTLDependenceKindTy translateDependencyKind(OpenMPDependClauseKind K) {
   RTLDependenceKindTy DepKind;
   switch (K) {
   case OMPC_DEPEND_in:
-    DepKind = DepIn;
+    DepKind = RTLDependenceKindTy::DepIn;
     break;
   // Out and InOut dependencies must use the same code.
   case OMPC_DEPEND_out:
   case OMPC_DEPEND_inout:
-    DepKind = DepInOut;
+    DepKind = RTLDependenceKindTy::DepInOut;
     break;
   case OMPC_DEPEND_mutexinoutset:
-    DepKind = DepMutexInOutSet;
+    DepKind = RTLDependenceKindTy::DepMutexInOutSet;
     break;
   case OMPC_DEPEND_inoutset:
-    DepKind = DepInOutSet;
+    DepKind = RTLDependenceKindTy::DepInOutSet;
     break;
   case OMPC_DEPEND_outallmemory:
-    DepKind = DepOmpAllMem;
+    DepKind = RTLDependenceKindTy::DepOmpAllMem;
     break;
   case OMPC_DEPEND_source:
   case OMPC_DEPEND_sink:
   case OMPC_DEPEND_depobj:
   case OMPC_DEPEND_inoutallmemory:
   case OMPC_DEPEND_unknown:
     llvm_unreachable("Unknown task dependence type");
   }
LValue Base = CGF.EmitLoadOfPointerLValue(
       KmpDependInfoPtrTy->castAs<PointerType>());
   Address DepObjAddr = CGF.Builder.CreateGEP(
       Base.getAddress(CGF),
       llvm::ConstantInt::get(CGF.IntPtrTy, -1, /*isSigned=*/true));
   LValue NumDepsBase = CGF.MakeAddrLValue(
       DepObjAddr, KmpDependInfoTy, Base.getBaseInfo(), Base.getTBAAInfo());
   // NumDeps = deps[i].base_addr;
   LValue BaseAddrLVal = CGF.EmitLValueForField(
-      NumDepsBase, *std::next(KmpDependInfoRD->field_begin(), BaseAddr));
+      NumDepsBase,
+      *std::next(KmpDependInfoRD->field_begin(),
+                 static_cast<unsigned int>(RTLDependInfoFields::BaseAddr)));
   llvm::Value *NumDeps = CGF.EmitLoadOfScalar(BaseAddrLVal, Loc);
   return std::make_pair(NumDeps, Base);
 }
 
