[OpenACC] Implement Default clause for Compute Constructs (#88135)

As a followup to my previous commits, this is an implementation of a
single clause, in this case the 'default' clause. This implements all
semantic analysis for it on compute clauses, and continues to leave it
rejected for all others (some as 'doesnt appertain', others as 'not
implemented' as appropriate).

This also implements and tests the TreeTransform as requested in the
previous patch.

Author: erichkeane

clang/include/clang/AST/OpenACCClause.h

@@ -51,6 +51,36 @@ class OpenACCClauseWithParams : public OpenACCClause {
   SourceLocation getLParenLoc() const { return LParenLoc; }
 };
 
+/// A 'default' clause, has the optional 'none' or 'present' argument.
+class OpenACCDefaultClause : public OpenACCClauseWithParams {
+  friend class ASTReaderStmt;
+  friend class ASTWriterStmt;
+
+  OpenACCDefaultClauseKind DefaultClauseKind;
+
+protected:
+  OpenACCDefaultClause(OpenACCDefaultClauseKind K, SourceLocation BeginLoc,
+                       SourceLocation LParenLoc, SourceLocation EndLoc)
+      : OpenACCClauseWithParams(OpenACCClauseKind::Default, BeginLoc, LParenLoc,
+                                EndLoc),
+        DefaultClauseKind(K) {
+    assert((DefaultClauseKind == OpenACCDefaultClauseKind::None ||
+            DefaultClauseKind == OpenACCDefaultClauseKind::Present) &&
+           "Invalid Clause Kind");
+  }
+
+public:
+  OpenACCDefaultClauseKind getDefaultClauseKind() const {
+    return DefaultClauseKind;
+  }
+
+  static OpenACCDefaultClause *Create(const ASTContext &C,
+                                      OpenACCDefaultClauseKind K,
+                                      SourceLocation BeginLoc,
+                                      SourceLocation LParenLoc,
+                                      SourceLocation EndLoc);
+};
+
 template <class Impl> class OpenACCClauseVisitor {
   Impl &getDerived() { return static_cast<Impl &>(*this); }
 
@@ -66,6 +96,8 @@ template <class Impl> class OpenACCClauseVisitor {
 
     switch (C->getClauseKind()) {
     case OpenACCClauseKind::Default:
+      VisitOpenACCDefaultClause(*cast<OpenACCDefaultClause>(C));
+      return;
     case OpenACCClauseKind::Finalize:
     case OpenACCClauseKind::IfPresent:
     case OpenACCClauseKind::Seq:
@@ -112,6 +144,10 @@ template <class Impl> class OpenACCClauseVisitor {
     }
     llvm_unreachable("Invalid Clause kind");
   }
+
+  void VisitOpenACCDefaultClause(const OpenACCDefaultClause &Clause) {
+    return getDerived().VisitOpenACCDefaultClause(Clause);
+  }
 };
 
 class OpenACCClausePrinter final
@@ -128,6 +164,8 @@ class OpenACCClausePrinter final
     }
   }
   OpenACCClausePrinter(raw_ostream &OS) : OS(OS) {}
+
+  void VisitOpenACCDefaultClause(const OpenACCDefaultClause &Clause);
 };
 
 } // namespace clang

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -12265,6 +12265,10 @@ def err_acc_construct_appertainment
             "be used in a statement context">;
 def err_acc_clause_appertainment
     : Error<"OpenACC '%1' clause is not valid on '%0' directive">;
+def err_acc_duplicate_clause_disallowed
+    : Error<"OpenACC '%1' clause cannot appear more than once on a '%0' "
+            "directive">;
+def note_acc_previous_clause_here : Note<"previous clause is here">;
 def err_acc_branch_in_out_compute_construct
     : Error<"invalid %select{branch|return|throw}0 %select{out of|into}1 "
             "OpenACC Compute Construct">;

clang/include/clang/Basic/OpenACCKinds.h

@@ -419,6 +419,29 @@ enum class OpenACCDefaultClauseKind {
   Invalid,
 };
 
