[Cilk] Emit a diagnostic message, rather than fail an assert, when co…

…degen fails to emit a spawn.

Addresses issue #5

clang/lib/CodeGen/CGCilk.cpp

@@ -192,7 +192,7 @@ void CodeGenFunction::DetachScope::StartDetach() {
 }
 
 void CodeGenFunction::DetachScope::CleanupDetach() {
-  if (DetachCleanedUp)
+  if (!DetachStarted || DetachCleanedUp)
     return;
 
   // Pop the sync region for the detached task.
@@ -380,13 +380,6 @@ static const Stmt *IgnoreImplicitAndCleanups(const Stmt *S) {
   return Current;
 }
 
-static void FailedSpawnWarning(CodeGenFunction &CGF, SourceLocation SLoc) {
-  DiagnosticsEngine &Diags = CGF.CGM.getDiags();
-  unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Warning,
-                                          "Failed to produce spawn");
-  Diags.Report(SLoc, DiagID);
-}
-
 void CodeGenFunction::EmitCilkSpawnStmt(const CilkSpawnStmt &S) {
   // Handle spawning of calls in a special manner, to evaluate
   // arguments before spawn.
@@ -403,7 +396,7 @@ void CodeGenFunction::EmitCilkSpawnStmt(const CilkSpawnStmt &S) {
     // Finish the detach.
     if (IsSpawned) {
       if (!CurDetachScope->IsDetachStarted())
-        FailedSpawnWarning(*this, S.getBeginLoc());
+        FailedSpawnWarning(S.getBeginLoc());
       IsSpawned = false;
       PopDetachScope();
     }
@@ -441,7 +434,7 @@ LValue CodeGenFunction::EmitCilkSpawnExprLValue(const CilkSpawnExpr *E) {
   // Finish the detach.
   if (IsSpawned) {
     if (!CurDetachScope->IsDetachStarted())
-      FailedSpawnWarning(*this, E->getExprLoc());
+      FailedSpawnWarning(E->getExprLoc());
     IsSpawned = false;
     PopDetachScope();
   }

clang/lib/CodeGen/CGExpr.cpp

@@ -4646,8 +4646,8 @@ LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
       EmitStoreThroughLValue(RV, LV);
 
       // Finish the detach.
-      assert(CurDetachScope && CurDetachScope->IsDetachStarted() &&
-             "Processing _Cilk_spawn of expression did not produce a detach.");
+      if (!(CurDetachScope && CurDetachScope->IsDetachStarted()))
+        FailedSpawnWarning(E->getRHS()->getExprLoc());
       PopDetachScope();
       IsSpawned = false;
 

clang/lib/CodeGen/CGExprAgg.cpp

@@ -890,8 +890,8 @@ void AggExprEmitter::VisitCilkSpawnExpr(CilkSpawnExpr *E) {
   Visit(E->getSpawnedExpr());
 
   // Pop the detach scope
-  assert(CGF.IsSpawned && CGF.CurDetachScope->IsDetachStarted() &&
-         "Processing _Cilk_spawn of expression did not produce a detach.");
+  if (!(CGF.IsSpawned && CGF.CurDetachScope->IsDetachStarted()))
+    CGF.FailedSpawnWarning(E->getExprLoc());
   CGF.IsSpawned = false;
   CGF.PopDetachScope();
 }
@@ -1192,8 +1192,8 @@ void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
     Visit(E->getRHS());
     CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
     if (CGF.IsSpawned) {
-      assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-             "Processing _Cilk_spawn of expression did not produce a detach.");
+      if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+        CGF.FailedSpawnWarning(E->getRHS()->getExprLoc());
       CGF.IsSpawned = false;
       CGF.PopDetachScope();
     }
@@ -1217,8 +1217,8 @@ void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
   EmitFinalDestCopy(E->getType(), LHS);
 
   if (CGF.IsSpawned) {
-    assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-           "Processing _Cilk_spawn of expression did not produce a detach.");
+    if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+      CGF.FailedSpawnWarning(E->getRHS()->getExprLoc());
     CGF.IsSpawned = false;
     CGF.PopDetachScope();
   }

clang/lib/CodeGen/CGExprComplex.cpp

@@ -133,8 +133,8 @@ class ComplexExprEmitter
     CGF.PushDetachScope();
     ComplexPairTy C = Visit(CSE->getSpawnedExpr());
     if (DoSpawnedInit) {
-      assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-             "Processing _Cilk_spawn of expression did not produce detach.");
+      if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+        CGF.FailedSpawnWarning(CSE->getExprLoc());
       LValue LV = LValueToSpawnInit;
       EmitStoreOfComplex(C, LV, /*init*/ true);
 