 static void emitDependData(CodeGenFunction &CGF, QualType &KmpDependInfoTy,
                            llvm::PointerUnion<unsigned *, LValue *> Pos,
                            const OMPTaskDataTy::DependData &Data,
                            Address DependenciesArray) {
if (unsigned *P = Pos.dyn_cast<unsigned *>()) {
       assert(E && "Expected a non-null expression");
       LValue &PosLVal = *Pos.get<LValue *>();
       llvm::Value *Idx = CGF.EmitLoadOfScalar(PosLVal, E->getExprLoc());
       Base = CGF.MakeAddrLValue(
           CGF.Builder.CreateGEP(DependenciesArray, Idx), KmpDependInfoTy);
     }
     // deps[i].base_addr = &<Dependencies[i].second>;
     LValue BaseAddrLVal = CGF.EmitLValueForField(
-        Base, *std::next(KmpDependInfoRD->field_begin(), BaseAddr));
+        Base,
+        *std::next(KmpDependInfoRD->field_begin(),
+                   static_cast<unsigned int>(RTLDependInfoFields::BaseAddr)));
     CGF.EmitStoreOfScalar(Addr, BaseAddrLVal);
     // deps[i].len = sizeof(<Dependencies[i].second>);
     LValue LenLVal = CGF.EmitLValueForField(
-        Base, *std::next(KmpDependInfoRD->field_begin(), Len));
+        Base, *std::next(KmpDependInfoRD->field_begin(),
+                         static_cast<unsigned int>(RTLDependInfoFields::Len)));
     CGF.EmitStoreOfScalar(Size, LenLVal);
     // deps[i].flags = <Dependencies[i].first>;
     RTLDependenceKindTy DepKind = translateDependencyKind(Data.DepKind);
     LValue FlagsLVal = CGF.EmitLValueForField(
-        Base, *std::next(KmpDependInfoRD->field_begin(), Flags));
-    CGF.EmitStoreOfScalar(llvm::ConstantInt::get(LLVMFlagsTy, DepKind),
-                          FlagsLVal);
+        Base,
+        *std::next(KmpDependInfoRD->field_begin(),
+                   static_cast<unsigned int>(RTLDependInfoFields::Flags)));
+    CGF.EmitStoreOfScalar(
+        llvm::ConstantInt::get(LLVMFlagsTy, static_cast<unsigned int>(DepKind)),
     if (unsigned *P = Pos.dyn_cast<unsigned *>()) {
       ++(*P);
     } else {
       LValue &PosLVal = *Pos.get<LValue *>();
       llvm::Value *Idx = CGF.EmitLoadOfScalar(PosLVal, E->getExprLoc());
       Idx = CGF.Builder.CreateNUWAdd(Idx,
                                      llvm::ConstantInt::get(Idx->getType(), 1));
       CGF.EmitStoreOfScalar(Idx, PosLVal);
Address CGOpenMPRuntime::emitDepobjDependClause(
   llvm::Type *KmpDependInfoLlvmTy = CGF.ConvertTypeForMem(KmpDependInfoTy);
   Addr = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
       Addr, KmpDependInfoLlvmTy->getPointerTo());
   DependenciesArray = Address(Addr, KmpDependInfoLlvmTy, Align);
   // Write number of elements in the first element of array for depobj.
   LValue Base = CGF.MakeAddrLValue(DependenciesArray, KmpDependInfoTy);
   // deps[i].base_addr = NumDependencies;
   LValue BaseAddrLVal = CGF.EmitLValueForField(
-      Base, *std::next(KmpDependInfoRD->field_begin(), BaseAddr));
+      Base,
+      *std::next(KmpDependInfoRD->field_begin(),
+                 static_cast<unsigned int>(RTLDependInfoFields::BaseAddr)));
   CGF.EmitStoreOfScalar(NumDepsVal, BaseAddrLVal);
   llvm::PointerUnion<unsigned *, LValue *> Pos;
   unsigned Idx = 1;
   LValue PosLVal;
   if (Dependencies.IteratorExpr) {
     PosLVal = CGF.MakeAddrLValue(
         CGF.CreateMemTemp(C.getSizeType(), "iterator.counter.addr"),
         C.getSizeType());
llvm::PHINode *ElementPHI =
       CGF.Builder.CreatePHI(Begin.getType(), 2, "omp.elementPast");
   ElementPHI->addIncoming(Begin.getPointer(), EntryBB);
   Begin = Begin.withPointer(ElementPHI);
   Base = CGF.MakeAddrLValue(Begin, KmpDependInfoTy, Base.getBaseInfo(),
                             Base.getTBAAInfo());
   // deps[i].flags = NewDepKind;
   RTLDependenceKindTy DepKind = translateDependencyKind(NewDepKind);
   LValue FlagsLVal = CGF.EmitLValueForField(
-      Base, *std::next(KmpDependInfoRD->field_begin(), Flags));
-  CGF.EmitStoreOfScalar(llvm::ConstantInt::get(LLVMFlagsTy, DepKind),
-                        FlagsLVal);
+      Base, *std::next(KmpDependInfoRD->field_begin(),
+                       static_cast<unsigned int>(RTLDependInfoFields::Flags)));
+  CGF.EmitStoreOfScalar(
+      llvm::ConstantInt::get(LLVMFlagsTy, static_cast<unsigned int>(DepKind)),
 
   // Shift the address forward by one element.
   Address ElementNext =
       CGF.Builder.CreateConstGEP(Begin, /*Index=*/1, "omp.elementNext");
   ElementPHI->addIncoming(ElementNext.getPointer(),
                           CGF.Builder.GetInsertBlock());
   llvm::Value *IsEmpty =
       CGF.Builder.CreateICmpEQ(ElementNext.getPointer(), End, "omp.isempty");

llvm/include/llvm/Frontend/OpenMP/OMPConstants.h

 };
 
 /// \note This needs to be kept in sync with interop.h enum kmp_interop_type_t.:
 enum class OMPInteropType { Unknown, Target, TargetSync };
 
 /// Atomic compare operations. Currently OpenMP only supports ==, >, and <.
 enum class OMPAtomicCompareOp : unsigned { EQ, MIN, MAX };
 
