[OPENMP 4.0] Initial support for 'omp declare reduction' construct.

Add parsing, sema analysis and serialization/deserialization for 'declare reduction' construct.
User-defined reductions are defined as

#pragma omp declare reduction( reduction-identifier : typename-list : combiner ) [initializer ( initializer-expr )]
These custom reductions may be used in 'reduction' clauses of OpenMP constructs. The combiner specifies how partial results can be combined into a single value. The
combiner can use the special variable identifiers omp_in and omp_out that are of the type of the variables being reduced with this reduction-identifier. Each of them will
denote one of the values to be combined before executing the combiner. It is assumed that the special omp_out identifier will refer to the storage that holds the resulting
combined value after executing the combiner.
As the initializer-expr value of a user-defined reduction is not known a priori the initializer-clause can be used to specify one. Then the contents of the initializer-clause
will be used as the initializer for private copies of reduction list items where the omp_priv identifier will refer to the storage to be initialized. The special identifier
omp_orig can also appear in the initializer-clause and it will refer to the storage of the original variable to be reduced.
Differential Revision: http://reviews.llvm.org/D11182

llvm-svn: 262582

6 files changed, 332 insertions, 2 deletions

diff --git a/clang/lib/Sema/ScopeInfo.cpp b/clang/lib/Sema/ScopeInfo.cpp
index cbd7ef7abb4..ef9eed65ebc 100644
--- a/clang/lib/Sema/ScopeInfo.cpp
+++ b/clang/lib/Sema/ScopeInfo.cpp
@@ -28,6 +28,7 @@ void FunctionScopeInfo::Clear() {
   HasBranchIntoScope = false;
   HasIndirectGoto = false;
   HasDroppedStmt = false;
+  HasOMPDeclareReductionCombiner = false;
   ObjCShouldCallSuper = false;
   ObjCIsDesignatedInit = false;
   ObjCWarnForNoDesignatedInitChain = false;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index f7fe506f4ae..f20b4d06287 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5640,7 +5640,7 @@ static bool isIncompleteDeclExternC(Sema &S, const T *D) {
 
 static bool shouldConsiderLinkage(const VarDecl *VD) {
   const DeclContext *DC = VD->getDeclContext()->getRedeclContext();
-  if (DC->isFunctionOrMethod())
+  if (DC->isFunctionOrMethod() || isa<OMPDeclareReductionDecl>(DC))
     return VD->hasExternalStorage();
   if (DC->isFileContext())
     return true;
@@ -5651,7 +5651,8 @@ static bool shouldConsiderLinkage(const VarDecl *VD) {
 
 static bool shouldConsiderLinkage(const FunctionDecl *FD) {
   const DeclContext *DC = FD->getDeclContext()->getRedeclContext();
-  if (DC->isFileContext() || DC->isFunctionOrMethod())
+  if (DC->isFileContext() || DC->isFunctionOrMethod() ||
+      isa<OMPDeclareReductionDecl>(DC))
     return true;
   if (DC->isRecord())
     return false;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 0ca5555e1da..b644ff215cd 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -376,6 +376,19 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
         DeduceReturnType(FD, Loc))
       return true;
   }
+
+  // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
+  // Only the variables omp_in and omp_out are allowed in the combiner.
+  // Only the variables omp_priv and omp_orig are allowed in the
+  // initializer-clause.
+  auto *DRD = dyn_cast<OMPDeclareReductionDecl>(CurContext);
+  if (LangOpts.OpenMP && DRD && !CurContext->containsDecl(D) &&
+      isa<VarDecl>(D)) {
+    Diag(Loc, diag::err_omp_wrong_var_in_declare_reduction)
+        << getCurFunction()->HasOMPDeclareReductionCombiner;
+    Diag(D->getLocation(), diag::note_entity_declared_at) << D;
+    return true;
+  }
   DiagnoseAvailabilityOfDecl(*this, D, Loc, UnknownObjCClass,
                              ObjCPropertyAccess);
 
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 4baf6053359..00379336251 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -280,6 +280,10 @@ static inline unsigned getIDNS(Sema::LookupNameKind NameKind,
     IDNS = Decl::IDNS_ObjCProtocol;
     break;
 
