4 files changed, 38 insertions, 6 deletions

diff --git a/clang/lib/AST/OpenMPClause.cpp b/clang/lib/AST/OpenMPClause.cpp
index 9d8a7ebc302..7cba4d7039a 100644
--- a/clang/lib/AST/OpenMPClause.cpp
+++ b/clang/lib/AST/OpenMPClause.cpp
@@ -429,15 +429,23 @@ void OMPLinearClause::setFinals(ArrayRef<Expr *> FL) {
   std::copy(FL.begin(), FL.end(), getUpdates().end());
 }
 
+void OMPLinearClause::setUsedExprs(ArrayRef<Expr *> UE) {
+  assert(
+      UE.size() == varlist_size() + 1 &&
+      "Number of used expressions is not the same as the preallocated buffer");
+  std::copy(UE.begin(), UE.end(), getFinals().end() + 2);
+}
+
 OMPLinearClause *OMPLinearClause::Create(
     const ASTContext &C, SourceLocation StartLoc, SourceLocation LParenLoc,
     OpenMPLinearClauseKind Modifier, SourceLocation ModifierLoc,
     SourceLocation ColonLoc, SourceLocation EndLoc, ArrayRef<Expr *> VL,
     ArrayRef<Expr *> PL, ArrayRef<Expr *> IL, Expr *Step, Expr *CalcStep,
     Stmt *PreInit, Expr *PostUpdate) {
-  // Allocate space for 4 lists (Vars, Inits, Updates, Finals) and 2 expressions
-  // (Step and CalcStep).
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(5 * VL.size() + 2));
+  // Allocate space for 5 lists (Vars, Inits, Updates, Finals), 2 expressions
+  // (Step and CalcStep), list of used expression + step.
+  void *Mem =
+      C.Allocate(totalSizeToAlloc<Expr *>(5 * VL.size() + 2 + VL.size() + 1));
   OMPLinearClause *Clause = new (Mem) OMPLinearClause(
       StartLoc, LParenLoc, Modifier, ModifierLoc, ColonLoc, EndLoc, VL.size());
   Clause->setVarRefs(VL);
@@ -449,6 +457,8 @@ OMPLinearClause *OMPLinearClause::Create(
             nullptr);
   std::fill(Clause->getUpdates().end(), Clause->getUpdates().end() + VL.size(),
             nullptr);
+  std::fill(Clause->getUsedExprs().begin(), Clause->getUsedExprs().end(),
+            nullptr);
   Clause->setStep(Step);
   Clause->setCalcStep(CalcStep);
   Clause->setPreInitStmt(PreInit);
@@ -458,12 +468,19 @@ OMPLinearClause *OMPLinearClause::Create(
 
 OMPLinearClause *OMPLinearClause::CreateEmpty(const ASTContext &C,
                                               unsigned NumVars) {
-  // Allocate space for 4 lists (Vars, Inits, Updates, Finals) and 2 expressions
-  // (Step and CalcStep).
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(5 * NumVars + 2));
+  // Allocate space for 5 lists (Vars, Inits, Updates, Finals), 2 expressions
+  // (Step and CalcStep), list of used expression + step.
+  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(5 * NumVars + 2 + NumVars  +1));
   return new (Mem) OMPLinearClause(NumVars);
 }
 
+OMPClause::child_range OMPLinearClause::used_children() {
+  // Range includes only non-nullptr elements.
+  return child_range(
+      reinterpret_cast<Stmt **>(getUsedExprs().begin()),
+      reinterpret_cast<Stmt **>(llvm::find(getUsedExprs(), nullptr)));
+}
+
 OMPAlignedClause *
 OMPAlignedClause::Create(const ASTContext &C, SourceLocation StartLoc,
                          SourceLocation LParenLoc, SourceLocation ColonLoc,
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 4ac87469bf4..49c7c3aca14 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -12724,6 +12724,7 @@ static bool FinishOpenMPLinearClause(OMPLinearClause &Clause, DeclRefExpr *IV,
   // Walk the vars and build update/final expressions for the CodeGen.
   SmallVector<Expr *, 8> Updates;
   SmallVector<Expr *, 8> Finals;
+  SmallVector<Expr *, 8> UsedExprs;
   Expr *Step = Clause.getStep();
   Expr *CalcStep = Clause.getCalcStep();
   // OpenMP [2.14.3.7, linear clause]
@@ -12799,16 +12800,24 @@ static bool FinishOpenMPLinearClause(OMPLinearClause &Clause, DeclRefExpr *IV,
     if (!Update.isUsable() || !Final.isUsable()) {
       Updates.push_back(nullptr);
       Finals.push_back(nullptr);
+      UsedExprs.push_back(nullptr);
       HasErrors = true;
     } else {
       Updates.push_back(Update.get());
       Finals.push_back(Final.get());
+      if (!Info.first)
+        UsedExprs.push_back(SimpleRefExpr);
     }
     ++CurInit;
     ++CurPrivate;
   }
+  if (Expr *S = Clause.getStep())
+    UsedExprs.push_back(S);
+  // Fill the remaining part with the nullptr.
+  UsedExprs.append(Clause.varlist_size() + 1 - UsedExprs.size(), nullptr);
   Clause.setUpdates(Updates);
   Clause.setFinals(Finals);
+  Clause.setUsedExprs(UsedExprs);
   return HasErrors;
 }
 
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 4b6775de055..52ea1bf4a04 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -12736,6 +12736,10 @@ void OMPClauseReader::VisitOMPLinearClause(OMPLinearClause *C) {
   C->setFinals(Vars);
   C->setStep(Record.readSubExpr());
   C->setCalcStep(Record.readSubExpr());
+  Vars.clear();
+  for (unsigned I = 0; I != NumVars + 1; ++I)
+    Vars.push_back(Record.readSubExpr());
+  C->setUsedExprs(Vars);
 }
 
 void OMPClauseReader::VisitOMPAlignedClause(OMPAlignedClause *C) {
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 10946f9b0d9..9a1ebffdc92 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -6846,6 +6846,8 @@ void OMPClauseWriter::VisitOMPLinearClause(OMPLinearClause *C) {
   }
   Record.AddStmt(C->getStep());
   Record.AddStmt(C->getCalcStep());
+  for (auto *VE : C->used_expressions())
+    Record.AddStmt(VE);
 }
 
 void OMPClauseWriter::VisitOMPAlignedClause(OMPAlignedClause *C) {