+/// Fields ids in kmp_depend_info record.
+enum class RTLDependInfoFields { BaseAddr, Len, Flags };
+
+/// Dependence kind for RTL.
+enum class RTLDependenceKindTy {
+  DepUnknown = 0x0,
+  DepIn = 0x01,
+  DepInOut = 0x3,
+  DepMutexInOutSet = 0x4,
+  DepInOutSet = 0x8,
+  DepOmpAllMem = 0x80,
+};
+
 } // end namespace omp
 
 } // end namespace llvm
 
 #endif // LLVM_FRONTEND_OPENMP_OMPCONSTANTS_H

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

public:
   /// \param Loc The location where the taskwait directive was encountered.
   void createTaskwait(const LocationDescription &Loc);
 
   /// Generator for '#omp taskyield'
   ///
   /// \param Loc The location where the taskyield directive was encountered.
   void createTaskyield(const LocationDescription &Loc);
 
+  /// A struct to pack the relevant information for an OpenMP depend clause.
+  struct DependData {
+    omp::RTLDependenceKindTy DepKind = omp::RTLDependenceKindTy::DepUnknown;
+    Type *DepValueType;
+    Value *DepVal;
+    explicit DependData() = default;
+    DependData(omp::RTLDependenceKindTy DepKind, Type *DepValueType,
+               Value *DepVal)
+        : DepKind(DepKind), DepValueType(DepValueType), DepVal(DepVal) {}
+  };
+
   /// Generator for `#omp task`
   ///
   /// \param Loc The location where the task construct was encountered.
   /// \param AllocaIP The insertion point to be used for alloca instructions.
   /// \param BodyGenCB Callback that will generate the region code.
   /// \param Tied True if the task is tied, false if the task is untied.
   /// \param Final i1 value which is `true` if the task is final, `false` if the
   ///              task is not final.
   /// \param IfCondition i1 value. If it evaluates to `false`, an undeferred
   ///                    task is generated, and the encountering thread must
   ///                    suspend the current task region, for which execution
   ///                    cannot be resumed until execution of the structured
   ///                    block that is associated with the generated task is
   ///                    completed.
   InsertPointTy createTask(const LocationDescription &Loc,
                            InsertPointTy AllocaIP, BodyGenCallbackTy BodyGenCB,
                            bool Tied = true, Value *Final = nullptr,
-                           Value *IfCondition = nullptr);
+                           Value *IfCondition = nullptr,
+                           ArrayRef<DependData *> Dependencies = {});
 
   /// Generator for the taskgroup construct
   ///
   /// \param Loc The location where the taskgroup construct was encountered.
   /// \param AllocaIP The insertion point to be used for alloca instructions.
   /// \param BodyGenCB Callback that will generate the region code.
   InsertPointTy createTaskgroup(const LocationDescription &Loc,
                                 InsertPointTy AllocaIP,

llvm/include/llvm/Frontend/OpenMP/OMPKinds.def

#define __OMP_STRUCT_TYPE(VarName, Name, ...)                                  \
   OMP_STRUCT_TYPE(VarName, "struct." #Name, __VA_ARGS__)
 
 __OMP_STRUCT_TYPE(Ident, ident_t, Int32, Int32, Int32, Int32, Int8Ptr)
 __OMP_STRUCT_TYPE(OffloadEntry, __tgt_offload_entry, Int8Ptr, Int8Ptr, SizeTy,
                   Int32, Int32)
 __OMP_STRUCT_TYPE(KernelArgs, __tgt_kernel_arguments, Int32, Int32, VoidPtrPtr,
                   VoidPtrPtr, Int64Ptr, Int64Ptr, VoidPtrPtr, VoidPtrPtr, Int64)
 __OMP_STRUCT_TYPE(AsyncInfo, __tgt_async_info, Int8Ptr)
+__OMP_STRUCT_TYPE(DependInfo, kmp_dep_info, SizeTy, SizeTy, Int8)
 
 #undef __OMP_STRUCT_TYPE
 #undef OMP_STRUCT_TYPE
 
 #ifndef OMP_FUNCTION_TYPE
 #define OMP_FUNCTION_TYPE(VarName, IsVarArg, ReturnType, ...)
 #endif
 

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

void OpenMPIRBuilder::createTaskyield(const LocationDescription &Loc) {
   if (!updateToLocation(Loc))
     return;
   emitTaskyieldImpl(Loc);
 }
 
