[OpenMP] Introduce the initial support for OpenMP kernel language

clang/include/clang/AST/OpenMPClause.h

@@ -9220,6 +9220,27 @@ class OMPXAttributeClause
   }
 };
 
+/// This represents 'ompx_bare' clause in the '#pragma omp target teams ...'
+/// directive.
+///
+/// \code
+/// #pragma omp target teams ompx_bare
+/// \endcode
+/// In this example directive '#pragma omp target teams' has a 'ompx_bare'
+/// clause.
+class OMPXBareClause : public OMPNoChildClause<llvm::omp::OMPC_ompx_bare> {
+public:
+  /// Build 'ompx_bare' clause.
+  ///
+  /// \param StartLoc Starting location of the clause.
+  /// \param EndLoc Ending location of the clause.
+  OMPXBareClause(SourceLocation StartLoc, SourceLocation EndLoc)
+      : OMPNoChildClause(StartLoc, EndLoc) {}
+
+  /// Build an empty clause.
+  OMPXBareClause() = default;
+};
+
 } // namespace clang
 
 #endif // LLVM_CLANG_AST_OPENMPCLAUSE_H

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -3890,6 +3890,11 @@ bool RecursiveASTVisitor<Derived>::VisitOMPXAttributeClause(
   return true;
 }
 
+template <typename Derived>
+bool RecursiveASTVisitor<Derived>::VisitOMPXBareClause(OMPXBareClause *C) {
+  return true;
+}
+
 // FIXME: look at the following tricky-seeming exprs to see if we
 // need to recurse on anything.  These are ones that have methods
 // returning decls or qualtypes or nestednamespecifier -- though I'm

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1360,6 +1360,8 @@ def warn_clause_expected_string : Warning<
   "expected string literal in 'clause %0' - ignoring">, InGroup<IgnoredPragmas>;
 def err_omp_unexpected_clause : Error<
   "unexpected OpenMP clause '%0' in directive '#pragma omp %1'">;
+def err_omp_unexpected_clause_extension_only : Error<
+  "OpenMP clause '%0' is only available as extension, use '-fopenmp-extensions'">;
 def err_omp_immediate_directive : Error<
   "'#pragma omp %0' %select{|with '%2' clause }1cannot be an immediate substatement">;
 def err_omp_expected_identifier_for_critical : Error<
@@ -1452,6 +1454,8 @@ def warn_unknown_declare_variant_isa_trait
               "spelling or consider restricting the context selector with the "
               "'arch' selector further">,
       InGroup<SourceUsesOpenMP>;
+def note_ompx_bare_clause : Note<
+  "OpenMP extension clause '%0' only allowed with '#pragma omp %1'">;
 def note_omp_declare_variant_ctx_options
     : Note<"context %select{set|selector|property}0 options are: %1">;
 def warn_omp_declare_variant_expected

clang/include/clang/Sema/Sema.h

@@ -12447,6 +12447,10 @@ class Sema final {
                                          SourceLocation LParenLoc,
                                          SourceLocation EndLoc);
 
+  /// Called on a well-formed 'ompx_bare' clause.
+  OMPClause *ActOnOpenMPXBareClause(SourceLocation StartLoc,
+                                    SourceLocation EndLoc);
+
   /// The kind of conversion being performed.
   enum CheckedConversionKind {
     /// An implicit conversion.

clang/lib/AST/OpenMPClause.cpp

@@ -170,6 +170,7 @@ const OMPClauseWithPreInit *OMPClauseWithPreInit::get(const OMPClause *C) {
   case OMPC_affinity:
   case OMPC_when:
   case OMPC_bind:
+  case OMPC_ompx_bare:
     break;
   default:
     break;
@@ -2546,6 +2547,10 @@ void OMPClausePrinter::VisitOMPXAttributeClause(OMPXAttributeClause *Node) {
   OS << ")";
 }
 
