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

[ABataev]

Summary

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

[ABataev]

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Ping

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Better to fix this before the next release.

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clang/include/clang/Basic/DiagnosticSemaKinds.td

 def err_omp_instantiation_not_supported
     : Error<"instantiation of '%0' not supported yet">;
 def err_omp_adjust_arg_multiple_clauses : Error<
   "'adjust_arg' argument %0 used in multiple clauses">;
 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 {
 // Objective-C related result type compatibility
 def warn_related_result_type_compatibility_class : Warning<
   "method is expected to return an instance of its class type "
   "%diff{$, but is declared to return $|"
   ", but is declared to return different type}0,1">;

clang/include/clang/Sema/Sema.h

public:
   void
   checkDeclIsAllowedInOpenMPTarget(Expr *E, Decl *D,
                                    SourceLocation IdLoc = SourceLocation());
   /// Finishes analysis of the deferred functions calls that may be declared as
   /// host/nohost during device/host compilation.
   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();
   }
   /// Return true inside OpenMP target region.
   bool isInOpenMPTargetExecutionDirective() const;
 
   /// Return the number of captured regions created for an OpenMP directive.

clang/lib/Sema/SemaOpenMP.cpp

struct SharingMapTy {
     /// First argument (Expr *) contains optional argument of the
     /// 'ordered' clause, the second one is true if the regions has 'ordered'
     /// clause, false otherwise.
     llvm::Optional<std::pair<const Expr *, OMPOrderedClause *>> OrderedRegion;
     unsigned AssociatedLoops = 1;
     bool HasMutipleLoops = false;
     const Decl *PossiblyLoopCounter = nullptr;
     bool NowaitRegion = false;
+    bool UntiedRegion = false;
     bool CancelRegion = false;
     bool LoopStart = false;
     bool BodyComplete = false;
     SourceLocation PrevScanLocation;
     SourceLocation PrevOrderedLocation;
     SourceLocation InnerTeamsRegionLoc;
     /// Reference to the taskgroup task_reduction reference expression.
     Expr *TaskgroupReductionRef = nullptr;
public:
   }
   /// Returns true, if parent region is nowait (has associated
   /// 'nowait' clause), false - otherwise.
   bool isParentNowaitRegion() const {
     if (const SharingMapTy *Parent = getSecondOnStackOrNull())
       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())
       Parent->CancelRegion |= Cancel;
   }
   /// Return true if current region has inner cancel construct.
   bool isCancelRegion() const {
     const SharingMapTy *Top = getTopOfStackOrNull();
bool Sema::isOpenMPCapturedByRef(const ValueDecl *D, unsigned Level,
   return IsByRef;
 }
 
 unsigned Sema::getOpenMPNestingLevel() const {
   assert(getLangOpts().OpenMP);
   return DSAStack->getNestingLevel();
 }
 
+bool Sema::isInOpenMPTaskUntiedContext() const {
+  return isOpenMPTaskingDirective(DSAStack->getCurrentDirective()) &&
+         DSAStack->isUntiedRegion();
+}
+
 bool Sema::isInOpenMPTargetExecutionDirective() const {
   return (isOpenMPTargetExecutionDirective(DSAStack->getCurrentDirective()) &&
           !DSAStack->isClauseParsingMode()) ||
          DSAStack->hasDirective(
              [](OpenMPDirectiveKind K, const DeclarationNameInfo &,
                 SourceLocation) -> bool {
                return isOpenMPTargetExecutionDirective(K);
              },

 OMPClause *Sema::ActOnOpenMPNowaitClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
   DSAStack->setNowaitRegion();
   return new (Context) OMPNowaitClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPUntiedClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
+  DSAStack->setUntiedRegion();
   return new (Context) OMPUntiedClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPMergeableClause(SourceLocation StartLoc,
                                             SourceLocation EndLoc) {
   return new (Context) OMPMergeableClause(StartLoc, EndLoc);
 }
 

clang/lib/Sema/SemaType.cpp

if (getLangOpts().OpenCL) {
     VLADiag = diag::err_opencl_vla;
     VLAIsError = true;
   } else if (getLangOpts().C99) {
     VLADiag = diag::warn_vla_used;
     VLAIsError = false;
   } 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;
   }
 
   llvm::APSInt ConstVal(Context.getTypeSize(Context.getSizeType()));
   if (!ArraySize) {
     if (ASM == ArrayType::Star) {

clang/test/OpenMP/task_messages.cpp

#pragma omp task detach(evt) firstprivate(evt) // omp45-error {{unexpected OpenMP clause 'detach' in directive '#pragma omp task'}}
   return a + b;
 }
 
 int main(int argc, char **argv) {
   int a;
   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}}
   foo();
 #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}}
   foo();

 #pragma omp for reduction(+ : r)
   ++r;
 // expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'untied' clause}}
 #pragma omp task untied untied
   ++r;
 // 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;
   omp_event_handle_t &revt = sevt;
 #pragma omp task detach // omp45-error {{unexpected OpenMP clause 'detach' in directive '#pragma omp task'}} expected-error {{expected '(' after 'detach'}}
 #pragma omp task detach( // omp45-error {{unexpected OpenMP clause 'detach' in directive '#pragma omp task'}} expected-error {{expected expression}} expected-error {{expected ')'}} expected-note {{to match this '('}}
 #pragma omp task detach() // omp45-error {{unexpected OpenMP clause 'detach' in directive '#pragma omp task'}} expected-error {{expected expression}}
 #pragma omp task detach(a) // omp45-error {{unexpected OpenMP clause 'detach' in directive '#pragma omp task'}} omp50-error {{expected variable of the 'omp_event_handle_t' type, not 'int'}}

clang/test/OpenMP/taskloop_loop_messages.cpp

for (int j = 0; j < 10; j++) {
         }
       }
     }
   }
 }
 
 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++) {
     c[i] = a[i] + b[i];
     try {
       for (int j = 0; j < 10; ++j) {
         if (a[i] > b[j])
           throw a[i];

 
 #pragma omp parallel
 #pragma omp taskloop
   for (int i = 0; i < 10; ++i) {
     struct S {
       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() {
   S s(4);
 #pragma omp parallel
 #pragma omp taskloop lastprivate(s) firstprivate(s)
   for (int i = 0; i < 16; ++i)
     ;
 }