+template <typename StreamTy>
+inline StreamTy &printOpenACCDefaultClauseKind(StreamTy &Out,
+                                               OpenACCDefaultClauseKind K) {
+  switch (K) {
+  case OpenACCDefaultClauseKind::None:
+    return Out << "none";
+  case OpenACCDefaultClauseKind::Present:
+    return Out << "present";
+  case OpenACCDefaultClauseKind::Invalid:
+    return Out << "<invalid>";
+  }
+}
+
+inline const StreamingDiagnostic &operator<<(const StreamingDiagnostic &Out,
+                                             OpenACCDefaultClauseKind K) {
+  return printOpenACCDefaultClauseKind(Out, K);
+}
+
+inline llvm::raw_ostream &operator<<(llvm::raw_ostream &Out,
+                                     OpenACCDefaultClauseKind K) {
+  return printOpenACCDefaultClauseKind(Out, K);
+}
+
 enum class OpenACCReductionOperator {
   /// '+'.
   Addition,

clang/include/clang/Sema/SemaOpenACC.h

@@ -19,6 +19,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Sema/Ownership.h"
 #include "clang/Sema/SemaBase.h"
+#include <variant>
 
 namespace clang {
 class OpenACCClause;
@@ -35,7 +36,11 @@ class SemaOpenACC : public SemaBase {
     SourceRange ClauseRange;
     SourceLocation LParenLoc;
 
-    // TODO OpenACC: Add variant here to store details of individual clauses.
+    struct DefaultDetails {
+      OpenACCDefaultClauseKind DefaultClauseKind;
+    };
+
+    std::variant<DefaultDetails> Details;
 
   public:
     OpenACCParsedClause(OpenACCDirectiveKind DirKind,
@@ -52,8 +57,20 @@ class SemaOpenACC : public SemaBase {
 
     SourceLocation getEndLoc() const { return ClauseRange.getEnd(); }
 
+    OpenACCDefaultClauseKind getDefaultClauseKind() const {
+      assert(ClauseKind == OpenACCClauseKind::Default &&
+             "Parsed clause is not a default clause");
+      return std::get<DefaultDetails>(Details).DefaultClauseKind;
+    }
+
     void setLParenLoc(SourceLocation EndLoc) { LParenLoc = EndLoc; }
     void setEndLoc(SourceLocation EndLoc) { ClauseRange.setEnd(EndLoc); }
+
+    void setDefaultDetails(OpenACCDefaultClauseKind DefKind) {
+      assert(ClauseKind == OpenACCClauseKind::Default &&
+             "Parsed clause is not a default clause");
+      Details = DefaultDetails{DefKind};
+    }
   };
 
   SemaOpenACC(Sema &S);

clang/lib/AST/OpenACCClause.cpp

@@ -15,3 +15,22 @@
 #include "clang/AST/ASTContext.h"
 
 using namespace clang;
+
+OpenACCDefaultClause *OpenACCDefaultClause::Create(const ASTContext &C,
+                                                   OpenACCDefaultClauseKind K,
+                                                   SourceLocation BeginLoc,
+                                                   SourceLocation LParenLoc,
+                                                   SourceLocation EndLoc) {
+  void *Mem =
+      C.Allocate(sizeof(OpenACCDefaultClause), alignof(OpenACCDefaultClause));
+
+  return new (Mem) OpenACCDefaultClause(K, BeginLoc, LParenLoc, EndLoc);
+}
+
+//===----------------------------------------------------------------------===//
+//  OpenACC clauses printing methods
+//===----------------------------------------------------------------------===//
+void OpenACCClausePrinter::VisitOpenACCDefaultClause(
+    const OpenACCDefaultClause &C) {
+  OS << "default(" << C.getDefaultClauseKind() << ")";
+}

clang/lib/AST/StmtProfile.cpp

@@ -2456,7 +2456,12 @@ class OpenACCClauseProfiler
       Visit(Clause);
     }
   }
+  void VisitOpenACCDefaultClause(const OpenACCDefaultClause &Clause);
 };
+
+/// Nothing to do here, there are no sub-statements.
+void OpenACCClauseProfiler::VisitOpenACCDefaultClause(
+    const OpenACCDefaultClause &Clause) {}
 } // namespace
 