+void OMPClausePrinter::VisitOMPXBareClause(OMPXBareClause *Node) {
+  OS << "ompx_bare";
+}
+
 void OMPTraitInfo::getAsVariantMatchInfo(ASTContext &ASTCtx,
                                          VariantMatchInfo &VMI) const {
   for (const OMPTraitSet &Set : Sets) {

clang/lib/AST/StmtProfile.cpp

@@ -930,6 +930,7 @@ void OMPClauseProfiler::VisitOMPDoacrossClause(const OMPDoacrossClause *C) {
 }
 void OMPClauseProfiler::VisitOMPXAttributeClause(const OMPXAttributeClause *C) {
 }
+void OMPClauseProfiler::VisitOMPXBareClause(const OMPXBareClause *C) {}
 } // namespace
 
 void

clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp

@@ -551,10 +551,9 @@ CGOpenMPRuntimeGPU::getExecutionMode() const {
   return CurrentExecutionMode;
 }
 
-static CGOpenMPRuntimeGPU::DataSharingMode
-getDataSharingMode(CodeGenModule &CGM) {
-  return CGM.getLangOpts().OpenMPCUDAMode ? CGOpenMPRuntimeGPU::CUDA
-                                          : CGOpenMPRuntimeGPU::Generic;
+CGOpenMPRuntimeGPU::DataSharingMode
+CGOpenMPRuntimeGPU::getDataSharingMode() const {
+  return CurrentDataSharingMode;
 }
 
 /// Check for inner (nested) SPMD construct, if any
@@ -752,6 +751,9 @@ void CGOpenMPRuntimeGPU::emitNonSPMDKernel(const OMPExecutableDirective &D,
   EntryFunctionState EST;
   WrapperFunctionsMap.clear();
 
+  [[maybe_unused]] bool IsBareKernel = D.getSingleClause<OMPXBareClause>();
+  assert(!IsBareKernel && "bare kernel should not be at generic mode");
+
   // Emit target region as a standalone region.
   class NVPTXPrePostActionTy : public PrePostActionTy {
     CGOpenMPRuntimeGPU::EntryFunctionState &EST;
@@ -760,15 +762,13 @@ void CGOpenMPRuntimeGPU::emitNonSPMDKernel(const OMPExecutableDirective &D,
     NVPTXPrePostActionTy(CGOpenMPRuntimeGPU::EntryFunctionState &EST)
         : EST(EST) {}
     void Enter(CodeGenFunction &CGF) override {
-      auto &RT =
-          static_cast<CGOpenMPRuntimeGPU &>(CGF.CGM.getOpenMPRuntime());
+      auto &RT = static_cast<CGOpenMPRuntimeGPU &>(CGF.CGM.getOpenMPRuntime());
       RT.emitKernelInit(CGF, EST, /* IsSPMD */ false);
       // Skip target region initialization.
       RT.setLocThreadIdInsertPt(CGF, /*AtCurrentPoint=*/true);
     }
     void Exit(CodeGenFunction &CGF) override {
-      auto &RT =
-          static_cast<CGOpenMPRuntimeGPU &>(CGF.CGM.getOpenMPRuntime());
+      auto &RT = static_cast<CGOpenMPRuntimeGPU &>(CGF.CGM.getOpenMPRuntime());
       RT.clearLocThreadIdInsertPt(CGF);
       RT.emitKernelDeinit(CGF, EST, /* IsSPMD */ false);
     }
@@ -807,25 +807,39 @@ void CGOpenMPRuntimeGPU::emitSPMDKernel(const OMPExecutableDirective &D,
   ExecutionRuntimeModesRAII ModeRAII(CurrentExecutionMode, EM_SPMD);
   EntryFunctionState EST;
 
+  bool IsBareKernel = D.getSingleClause<OMPXBareClause>();
+
   // Emit target region as a standalone region.
   class NVPTXPrePostActionTy : public PrePostActionTy {
     CGOpenMPRuntimeGPU &RT;
     CGOpenMPRuntimeGPU::EntryFunctionState &EST;
+    bool IsBareKernel;
+    DataSharingMode Mode;
 