 OpenMPIRBuilder::InsertPointTy
 OpenMPIRBuilder::createTask(const LocationDescription &Loc,
                             InsertPointTy AllocaIP, BodyGenCallbackTy BodyGenCB,
-                            bool Tied, Value *Final, Value *IfCondition) {
+                            bool Tied, Value *Final, Value *IfCondition,
+                            ArrayRef<DependData *> Dependencies) {
   if (!updateToLocation(Loc))
     return InsertPointTy();
 
   uint32_t SrcLocStrSize;
   Constant *SrcLocStr = getOrCreateSrcLocStr(Loc, SrcLocStrSize);
   Value *Ident = getOrCreateIdent(SrcLocStr, SrcLocStrSize);
   // The current basic block is split into four basic blocks. After outlining,
   // they will be mapped as follows:
OpenMPIRBuilder::createTask(const LocationDescription &Loc,
   BasicBlock *TaskBodyBB = splitBB(Builder, /*CreateBranch=*/true, "task.body");
   BasicBlock *TaskAllocaBB =
       splitBB(Builder, /*CreateBranch=*/true, "task.alloca");
 
   OutlineInfo OI;
   OI.EntryBB = TaskAllocaBB;
   OI.OuterAllocaBB = AllocaIP.getBlock();
   OI.ExitBB = TaskExitBB;
-  OI.PostOutlineCB = [this, Ident, Tied, Final,
-                      IfCondition](Function &OutlinedFn) {
+  OI.PostOutlineCB = [this, Ident, Tied, Final, IfCondition,
+                      Dependencies](Function &OutlinedFn) {
     // The input IR here looks like the following-
     // ```
     // func @current_fn() {
     //   outlined_fn(%args)
     // }
     // func @outlined_fn(%args) { ... }
     // ```
     //
OI.PostOutlineCB = [this, Ident, Tied, Final, IfCondition,
     // Copy the arguments for outlined function
     if (HasTaskData) {
       Value *TaskData = StaleCI->getArgOperand(0);
       Align Alignment = TaskData->getPointerAlignment(M.getDataLayout());
       Builder.CreateMemCpy(NewTaskData, Alignment, TaskData, Alignment,
                            TaskSize);
     }
 
+    Value *DepArrayPtr = nullptr;
+    if (Dependencies.size()) {
+      InsertPointTy OldIP = Builder.saveIP();
+      Builder.SetInsertPoint(
+          &OldIP.getBlock()->getParent()->getEntryBlock().back());
+
+      Type *DepArrayTy = ArrayType::get(DependInfo, Dependencies.size());
+      Value *DepArray =
+          Builder.CreateAlloca(DepArrayTy, nullptr, ".dep.arr.addr");
+
+      unsigned P = 0;
+      for (DependData *Dep : Dependencies) {
+        Value *Base =
+            Builder.CreateConstInBoundsGEP2_64(DepArrayTy, DepArray, 0, P);
+        // Store the pointer to the variable
+        Value *Addr = Builder.CreateStructGEP(
+            DependInfo, Base,
+            static_cast<unsigned int>(RTLDependInfoFields::BaseAddr));
+        Value *DepValPtr =
+            Builder.CreatePtrToInt(Dep->DepVal, Builder.getInt64Ty());
+        Builder.CreateStore(DepValPtr, Addr);
+        // Store the size of the variable
+        Value *Size = Builder.CreateStructGEP(
+            DependInfo, Base,
+            static_cast<unsigned int>(RTLDependInfoFields::Len));
+        Builder.CreateStore(Builder.getInt64(M.getDataLayout().getTypeStoreSize(
+                                Dep->DepValueType)),
+                            Size);
+        // Store the dependency kind
+        Value *Flags = Builder.CreateStructGEP(
+            DependInfo, Base,
+            static_cast<unsigned int>(RTLDependInfoFields::Flags));
+        Builder.CreateStore(
+            ConstantInt::get(Builder.getInt8Ty(),
+                             static_cast<unsigned int>(Dep->DepKind)),
+            Flags);
+        ++P;
+      }
+
+      DepArrayPtr = Builder.CreateBitCast(DepArray, Builder.getInt8PtrTy());
+      Builder.restoreIP(OldIP);
+    }
+
     // In the presence of the `if` clause, the following IR is generated:
     //    ...
     //    %data = call @__kmpc_omp_task_alloc(...)
     //    br i1 %if_condition, label %then, label %else
     //  then:
     //    call @__kmpc_omp_task(...)
     //    br label %exit
     //  else:
if (IfCondition) {
       Builder.CreateCall(TaskBeginFn, {Ident, ThreadID, NewTaskData});
       if (HasTaskData)
         Builder.CreateCall(WrapperFunc, {ThreadID, NewTaskData});
       else
         Builder.CreateCall(WrapperFunc, {ThreadID});
       Builder.CreateCall(TaskCompleteFn, {Ident, ThreadID, NewTaskData});
       Builder.SetInsertPoint(ThenTI);
     }
+
+    if (Dependencies.size()) {
+      Function *TaskFn =
+          getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task_with_deps);
+      Builder.CreateCall(
+          TaskFn,
+          {Ident, ThreadID, NewTaskData, Builder.getInt32(Dependencies.size()),
+           DepArrayPtr, ConstantInt::get(Builder.getInt32Ty(), 0),
+           ConstantPointerNull::get(Type::getInt8PtrTy(M.getContext()))});
+
+    } else {
       // Emit the @__kmpc_omp_task runtime call to spawn the task
       Function *TaskFn = getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task);
       Builder.CreateCall(TaskFn, {Ident, ThreadID, NewTaskData});
+    }
 