 void StmtProfiler::VisitOpenACCComputeConstruct(

clang/lib/AST/TextNodeDumper.cpp

@@ -390,6 +390,17 @@ void TextNodeDumper::Visit(const OpenACCClause *C) {
   {
     ColorScope Color(OS, ShowColors, AttrColor);
     OS << C->getClauseKind();
+
+    // Handle clauses with parens for types that have no children, likely
+    // because there is no sub expression.
+    switch (C->getClauseKind()) {
+    case OpenACCClauseKind::Default:
+      OS << '(' << cast<OpenACCDefaultClause>(C)->getDefaultClauseKind() << ')';
+      break;
+    default:
+      // Nothing to do here.
+      break;
+    }
   }
   dumpPointer(C);
   dumpSourceRange(SourceRange(C->getBeginLoc(), C->getEndLoc()));

clang/lib/Parse/ParseOpenACC.cpp

@@ -831,9 +831,13 @@ Parser::OpenACCClauseParseResult Parser::ParseOpenACCClauseParams(
 
       ConsumeToken();
 
-      if (getOpenACCDefaultClauseKind(DefKindTok) ==
-          OpenACCDefaultClauseKind::Invalid)
+      OpenACCDefaultClauseKind DefKind =
+          getOpenACCDefaultClauseKind(DefKindTok);
+
+      if (DefKind == OpenACCDefaultClauseKind::Invalid)
         Diag(DefKindTok, diag::err_acc_invalid_default_clause_kind);
+      else
+        ParsedClause.setDefaultDetails(DefKind);
 
       break;
     }

clang/lib/Sema/SemaOpenACC.cpp

@@ -39,11 +39,27 @@ bool diagnoseConstructAppertainment(SemaOpenACC &S, OpenACCDirectiveKind K,
 
 bool doesClauseApplyToDirective(OpenACCDirectiveKind DirectiveKind,
                                 OpenACCClauseKind ClauseKind) {
-  // FIXME: For each clause as we implement them, we can add the
-  // 'legalization' list here.
-
-  // Do nothing so we can go to the 'unimplemented' diagnostic instead.
-  return true;
+  switch (ClauseKind) {
+    // FIXME: For each clause as we implement them, we can add the
+    // 'legalization' list here.
+  case OpenACCClauseKind::Default:
+    switch (DirectiveKind) {
+    case OpenACCDirectiveKind::Parallel:
+    case OpenACCDirectiveKind::Serial:
+    case OpenACCDirectiveKind::Kernels:
+    case OpenACCDirectiveKind::ParallelLoop:
+    case OpenACCDirectiveKind::SerialLoop:
+    case OpenACCDirectiveKind::KernelsLoop:
+    case OpenACCDirectiveKind::Data:
+      return true;
+    default:
+      return false;
+    }
+  default:
+    // Do nothing so we can go to the 'unimplemented' diagnostic instead.
+    return true;
+  }
+  llvm_unreachable("Invalid clause kind");
 }
 } // namespace
 
@@ -63,8 +79,43 @@ SemaOpenACC::ActOnClause(ArrayRef<const OpenACCClause *> ExistingClauses,
     return nullptr;
   }
 