+  case Sema::LookupOMPReductionName:
+    IDNS = Decl::IDNS_OMPReduction;
+    break;
+
   case Sema::LookupAnyName:
     IDNS = Decl::IDNS_Ordinary | Decl::IDNS_Tag | Decl::IDNS_Member
       | Decl::IDNS_Using | Decl::IDNS_Namespace | Decl::IDNS_ObjCProtocol
@@ -2015,6 +2019,10 @@ bool Sema::LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
       BaseCallback = &LookupAnyMember;
       break;
 
+    case LookupOMPReductionName:
+      BaseCallback = &CXXRecordDecl::FindOMPReductionMember;
+      break;
+
     case LookupUsingDeclName:
       // This lookup is for redeclarations only.
 
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 50148b5187c..ffac56b1ddd 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -21,6 +21,7 @@
 #include "clang/AST/StmtCXX.h"
 #include "clang/AST/StmtOpenMP.h"
 #include "clang/AST/StmtVisitor.h"
+#include "clang/AST/TypeOrdering.h"
 #include "clang/Basic/OpenMPKinds.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Lex/Preprocessor.h"
@@ -1698,6 +1699,7 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
   case OMPD_flush:
   case OMPD_target_enter_data:
   case OMPD_target_exit_data:
+  case OMPD_declare_reduction:
     llvm_unreachable("OpenMP Directive is not allowed");
   case OMPD_unknown:
     llvm_unreachable("Unknown OpenMP directive");
@@ -3139,6 +3141,7 @@ StmtResult Sema::ActOnOpenMPExecutableDirective(
                                          EndLoc, VarsWithInheritedDSA);
     break;
   case OMPD_threadprivate:
+  case OMPD_declare_reduction:
     llvm_unreachable("OpenMP Directive is not allowed");
   case OMPD_unknown:
     llvm_unreachable("Unknown OpenMP directive");
@@ -9584,6 +9587,235 @@ Sema::ActOnOpenMPMapClause(OpenMPMapClauseKind MapTypeModifier,
                               MapLoc);
 }
 