     StaleCI->eraseFromParent();
 
     // Emit the body for wrapper function
     BasicBlock *WrapperEntryBB =
         BasicBlock::Create(M.getContext(), "", WrapperFunc);
     Builder.SetInsertPoint(WrapperEntryBB);
     if (HasTaskData)
       Builder.CreateCall(&OutlinedFn, {WrapperFunc->getArg(1)});
     else
       Builder.CreateCall(&OutlinedFn);
     Builder.CreateRet(Builder.getInt32(0));
   };
 
   addOutlineInfo(std::move(OI));
 
   InsertPointTy TaskAllocaIP =
       InsertPointTy(TaskAllocaBB, TaskAllocaBB->begin());
   InsertPointTy TaskBodyIP = InsertPointTy(TaskBodyBB, TaskBodyBB->begin());
   BodyGenCB(TaskAllocaIP, TaskBodyIP);
   Builder.SetInsertPoint(TaskExitBB, TaskExitBB->begin());
 
   return Builder.saveIP();
 }
 
 OpenMPIRBuilder::InsertPointTy
 OpenMPIRBuilder::createTaskgroup(const LocationDescription &Loc,
                                  InsertPointTy AllocaIP,
                                  BodyGenCallbackTy BodyGenCB) {
   if (!updateToLocation(Loc))
     return InsertPointTy();
 

llvm/unittests/Frontend/OpenMPIRBuilderTest.cpp

TEST_F(OpenMPIRBuilderTest, CreateTaskUntied) {
   ASSERT_NE(TaskAllocCall, nullptr);
   ConstantInt *Flags = dyn_cast<ConstantInt>(TaskAllocCall->getArgOperand(2));
   ASSERT_NE(Flags, nullptr);
   EXPECT_EQ(Flags->getZExtValue() & 1U, 0U);
 