-  // TODO OpenACC: Switch over the clauses we implement here and 'create'
-  // them.
+  switch (Clause.getClauseKind()) {
+  case OpenACCClauseKind::Default: {
+    // Restrictions only properly implemented on 'compute' constructs, and
+    // 'compute' constructs are the only construct that can do anything with
+    // this yet, so skip/treat as unimplemented in this case.
+    if (Clause.getDirectiveKind() != OpenACCDirectiveKind::Parallel &&
+        Clause.getDirectiveKind() != OpenACCDirectiveKind::Serial &&
+        Clause.getDirectiveKind() != OpenACCDirectiveKind::Kernels)
+      break;
+
+    // Don't add an invalid clause to the AST.
+    if (Clause.getDefaultClauseKind() == OpenACCDefaultClauseKind::Invalid)
+      return nullptr;
+
+    // OpenACC 3.3, Section 2.5.4:
+    // At most one 'default' clause may appear, and it must have a value of
+    // either 'none' or 'present'.
+    // Second half of the sentence is diagnosed during parsing.
+    auto Itr = llvm::find_if(ExistingClauses, [](const OpenACCClause *C) {
+      return C->getClauseKind() == OpenACCClauseKind::Default;
+    });
+
+    if (Itr != ExistingClauses.end()) {
+      SemaRef.Diag(Clause.getBeginLoc(),
+                   diag::err_acc_duplicate_clause_disallowed)
+          << Clause.getDirectiveKind() << Clause.getClauseKind();
+      SemaRef.Diag((*Itr)->getBeginLoc(), diag::note_acc_previous_clause_here);
+      return nullptr;
+    }
+
+    return OpenACCDefaultClause::Create(
+        getASTContext(), Clause.getDefaultClauseKind(), Clause.getBeginLoc(),
+        Clause.getLParenLoc(), Clause.getEndLoc());
+  }
+  default:
+    break;
+  }
 
   Diag(Clause.getBeginLoc(), diag::warn_acc_clause_unimplemented)
       << Clause.getClauseKind();

clang/lib/Sema/TreeTransform.h

@@ -4035,6 +4035,11 @@ class TreeTransform {
   llvm::SmallVector<OpenACCClause *>
   TransformOpenACCClauseList(OpenACCDirectiveKind DirKind,
                              ArrayRef<const OpenACCClause *> OldClauses);
+
+  OpenACCClause *
+  TransformOpenACCClause(ArrayRef<const OpenACCClause *> ExistingClauses,
+                         OpenACCDirectiveKind DirKind,
+                         const OpenACCClause *OldClause);
 };
 
 template <typename Derived>
@@ -11075,13 +11080,44 @@ OMPClause *TreeTransform<Derived>::TransformOMPXBareClause(OMPXBareClause *C) {
 //===----------------------------------------------------------------------===//
 // OpenACC transformation
 //===----------------------------------------------------------------------===//
+template <typename Derived>
+OpenACCClause *TreeTransform<Derived>::TransformOpenACCClause(
+    ArrayRef<const OpenACCClause *> ExistingClauses,
+    OpenACCDirectiveKind DirKind, const OpenACCClause *OldClause) {
+
+  SemaOpenACC::OpenACCParsedClause ParsedClause(
+      DirKind, OldClause->getClauseKind(), OldClause->getBeginLoc());
+  ParsedClause.setEndLoc(OldClause->getEndLoc());
+
+  if (const auto *WithParms = dyn_cast<OpenACCClauseWithParams>(OldClause))
+    ParsedClause.setLParenLoc(WithParms->getLParenLoc());
+
+  switch (OldClause->getClauseKind()) {
+  case OpenACCClauseKind::Default:
+    // There is nothing to do here as nothing dependent can appear in this
+    // clause. So just set the values so Sema can set the right value.
+    ParsedClause.setDefaultDetails(
+        cast<OpenACCDefaultClause>(OldClause)->getDefaultClauseKind());
+    break;
+  default:
+    assert(false && "Unhandled OpenACC clause in TreeTransform");
+    return nullptr;
+  }
+
+  return getSema().OpenACC().ActOnClause(ExistingClauses, ParsedClause);
+}
+
 template <typename Derived>
 llvm::SmallVector<OpenACCClause *>
 TreeTransform<Derived>::TransformOpenACCClauseList(
     OpenACCDirectiveKind DirKind, ArrayRef<const OpenACCClause *> OldClauses) {
-  // TODO OpenACC: Ensure we loop through the list and transform the individual
-  // clauses.
-  return {};
+  llvm::SmallVector<OpenACCClause *> TransformedClauses;
+  for (const auto *Clause : OldClauses) {
+    if (OpenACCClause *TransformedClause = getDerived().TransformOpenACCClause(
+            TransformedClauses, DirKind, Clause))
+      TransformedClauses.push_back(TransformedClause);
+  }
+  return TransformedClauses;
 }
 
 template <typename Derived>