+QualType Sema::ActOnOpenMPDeclareReductionType(SourceLocation TyLoc,
+                                               TypeResult ParsedType) {
+  assert(ParsedType.isUsable());
+
+  QualType ReductionType = GetTypeFromParser(ParsedType.get());
+  if (ReductionType.isNull())
+    return QualType();
+
+  // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions, C\C++
+  // A type name in a declare reduction directive cannot be a function type, an
+  // array type, a reference type, or a type qualified with const, volatile or
+  // restrict.
+  if (ReductionType.hasQualifiers()) {
+    Diag(TyLoc, diag::err_omp_reduction_wrong_type) << 0;
+    return QualType();
+  }
+
+  if (ReductionType->isFunctionType()) {
+    Diag(TyLoc, diag::err_omp_reduction_wrong_type) << 1;
+    return QualType();
+  }
+  if (ReductionType->isReferenceType()) {
+    Diag(TyLoc, diag::err_omp_reduction_wrong_type) << 2;
+    return QualType();
+  }
+  if (ReductionType->isArrayType()) {
+    Diag(TyLoc, diag::err_omp_reduction_wrong_type) << 3;
+    return QualType();
+  }
+  return ReductionType;
+}
+
+Sema::DeclGroupPtrTy Sema::ActOnOpenMPDeclareReductionDirectiveStart(
+    Scope *S, DeclContext *DC, DeclarationName Name,
+    ArrayRef<std::pair<QualType, SourceLocation>> ReductionTypes,
+    AccessSpecifier AS, Decl *PrevDeclInScope) {
+  SmallVector<Decl *, 8> Decls;
+  Decls.reserve(ReductionTypes.size());
+
+  LookupResult Lookup(*this, Name, SourceLocation(), LookupOMPReductionName,
+                      ForRedeclaration);
+  // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
+  // A reduction-identifier may not be re-declared in the current scope for the
+  // same type or for a type that is compatible according to the base language
+  // rules.
+  llvm::DenseMap<QualType, SourceLocation> PreviousRedeclTypes;
+  OMPDeclareReductionDecl *PrevDRD = nullptr;
+  bool InCompoundScope = true;
+  if (S != nullptr) {
+    // Find previous declaration with the same name not referenced in other
+    // declarations.
+    FunctionScopeInfo *ParentFn = getEnclosingFunction();
+    InCompoundScope =
+        (ParentFn != nullptr) && !ParentFn->CompoundScopes.empty();
+    LookupName(Lookup, S);
+    FilterLookupForScope(Lookup, DC, S, /*ConsiderLinkage=*/false,
+                         /*AllowInlineNamespace=*/false);
+    llvm::DenseMap<OMPDeclareReductionDecl *, bool> UsedAsPrevious;
+    auto Filter = Lookup.makeFilter();
+    while (Filter.hasNext()) {
+      auto *PrevDecl = cast<OMPDeclareReductionDecl>(Filter.next());
+      if (InCompoundScope) {
+        auto I = UsedAsPrevious.find(PrevDecl);
+        if (I == UsedAsPrevious.end())
+          UsedAsPrevious[PrevDecl] = false;
+        if (auto *D = PrevDecl->getPrevDeclInScope())
+          UsedAsPrevious[D] = true;
+      }
+      PreviousRedeclTypes[PrevDecl->getType().getCanonicalType()] =
+          PrevDecl->getLocation();
+    }
+    Filter.done();
+    if (InCompoundScope) {
+      for (auto &PrevData : UsedAsPrevious) {
+        if (!PrevData.second) {
+          PrevDRD = PrevData.first;
+          break;
+        }
+      }
+    }
+  } else if (PrevDeclInScope != nullptr) {
+    auto *PrevDRDInScope = PrevDRD =
+        cast<OMPDeclareReductionDecl>(PrevDeclInScope);
+    do {
+      PreviousRedeclTypes[PrevDRDInScope->getType().getCanonicalType()] =
+          PrevDRDInScope->getLocation();
+      PrevDRDInScope = PrevDRDInScope->getPrevDeclInScope();
+    } while (PrevDRDInScope != nullptr);
+  }
+  for (auto &TyData : ReductionTypes) {
+    auto I = PreviousRedeclTypes.find(TyData.first.getCanonicalType());
+    bool Invalid = false;
+    if (I != PreviousRedeclTypes.end()) {
+      Diag(TyData.second, diag::err_omp_declare_reduction_redefinition)
+          << TyData.first;
+      Diag(I->second, diag::note_previous_definition);
+      Invalid = true;
+    }
+    PreviousRedeclTypes[TyData.first.getCanonicalType()] = TyData.second;
+    auto *DRD = OMPDeclareReductionDecl::Create(Context, DC, TyData.second,
+                                                Name, TyData.first, PrevDRD);
+    DC->addDecl(DRD);
+    DRD->setAccess(AS);
+    Decls.push_back(DRD);
+    if (Invalid)
+      DRD->setInvalidDecl();
+    else
+      PrevDRD = DRD;
+  }
+
+  return DeclGroupPtrTy::make(