   public:
     NVPTXPrePostActionTy(CGOpenMPRuntimeGPU &RT,
-                         CGOpenMPRuntimeGPU::EntryFunctionState &EST)
-        : RT(RT), EST(EST) {}
+                         CGOpenMPRuntimeGPU::EntryFunctionState &EST,
+                         bool IsBareKernel)
+        : RT(RT), EST(EST), IsBareKernel(IsBareKernel),
+          Mode(RT.CurrentDataSharingMode) {}
     void Enter(CodeGenFunction &CGF) override {
+      if (IsBareKernel) {
+        RT.CurrentDataSharingMode = DataSharingMode::DS_CUDA;
+        return;
+      }
       RT.emitKernelInit(CGF, EST, /* IsSPMD */ true);
       // Skip target region initialization.
       RT.setLocThreadIdInsertPt(CGF, /*AtCurrentPoint=*/true);
     }
     void Exit(CodeGenFunction &CGF) override {
+      if (IsBareKernel) {
+        RT.CurrentDataSharingMode = Mode;
+        return;
+      }
       RT.clearLocThreadIdInsertPt(CGF);
       RT.emitKernelDeinit(CGF, EST, /* IsSPMD */ true);
     }
-  } Action(*this, EST);
+  } Action(*this, EST, IsBareKernel);
   CodeGen.setAction(Action);
   IsInTTDRegion = true;
   emitTargetOutlinedFunctionHelper(D, ParentName, OutlinedFn, OutlinedFnID,
@@ -843,7 +857,8 @@ void CGOpenMPRuntimeGPU::emitTargetOutlinedFunction(
   assert(!ParentName.empty() && "Invalid target region parent name!");
 
   bool Mode = supportsSPMDExecutionMode(CGM.getContext(), D);
-  if (Mode)
+  bool IsBareKernel = D.getSingleClause<OMPXBareClause>();
+  if (Mode || IsBareKernel)
     emitSPMDKernel(D, ParentName, OutlinedFn, OutlinedFnID, IsOffloadEntry,
                    CodeGen);
   else
@@ -867,6 +882,9 @@ CGOpenMPRuntimeGPU::CGOpenMPRuntimeGPU(CodeGenModule &CGM)
   if (CGM.getLangOpts().NoGPULib || CGM.getLangOpts().OMPHostIRFile.empty())
     return;
 
+  if (CGM.getLangOpts().OpenMPCUDAMode)
+    CurrentDataSharingMode = CGOpenMPRuntimeGPU::DS_CUDA;
+
   OMPBuilder.createGlobalFlag(CGM.getLangOpts().OpenMPTargetDebug,
                               "__omp_rtl_debug_kind");
   OMPBuilder.createGlobalFlag(CGM.getLangOpts().OpenMPTeamSubscription,
@@ -1030,7 +1048,7 @@ llvm::Function *CGOpenMPRuntimeGPU::emitTeamsOutlinedFunction(
 void CGOpenMPRuntimeGPU::emitGenericVarsProlog(CodeGenFunction &CGF,
                                                  SourceLocation Loc,
                                                  bool WithSPMDCheck) {
-  if (getDataSharingMode(CGM) != CGOpenMPRuntimeGPU::Generic &&
+  if (getDataSharingMode() != CGOpenMPRuntimeGPU::DS_Generic &&
       getExecutionMode() != CGOpenMPRuntimeGPU::EM_SPMD)
     return;
 
@@ -1142,7 +1160,7 @@ void CGOpenMPRuntimeGPU::getKmpcFreeShared(
 
 void CGOpenMPRuntimeGPU::emitGenericVarsEpilog(CodeGenFunction &CGF,
                                                  bool WithSPMDCheck) {
-  if (getDataSharingMode(CGM) != CGOpenMPRuntimeGPU::Generic &&
+  if (getDataSharingMode() != CGOpenMPRuntimeGPU::DS_Generic &&
       getExecutionMode() != CGOpenMPRuntimeGPU::EM_SPMD)
     return;
 
@@ -1178,11 +1196,18 @@ void CGOpenMPRuntimeGPU::emitTeamsCall(CodeGenFunction &CGF,
   if (!CGF.HaveInsertPoint())
     return;
 