@@ -1022,8 +1022,8 @@ LValue ComplexExprEmitter::EmitBinAssignLValue(const BinaryOperator *E,
     EmitStoreOfComplex(Val, LHS, /*isInit*/ false);
 
     // Finish the detach.
-    assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-           "Processing _Cilk_spawn of expression did not produce detach.");
+    if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+      CGF.FailedSpawnWarning(E->getRHS()->getExprLoc());
     CGF.IsSpawned = false;
     CGF.PopDetachScope();
 

clang/lib/CodeGen/CGExprScalar.cpp

@@ -464,9 +464,9 @@ class ScalarExprEmitter
     CGF.IsSpawned = true;
     CGF.PushDetachScope();
     Value *V = Visit(CSE->getSpawnedExpr());
+    if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+      CGF.FailedSpawnWarning(CSE->getExprLoc());
     if (DoSpawnedInit) {
-      assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-             "Processing _Cilk_spawn of expression did not produce detach.");
       LValue LV = LValueToSpawnInit;
       CGF.EmitNullabilityCheck(LV, V, CSE->getExprLoc());
       CGF.EmitStoreThroughLValue(RValue::get(V), LV, true);
@@ -3974,8 +3974,8 @@ Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
         CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS);
 
       // Finish the detach.
-      assert(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted() &&
-             "Processing _Cilk_spawn of expression did not produce detach.");
+      if (!(CGF.CurDetachScope && CGF.CurDetachScope->IsDetachStarted()))
+        CGF.FailedSpawnWarning(E->getRHS()->getExprLoc());
       CGF.IsSpawned = false;
       CGF.PopDetachScope();
 

clang/lib/CodeGen/CGStmt.cpp

@@ -1145,9 +1145,9 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
     CurDetachScope->CleanupDetach();
   cleanupScope.ForceCleanup();
   if (IsSpawned) {
+    if (!(CurDetachScope && CurDetachScope->IsDetachStarted()))
+      FailedSpawnWarning(RV->getExprLoc());
     // Pop the detach scope
-    assert(IsSpawned && CurDetachScope->IsDetachStarted() &&
-           "Processing _Cilk_spawn of expression did not produce a detach.");
     IsSpawned = false;
     PopDetachScope();
   }

clang/lib/CodeGen/CodeGenFunction.h

@@ -1382,6 +1382,14 @@ class CodeGenFunction : public CodeGenTypeCache {
     delete CurDetachScope;
   }
 
+  /// Produce a warning that we failed to emit a spawn.
+  void FailedSpawnWarning(SourceLocation SLoc) {
+    DiagnosticsEngine &Diags = CGM.getDiags();
+    unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Warning,
+                                            "Failed to emit spawn");
+    Diags.Report(SLoc, DiagID);
+  }
+
   // RAII for automatically popping detach scopes at the end of code-generating
   // an expression.
   class DetachScopeRAII {
@@ -1396,7 +1404,7 @@ class CodeGenFunction : public CodeGenTypeCache {
         return;
       CGF.PopDetachScope();
       assert(CGF.CurDetachScope == StartingDetachScope &&
-             "Unexpected detach scope after processing AtomicExpr");
+             "Unexpected detach scope");
       CGF.IsSpawned = false;
     }
   };

clang/test/Cilk/spawn-expr.c

@@ -0,0 +1,15 @@
+// Check the spawning of builtins.
+//
+// RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -fopencilk -verify -ftapir=none -S -emit-llvm -o - | FileCheck %s
+
+int g(int);
+
+int f() {
+  int x = _Cilk_spawn 0; // expected-warning {{Failed to emit spawn}}
+  g(_Cilk_spawn 7); // expected-warning {{Failed to emit spawn}}
+  return _Cilk_spawn 1; // expected-warning {{no parallelism from a '_Cilk_spawn' in a return statement}} expected-warning {{Failed to emit spawn}}
+}
+
+// CHECK-LABEL: define {{.*}}i32 @f(
+// CHECK-NOT: detach
+