+      DeclGroupRef::Create(Context, Decls.begin(), Decls.size()));
+}
+
+void Sema::ActOnOpenMPDeclareReductionCombinerStart(Scope *S, Decl *D) {
+  auto *DRD = cast<OMPDeclareReductionDecl>(D);
+
+  // Enter new function scope.
+  PushFunctionScope();
+  getCurFunction()->setHasBranchProtectedScope();
+  getCurFunction()->setHasOMPDeclareReductionCombiner();
+
+  if (S != nullptr)
+    PushDeclContext(S, DRD);
+  else
+    CurContext = DRD;
+
+  PushExpressionEvaluationContext(PotentiallyEvaluated);
+
+  QualType ReductionType = DRD->getType();
+  // Create 'T omp_in;' implicit param.
+  auto *OmpInParm =
+      ImplicitParamDecl::Create(Context, DRD, D->getLocation(),
+                                &Context.Idents.get("omp_in"), ReductionType);
+  // Create 'T* omp_parm;T omp_out;'. All references to 'omp_out' will
+  // be replaced by '*omp_parm' during codegen. This required because 'omp_out'
+  // uses semantics of argument handles by value, but it should be passed by
+  // reference. C lang does not support references, so pass all parameters as
+  // pointers.
+  // Create 'T omp_out;' variable.
+  auto *OmpOutParm =
+      buildVarDecl(*this, D->getLocation(), ReductionType, "omp_out");
+  if (S != nullptr) {
+    PushOnScopeChains(OmpInParm, S);
+    PushOnScopeChains(OmpOutParm, S);
+  } else {
+    DRD->addDecl(OmpInParm);
+    DRD->addDecl(OmpOutParm);
+  }
+}
+
+void Sema::ActOnOpenMPDeclareReductionCombinerEnd(Decl *D, Expr *Combiner) {
+  auto *DRD = cast<OMPDeclareReductionDecl>(D);
+  DiscardCleanupsInEvaluationContext();
+  PopExpressionEvaluationContext();
+
+  PopDeclContext();
+  PopFunctionScopeInfo();
+
+  if (Combiner != nullptr)
+    DRD->setCombiner(Combiner);
+  else
+    DRD->setInvalidDecl();
+}
+
+void Sema::ActOnOpenMPDeclareReductionInitializerStart(Scope *S, Decl *D) {
+  auto *DRD = cast<OMPDeclareReductionDecl>(D);
+
+  // Enter new function scope.
+  PushFunctionScope();
+  getCurFunction()->setHasBranchProtectedScope();
+
+  if (S != nullptr)
+    PushDeclContext(S, DRD);
+  else
+    CurContext = DRD;
+
+  PushExpressionEvaluationContext(PotentiallyEvaluated);
+
+  QualType ReductionType = DRD->getType();
+  // Create 'T omp_orig;' implicit param.
+  auto *OmpOrigParm =
+      ImplicitParamDecl::Create(Context, DRD, D->getLocation(),
+                                &Context.Idents.get("omp_orig"), ReductionType);
+  // Create 'T* omp_parm;T omp_priv;'. All references to 'omp_priv' will
+  // be replaced by '*omp_parm' during codegen. This required because 'omp_priv'
+  // uses semantics of argument handles by value, but it should be passed by
+  // reference. C lang does not support references, so pass all parameters as
+  // pointers.
+  // Create 'T omp_priv;' variable.
+  auto *OmpPrivParm =
+      buildVarDecl(*this, D->getLocation(), ReductionType, "omp_priv");
+  if (S != nullptr) {
+    PushOnScopeChains(OmpPrivParm, S);
+    PushOnScopeChains(OmpOrigParm, S);
+  } else {
+    DRD->addDecl(OmpPrivParm);
+    DRD->addDecl(OmpOrigParm);
+  }
+}
+
+void Sema::ActOnOpenMPDeclareReductionInitializerEnd(Decl *D,
+                                                     Expr *Initializer) {
+  auto *DRD = cast<OMPDeclareReductionDecl>(D);
+  DiscardCleanupsInEvaluationContext();
+  PopExpressionEvaluationContext();
+
+  PopDeclContext();
+  PopFunctionScopeInfo();
+
+  if (Initializer != nullptr)
+    DRD->setInitializer(Initializer);
+  else
+    DRD->setInvalidDecl();
+}
+
+Sema::DeclGroupPtrTy Sema::ActOnOpenMPDeclareReductionDirectiveEnd(
+    Scope *S, DeclGroupPtrTy DeclReductions, bool IsValid) {
+  for (auto *D : DeclReductions.get()) {
+    if (IsValid) {
+      auto *DRD = cast<OMPDeclareReductionDecl>(D);
+      if (S != nullptr)
+        PushOnScopeChains(DRD, S, /*AddToContext=*/false);
+    } else
+      D->setInvalidDecl();
+  }
+  return DeclReductions;
+}
+
 OMPClause *Sema::ActOnOpenMPNumTeamsClause(Expr *NumTeams, 
                                            SourceLocation StartLoc,
                                            SourceLocation LParenLoc,
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index af93cde68c1..c021b34a4e5 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2503,6 +2503,81 @@ Decl *TemplateDeclInstantiator::VisitOMPThreadPrivateDecl(
   return TD;
 }
 