+  bool IsBareKernel = D.getSingleClause<OMPXBareClause>();
+
   Address ZeroAddr = CGF.CreateDefaultAlignTempAlloca(CGF.Int32Ty,
                                                       /*Name=*/".zero.addr");
   CGF.Builder.CreateStore(CGF.Builder.getInt32(/*C*/ 0), ZeroAddr);
   llvm::SmallVector<llvm::Value *, 16> OutlinedFnArgs;
-  OutlinedFnArgs.push_back(emitThreadIDAddress(CGF, Loc).getPointer());
+  // We don't emit any thread id function call in bare kernel, but because the
+  // outlined function has a pointer argument, we emit a nullptr here.
+  if (IsBareKernel)
+    OutlinedFnArgs.push_back(llvm::ConstantPointerNull::get(CGM.VoidPtrTy));
+  else
+    OutlinedFnArgs.push_back(emitThreadIDAddress(CGF, Loc).getPointer());
   OutlinedFnArgs.push_back(ZeroAddr.getPointer());
   OutlinedFnArgs.append(CapturedVars.begin(), CapturedVars.end());
   emitOutlinedFunctionCall(CGF, Loc, OutlinedFn, OutlinedFnArgs);
@@ -3273,7 +3298,7 @@ llvm::Function *CGOpenMPRuntimeGPU::createParallelDataSharingWrapper(
 
 void CGOpenMPRuntimeGPU::emitFunctionProlog(CodeGenFunction &CGF,
                                               const Decl *D) {
-  if (getDataSharingMode(CGM) != CGOpenMPRuntimeGPU::Generic)
+  if (getDataSharingMode() != CGOpenMPRuntimeGPU::DS_Generic)
     return;
 
   assert(D && "Expected function or captured|block decl.");
@@ -3382,7 +3407,7 @@ Address CGOpenMPRuntimeGPU::getAddressOfLocalVariable(CodeGenFunction &CGF,
         VarTy, Align);
   }
 
-  if (getDataSharingMode(CGM) != CGOpenMPRuntimeGPU::Generic)
+  if (getDataSharingMode() != CGOpenMPRuntimeGPU::DS_Generic)
     return Address::invalid();
 
   VD = VD->getCanonicalDecl();

clang/lib/CodeGen/CGOpenMPRuntimeGPU.h

@@ -32,6 +32,18 @@ class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
     /// Unknown execution mode (orphaned directive).
     EM_Unknown,
   };
+
+  /// Target codegen is specialized based on two data-sharing modes: CUDA, in
+  /// which the local variables are actually global threadlocal, and Generic, in
+  /// which the local variables are placed in global memory if they may escape
+  /// their declaration context.
+  enum DataSharingMode {
+    /// CUDA data sharing mode.
+    DS_CUDA,
+    /// Generic data-sharing mode.
+    DS_Generic,
+  };
+
 private:
   /// Parallel outlined function work for workers to execute.
   llvm::SmallVector<llvm::Function *, 16> Work;
@@ -42,6 +54,8 @@ class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
 
   ExecutionMode getExecutionMode() const;
 
+  DataSharingMode getDataSharingMode() const;
+
   /// Get barrier to synchronize all threads in a block.
   void syncCTAThreads(CodeGenFunction &CGF);
 
@@ -297,17 +311,6 @@ class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
   Address getAddressOfLocalVariable(CodeGenFunction &CGF,
                                     const VarDecl *VD) override;
 
-  /// Target codegen is specialized based on two data-sharing modes: CUDA, in
-  /// which the local variables are actually global threadlocal, and Generic, in
-  /// which the local variables are placed in global memory if they may escape
-  /// their declaration context.
-  enum DataSharingMode {
-    /// CUDA data sharing mode.
-    CUDA,
-    /// Generic data-sharing mode.
-    Generic,
-  };
-
   /// Cleans up references to the objects in finished function.
   ///
   void functionFinished(CodeGenFunction &CGF) override;
@@ -343,6 +346,10 @@ class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
   /// to emit optimized code.
   ExecutionMode CurrentExecutionMode = EM_Unknown;
 
