[OPENMP]Fix PR49366: crash on VLAs in task untied regions.

We need to capture the local variables into a record in task untied
regions but clang does not support record with VLA data members.

Differential Revision: https://reviews.llvm.org/D99436

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10893,6 +10893,8 @@ def err_omp_clause_requires_dispatch_construct : Error<
   "'%0' clause requires 'dispatch' context selector">;
 def err_omp_append_args_with_varargs : Error<
   "'append_args' is not allowed with varargs functions">;
+def err_openmp_vla_in_task_untied : Error<
+  "variable length arrays are not supported in OpenMP tasking regions with 'untied' clause">;
 } // end of OpenMP category
 
 let CategoryName = "Related Result Type Issue" in {

clang/include/clang/Sema/Sema.h

@@ -10688,6 +10688,10 @@ public:
   void finalizeOpenMPDelayedAnalysis(const FunctionDecl *Caller,
                                      const FunctionDecl *Callee,
                                      SourceLocation Loc);
+
+  /// Return true if currently in OpenMP task with untied clause context.
+  bool isInOpenMPTaskUntiedContext() const;
+
   /// Return true inside OpenMP declare target region.
   bool isInOpenMPDeclareTargetContext() const {
     return !DeclareTargetNesting.empty();

clang/lib/Sema/SemaOpenMP.cpp

@@ -176,6 +176,7 @@ private:
     bool HasMutipleLoops = false;
     const Decl *PossiblyLoopCounter = nullptr;
     bool NowaitRegion = false;
+    bool UntiedRegion = false;
     bool CancelRegion = false;
     bool LoopStart = false;
     bool BodyComplete = false;
@@ -851,6 +852,15 @@ public:
       return Parent->NowaitRegion;
     return false;
   }
+  /// Marks current region as untied (it has a 'untied' clause).
+  void setUntiedRegion(bool IsUntied = true) {
+    getTopOfStack().UntiedRegion = IsUntied;
+  }
+  /// Return true if current region is untied.
+  bool isUntiedRegion() const {
+    const SharingMapTy *Top = getTopOfStackOrNull();
+    return Top ? Top->UntiedRegion : false;
+  }
   /// Marks parent region as cancel region.
   void setParentCancelRegion(bool Cancel = true) {
     if (SharingMapTy *Parent = getSecondOnStackOrNull())
@@ -2158,6 +2168,11 @@ unsigned Sema::getOpenMPNestingLevel() const {
   return DSAStack->getNestingLevel();
 }
 
+bool Sema::isInOpenMPTaskUntiedContext() const {
+  return isOpenMPTaskingDirective(DSAStack->getCurrentDirective()) &&
+         DSAStack->isUntiedRegion();
+}
+
 bool Sema::isInOpenMPTargetExecutionDirective() const {
   return (isOpenMPTargetExecutionDirective(DSAStack->getCurrentDirective()) &&
           !DSAStack->isClauseParsingMode()) ||
@@ -16232,6 +16247,7 @@ OMPClause *Sema::ActOnOpenMPNowaitClause(SourceLocation StartLoc,
 
 OMPClause *Sema::ActOnOpenMPUntiedClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
+  DSAStack->setUntiedRegion();
   return new (Context) OMPUntiedClause(StartLoc, EndLoc);
 }
 

clang/lib/Sema/SemaType.cpp

@@ -2458,6 +2458,9 @@ QualType Sema::BuildArrayType(QualType T, ArrayType::ArraySizeModifier ASM,
   } else if (isSFINAEContext()) {
     VLADiag = diag::err_vla_in_sfinae;
     VLAIsError = true;
+  } else if (getLangOpts().OpenMP && isInOpenMPTaskUntiedContext()) {
+    VLADiag = diag::err_openmp_vla_in_task_untied;
+    VLAIsError = true;
   } else {
     VLADiag = diag::ext_vla;
     VLAIsError = false;

clang/test/OpenMP/task_messages.cpp

@@ -173,7 +173,7 @@ int main(int argc, char **argv) {
   int &b = a;
   S sa;
   S &sb = sa;
-  int r;
+  int r; // expected-note {{declared here}}
 #pragma omp task { // expected-warning {{extra tokens at the end of '#pragma omp task' are ignored}}
   foo();
 #pragma omp task( // expected-warning {{extra tokens at the end of '#pragma omp task' are ignored}}
@@ -330,6 +330,12 @@ L2:
 // expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'mergeable' clause}}
 #pragma omp task mergeable mergeable
   ++r;
+// expected-error@+4 {{variable length arrays are not supported in OpenMP tasking regions with 'untied' clause}}
+// expected-note@+3 {{read of non-const variable 'r' is not allowed in a constant expression}}
+#pragma omp task untied
+  {
+    int array[r];
+  }
   volatile omp_event_handle_t evt;
   omp_event_handle_t sevt;
   const omp_event_handle_t cevt = evt;

clang/test/OpenMP/taskloop_loop_messages.cpp

@@ -691,7 +691,7 @@ void test_loop_break() {
 
 void test_loop_eh() {
   const int N = 100;
-  float a[N], b[N], c[N];
+  float a[N], b[N], c[N]; // expected-note {{declared here}}
 #pragma omp parallel
 #pragma omp taskloop
   for (int i = 0; i < 10; i++) {
@@ -729,6 +729,13 @@ void test_loop_eh() {
       void g() { throw 0; }
     };
   }
+// expected-error@+5 {{variable length arrays are not supported in OpenMP tasking regions with 'untied' clause}}
+// expected-note@+4 {{read of non-constexpr variable 'c' is not allowed in a constant expression}}
+#pragma omp taskloop untied
+  {
+  for (int i = 0; i < 10; ++i)
+    int array[(int)c[0]];
+  }
 }
 
 void test_loop_firstprivate_lastprivate() {