[OPENMP50]Codegen for iterator construct.

Implemented codegen for the iterator expression in the depend clauses.
Iterator construct is emitted the following way:
iterator(cnt1, cnt2, ...), in : <dep>

<TotalNumDeps> = <cnt1_size> * <cnt2_size> * ...;
kmp_depend_t deps[<TotalNumDeps>];
deps_counter = 0;
for (cnt1) {
  for (cnt2) {
    ...
    deps[deps_counter].base_addr = &<dep>;
    deps[deps_counter].size = sizeof(<dep>);
    deps[deps_counter].flags = in;
    deps_counter += 1;
    ...
  }
}

For depobj construct the codegen is very similar, but the memory is
allocated dynamically and added extra first item reserved for internal use.

Author: alexey-bataev

clang/include/clang/AST/ExprOpenMP.h

@@ -206,6 +206,21 @@ class OMPArrayShapingExpr final
   }
 };
 
+/// Helper expressions and declaration for OMPIteratorExpr class for each
+/// iteration space.
+struct OMPIteratorHelperData {
+  /// Internal normalized counter.
+  VarDecl *CounterVD = nullptr;
+  /// Normalized upper bound. Normalized loop iterates from 0 to Upper with
+  /// step 1.
+  Expr *Upper = nullptr;
+  /// Update expression for the originally specified iteration variable,
+  /// calculated as VD = Begin + CounterVD * Step;
+  Expr *Update = nullptr;
+  /// Updater for the internal counter: ++CounterVD;
+  Expr *CounterUpdate = nullptr;
+};
+
 /// OpenMP 5.0 [2.1.6 Iterators]
 /// Iterators are identifiers that expand to multiple values in the clause on
 /// which they appear.
@@ -233,7 +248,7 @@ class OMPArrayShapingExpr final
 class OMPIteratorExpr final
     : public Expr,
       private llvm::TrailingObjects<OMPIteratorExpr, Decl *, Expr *,
-                                    SourceLocation> {
+                                    SourceLocation, OMPIteratorHelperData> {
 public:
   /// Iterator range representation begin:end[:step].
   struct IteratorRange {
@@ -280,7 +295,8 @@ class OMPIteratorExpr final
 
   OMPIteratorExpr(QualType ExprTy, SourceLocation IteratorKwLoc,
                   SourceLocation L, SourceLocation R,
-                  ArrayRef<OMPIteratorExpr::IteratorDefinition> Data);
+                  ArrayRef<IteratorDefinition> Data,
+                  ArrayRef<OMPIteratorHelperData> Helpers);
 
   /// Construct an empty expression.
   explicit OMPIteratorExpr(EmptyShell Shell, unsigned NumIterators)
@@ -298,6 +314,9 @@ class OMPIteratorExpr final
   void setIteratorRange(unsigned I, Expr *Begin, SourceLocation ColonLoc,
                         Expr *End, SourceLocation SecondColonLoc, Expr *Step);
 
+  /// Sets helpers for the specified iteration space.
+  void setHelper(unsigned I, const OMPIteratorHelperData &D);
+
   unsigned numTrailingObjects(OverloadToken<Decl *>) const {
     return NumIterators;
   }
@@ -306,11 +325,16 @@ class OMPIteratorExpr final
     return NumIterators * static_cast<int>(RangeExprOffset::Total);
   }
 
+  unsigned numTrailingObjects(OverloadToken<SourceLocation>) const {
+    return NumIterators * static_cast<int>(RangeLocOffset::Total);
+  }
+
 public:
   static OMPIteratorExpr *Create(const ASTContext &Context, QualType T,
                                  SourceLocation IteratorKwLoc, SourceLocation L,
                                  SourceLocation R,
-                                 ArrayRef<IteratorDefinition> Data);
+                                 ArrayRef<IteratorDefinition> Data,
+                                 ArrayRef<OMPIteratorHelperData> Helpers);
 
   static OMPIteratorExpr *CreateEmpty(const ASTContext &Context,
                                       unsigned NumIterators);
@@ -350,6 +374,10 @@ class OMPIteratorExpr final
   /// Returns number of iterator definitions.
   unsigned numOfIterators() const { return NumIterators; }
 