+  /// Track the data sharing mode when codegening directives within a target
+  /// region.
+  DataSharingMode CurrentDataSharingMode = DataSharingMode::DS_Generic;
+
   /// true if currently emitting code for target/teams/distribute region, false
   /// - otherwise.
   bool IsInTTDRegion = false;

clang/lib/Parse/ParseOpenMP.cpp

@@ -3416,6 +3416,17 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
   case OMPC_ompx_attribute:
     Clause = ParseOpenMPOMPXAttributesClause(WrongDirective);
     break;
+  case OMPC_ompx_bare:
+    if (WrongDirective)
+      Diag(Tok, diag::note_ompx_bare_clause)
+          << getOpenMPClauseName(CKind) << "target teams";
+    if (!ErrorFound && !getLangOpts().OpenMPExtensions) {
+      Diag(Tok, diag::err_omp_unexpected_clause_extension_only)
+          << getOpenMPClauseName(CKind) << getOpenMPDirectiveName(DKind);
+      ErrorFound = true;
+    }
+    Clause = ParseOpenMPClause(CKind, WrongDirective);
+    break;
   default:
     break;
   }

clang/lib/Sema/SemaOpenMP.cpp

@@ -17553,6 +17553,9 @@ OMPClause *Sema::ActOnOpenMPClause(OpenMPClauseKind Kind,
   case OMPC_partial:
     Res = ActOnOpenMPPartialClause(nullptr, StartLoc, /*LParenLoc=*/{}, EndLoc);
     break;
+  case OMPC_ompx_bare:
+    Res = ActOnOpenMPXBareClause(StartLoc, EndLoc);
+    break;
   case OMPC_if:
   case OMPC_final:
   case OMPC_num_threads:
@@ -24279,3 +24282,8 @@ OMPClause *Sema::ActOnOpenMPXAttributeClause(ArrayRef<const Attr *> Attrs,
                                              SourceLocation EndLoc) {
   return new (Context) OMPXAttributeClause(Attrs, StartLoc, LParenLoc, EndLoc);
 }
+
+OMPClause *Sema::ActOnOpenMPXBareClause(SourceLocation StartLoc,
+                                        SourceLocation EndLoc) {
+  return new (Context) OMPXBareClause(StartLoc, EndLoc);
+}

clang/lib/Sema/TreeTransform.h

@@ -2391,6 +2391,15 @@ class TreeTransform {
                                                  EndLoc);
   }
 
+  /// Build a new OpenMP 'ompx_bare' clause.
+  ///
+  /// By default, performs semantic analysis to build the new OpenMP clause.
+  /// Subclasses may override this routine to provide different behavior.
+  OMPClause *RebuildOMPXBareClause(SourceLocation StartLoc,
+                                   SourceLocation EndLoc) {
+    return getSema().ActOnOpenMPXBareClause(StartLoc, EndLoc);
+  }
+
   /// Build a new OpenMP 'align' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
@@ -10804,6 +10813,11 @@ TreeTransform<Derived>::TransformOMPXAttributeClause(OMPXAttributeClause *C) {
       NewAttrs, C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
 }
 
+template <typename Derived>
+OMPClause *TreeTransform<Derived>::TransformOMPXBareClause(OMPXBareClause *C) {
+  return getDerived().RebuildOMPXBareClause(C->getBeginLoc(), C->getEndLoc());
+}
+
 //===----------------------------------------------------------------------===//
 // Expression transformation
 //===----------------------------------------------------------------------===//

clang/lib/Serialization/ASTReader.cpp

@@ -10446,6 +10446,9 @@ OMPClause *OMPClauseReader::readClause() {
   case llvm::omp::OMPC_ompx_attribute:
     C = new (Context) OMPXAttributeClause();
     break;
+  case llvm::omp::OMPC_ompx_bare:
+    C = new (Context) OMPXBareClause();
+    break;
 #define OMP_CLAUSE_NO_CLASS(Enum, Str)                                         \
   case llvm::omp::Enum:                                                        \
     break;
@@ -11547,6 +11550,8 @@ void OMPClauseReader::VisitOMPXAttributeClause(OMPXAttributeClause *C) {
   C->setLocEnd(Record.readSourceLocation());
 }
 
+void OMPClauseReader::VisitOMPXBareClause(OMPXBareClause *C) {}
+
 OMPTraitInfo *ASTRecordReader::readOMPTraitInfo() {
   OMPTraitInfo &TI = getContext().getNewOMPTraitInfo();
   TI.Sets.resize(readUInt32());