   EXPECT_FALSE(verifyModule(*M, &errs()));
 }
 
+TEST_F(OpenMPIRBuilderTest, CreateTaskDepend) {
+  using InsertPointTy = OpenMPIRBuilder::InsertPointTy;
+  OpenMPIRBuilder OMPBuilder(*M);
+  OMPBuilder.initialize();
+  F->setName("func");
+  IRBuilder<> Builder(BB);
+  auto BodyGenCB = [&](InsertPointTy AllocaIP, InsertPointTy CodeGenIP) {};
+  BasicBlock *AllocaBB = Builder.GetInsertBlock();
+  BasicBlock *BodyBB = splitBB(Builder, /*CreateBranch=*/true, "alloca.split");
+  OpenMPIRBuilder::LocationDescription Loc(
+      InsertPointTy(BodyBB, BodyBB->getFirstInsertionPt()), DL);
+  AllocaInst *InDep = Builder.CreateAlloca(Type::getInt32Ty(M->getContext()));
+  OpenMPIRBuilder::DependData DDIn(RTLDependenceKindTy::DepIn,
+                                   Type::getInt32Ty(M->getContext()), InDep);
+  SmallVector<OpenMPIRBuilder::DependData *, 4> DDS;
+  DDS.push_back(&DDIn);
+  Builder.restoreIP(OMPBuilder.createTask(
+      Loc, InsertPointTy(AllocaBB, AllocaBB->getFirstInsertionPt()), BodyGenCB,
+      /*Tied=*/false, /*Final*/ nullptr, /*IfCondition*/ nullptr, DDS));
+  OMPBuilder.finalize();
+  Builder.CreateRetVoid();
+
+  // Check for the `NumDeps` argument
+  CallInst *TaskAllocCall = dyn_cast<CallInst>(
+      OMPBuilder
+          .getOrCreateRuntimeFunctionPtr(OMPRTL___kmpc_omp_task_with_deps)
+          ->user_back());
+  ASSERT_NE(TaskAllocCall, nullptr);
+  ConstantInt *NumDeps = dyn_cast<ConstantInt>(TaskAllocCall->getArgOperand(3));
+  ASSERT_NE(NumDeps, nullptr);
+  EXPECT_EQ(NumDeps->getZExtValue(), 1U);
+
+  // Check for the `DepInfo` array argument
+  BitCastInst *DepArrayPtr =
+      dyn_cast<BitCastInst>(TaskAllocCall->getOperand(4));
+  ASSERT_NE(DepArrayPtr, nullptr);
+  AllocaInst *DepArray = dyn_cast<AllocaInst>(DepArrayPtr->getOperand(0));
+  ASSERT_NE(DepArray, nullptr);
+  Value::user_iterator DepArrayI = DepArray->user_begin();
+  EXPECT_EQ(*DepArrayI, DepArrayPtr);
+  ++DepArrayI;
+  Value::user_iterator DepInfoI = DepArrayI->user_begin();
+  // Check for the `DependKind` flag in the `DepInfo` array
+  Value *Flag = findStoredValue<GetElementPtrInst>(*DepInfoI);
+  ASSERT_NE(Flag, nullptr);
+  ConstantInt *FlagInt = dyn_cast<ConstantInt>(Flag);
+  ASSERT_NE(FlagInt, nullptr);
+  EXPECT_EQ(FlagInt->getZExtValue(),
+            static_cast<unsigned int>(RTLDependenceKindTy::DepIn));
+  ++DepInfoI;
+  // Check for the size in the `DepInfo` array
+  Value *Size = findStoredValue<GetElementPtrInst>(*DepInfoI);
+  ASSERT_NE(Size, nullptr);
+  ConstantInt *SizeInt = dyn_cast<ConstantInt>(Size);
+  ASSERT_NE(SizeInt, nullptr);
+  EXPECT_EQ(SizeInt->getZExtValue(), 4U);
+  ++DepInfoI;
+  // Check for the variable address in the `DepInfo` array
+  Value *AddrStored = findStoredValue<GetElementPtrInst>(*DepInfoI);
+  ASSERT_NE(AddrStored, nullptr);
+  PtrToIntInst *AddrInt = dyn_cast<PtrToIntInst>(AddrStored);
+  ASSERT_NE(AddrInt, nullptr);
+  Value *Addr = AddrInt->getPointerOperand();
+  EXPECT_EQ(Addr, InDep);
+
+  ConstantInt *NumDepsNoAlias =
+      dyn_cast<ConstantInt>(TaskAllocCall->getArgOperand(5));
+  ASSERT_NE(NumDepsNoAlias, nullptr);
+  EXPECT_EQ(NumDepsNoAlias->getZExtValue(), 0U);
+  EXPECT_EQ(TaskAllocCall->getOperand(6),
+            ConstantPointerNull::get(Type::getInt8PtrTy(M->getContext())));
+
+  EXPECT_FALSE(verifyModule(*M, &errs()));
+}
+
 TEST_F(OpenMPIRBuilderTest, CreateTaskFinal) {
   using InsertPointTy = OpenMPIRBuilder::InsertPointTy;
   OpenMPIRBuilder OMPBuilder(*M);
   OMPBuilder.initialize();
   F->setName("func");
   IRBuilder<> Builder(BB);
   auto BodyGenCB = [&](InsertPointTy AllocaIP, InsertPointTy CodeGenIP) {};
   IRBuilderBase::InsertPoint AllocaIP = Builder.saveIP();