+  /// Fetches helper data for the specified iteration space.
+  OMPIteratorHelperData &getHelper(unsigned I);
+  const OMPIteratorHelperData &getHelper(unsigned I) const;
+
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == OMPIteratorExprClass;
   }

clang/lib/AST/Expr.cpp

@@ -4695,9 +4695,22 @@ SourceLocation OMPIteratorExpr::getSecondColonLoc(unsigned I) const {
                         static_cast<int>(RangeLocOffset::SecondColonLoc)];
 }
 
+void OMPIteratorExpr::setHelper(unsigned I, const OMPIteratorHelperData &D) {
+  getTrailingObjects<OMPIteratorHelperData>()[I] = D;
+}
+
+OMPIteratorHelperData &OMPIteratorExpr::getHelper(unsigned I) {
+  return getTrailingObjects<OMPIteratorHelperData>()[I];
+}
+
+const OMPIteratorHelperData &OMPIteratorExpr::getHelper(unsigned I) const {
+  return getTrailingObjects<OMPIteratorHelperData>()[I];
+}
+
 OMPIteratorExpr::OMPIteratorExpr(
     QualType ExprTy, SourceLocation IteratorKwLoc, SourceLocation L,
-    SourceLocation R, ArrayRef<OMPIteratorExpr::IteratorDefinition> Data)
+    SourceLocation R, ArrayRef<OMPIteratorExpr::IteratorDefinition> Data,
+    ArrayRef<OMPIteratorHelperData> Helpers)
     : Expr(OMPIteratorExprClass, ExprTy, VK_LValue, OK_Ordinary),
       IteratorKwLoc(IteratorKwLoc), LPLoc(L), RPLoc(R),
       NumIterators(Data.size()) {
@@ -4707,6 +4720,7 @@ OMPIteratorExpr::OMPIteratorExpr(
     setAssignmentLoc(I, D.AssignmentLoc);
     setIteratorRange(I, D.Range.Begin, D.ColonLoc, D.Range.End,
                      D.SecondColonLoc, D.Range.Step);
+    setHelper(I, Helpers[I]);
   }
   setDependence(computeDependence(this));
 }
@@ -4715,21 +4729,25 @@ OMPIteratorExpr *
 OMPIteratorExpr::Create(const ASTContext &Context, QualType T,
                         SourceLocation IteratorKwLoc, SourceLocation L,
                         SourceLocation R,
-                        ArrayRef<OMPIteratorExpr::IteratorDefinition> Data) {
+                        ArrayRef<OMPIteratorExpr::IteratorDefinition> Data,
+                        ArrayRef<OMPIteratorHelperData> Helpers) {
+  assert(Data.size() == Helpers.size() &&
+         "Data and helpers must have the same size.");
   void *Mem = Context.Allocate(
-      totalSizeToAlloc<Decl *, Expr *, SourceLocation>(
+      totalSizeToAlloc<Decl *, Expr *, SourceLocation, OMPIteratorHelperData>(
           Data.size(), Data.size() * static_cast<int>(RangeExprOffset::Total),
-          Data.size() * static_cast<int>(RangeLocOffset::Total)),
+          Data.size() * static_cast<int>(RangeLocOffset::Total),
+          Helpers.size()),
       alignof(OMPIteratorExpr));
-  return new (Mem) OMPIteratorExpr(T, IteratorKwLoc, L, R, Data);
+  return new (Mem) OMPIteratorExpr(T, IteratorKwLoc, L, R, Data, Helpers);
 }
 
 OMPIteratorExpr *OMPIteratorExpr::CreateEmpty(const ASTContext &Context,
                                               unsigned NumIterators) {
   void *Mem = Context.Allocate(
-      totalSizeToAlloc<Decl *, Expr *, SourceLocation>(
+      totalSizeToAlloc<Decl *, Expr *, SourceLocation, OMPIteratorHelperData>(
           NumIterators, NumIterators * static_cast<int>(RangeExprOffset::Total),
-          NumIterators * static_cast<int>(RangeLocOffset::Total)),
+          NumIterators * static_cast<int>(RangeLocOffset::Total), NumIterators),
       alignof(OMPIteratorExpr));
   return new (Mem) OMPIteratorExpr(EmptyShell(), NumIterators);
 }