+Decl *TemplateDeclInstantiator::VisitOMPDeclareReductionDecl(
+    OMPDeclareReductionDecl *D) {
+  // Instantiate type and check if it is allowed.
+  QualType SubstReductionType = SemaRef.ActOnOpenMPDeclareReductionType(
+      D->getLocation(),
+      ParsedType::make(SemaRef.SubstType(D->getType(), TemplateArgs,
+                                         D->getLocation(), DeclarationName())));
+  if (SubstReductionType.isNull())
+    return nullptr;
+  bool IsCorrect = !SubstReductionType.isNull();
+  // Create instantiated copy.
+  std::pair<QualType, SourceLocation> ReductionTypes[] = {
+      std::make_pair(SubstReductionType, D->getLocation())};
+  auto *PrevDeclInScope = D->getPrevDeclInScope();
+  if (PrevDeclInScope && !PrevDeclInScope->isInvalidDecl()) {
+    PrevDeclInScope = cast<OMPDeclareReductionDecl>(
+        SemaRef.CurrentInstantiationScope->findInstantiationOf(PrevDeclInScope)
+            ->get<Decl *>());
+  }
+  auto DRD = SemaRef.ActOnOpenMPDeclareReductionDirectiveStart(
+      /*S=*/nullptr, Owner, D->getDeclName(), ReductionTypes, D->getAccess(),
+      PrevDeclInScope);
+  auto *NewDRD = cast<OMPDeclareReductionDecl>(DRD.get().getSingleDecl());
+  if (isDeclWithinFunction(NewDRD))
+    SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewDRD);
+  Expr *SubstCombiner = nullptr;
+  Expr *SubstInitializer = nullptr;
+  // Combiners instantiation sequence.
+  if (D->getCombiner()) {
+    SemaRef.ActOnOpenMPDeclareReductionCombinerStart(
+        /*S=*/nullptr, NewDRD);
+    const char *Names[] = {"omp_in", "omp_out"};
+    for (auto &Name : Names) {
+      DeclarationName DN(&SemaRef.Context.Idents.get(Name));
+      auto OldLookup = D->lookup(DN);
+      auto Lookup = NewDRD->lookup(DN);
+      if (!OldLookup.empty() && !Lookup.empty()) {
+        assert(Lookup.size() == 1 && OldLookup.size() == 1);
+        SemaRef.CurrentInstantiationScope->InstantiatedLocal(OldLookup.front(),
+                                                             Lookup.front());
+      }
+    }
+    SubstCombiner = SemaRef.SubstExpr(D->getCombiner(), TemplateArgs).get();
+    SemaRef.ActOnOpenMPDeclareReductionCombinerEnd(NewDRD, SubstCombiner);
+    // Initializers instantiation sequence.
+    if (D->getInitializer()) {
+      SemaRef.ActOnOpenMPDeclareReductionInitializerStart(
+          /*S=*/nullptr, NewDRD);
+      const char *Names[] = {"omp_orig", "omp_priv"};
+      for (auto &Name : Names) {
+        DeclarationName DN(&SemaRef.Context.Idents.get(Name));
+        auto OldLookup = D->lookup(DN);
+        auto Lookup = NewDRD->lookup(DN);
+        if (!OldLookup.empty() && !Lookup.empty()) {
+          assert(Lookup.size() == 1 && OldLookup.size() == 1);
+          SemaRef.CurrentInstantiationScope->InstantiatedLocal(
+              OldLookup.front(), Lookup.front());
+        }
+      }
+      SubstInitializer =
+          SemaRef.SubstExpr(D->getInitializer(), TemplateArgs).get();
+      SemaRef.ActOnOpenMPDeclareReductionInitializerEnd(NewDRD,
+                                                        SubstInitializer);
+    }
+    IsCorrect = IsCorrect && SubstCombiner &&
+                (!D->getInitializer() || SubstInitializer);
+  } else
+    IsCorrect = false;
+
+  (void)SemaRef.ActOnOpenMPDeclareReductionDirectiveEnd(/*S=*/nullptr, DRD,
+                                                        IsCorrect);
+
+  return NewDRD;
+}
+
 Decl *TemplateDeclInstantiator::VisitOMPCapturedExprDecl(
     OMPCapturedExprDecl * /*D*/) {
   llvm_unreachable("Should not be met in templates");