Modify transformations to not break parallel regions

lib/Transforms/Scalar/JumpThreading.cpp

@@ -713,8 +713,9 @@ bool JumpThreadingPass::ProcessBlock(BasicBlock *BB) {
   // predecessors of our predecessor block.
   if (BasicBlock *SinglePred = BB->getSinglePredecessor()) {
     const TerminatorInst *TI = SinglePred->getTerminator();
-    if (!TI->isExceptional() && TI->getNumSuccessors() == 1 &&
-        SinglePred != BB && !hasAddressTakenAndUsed(BB)) {
+    if (!TI->isExceptional() && !TI->isParallelismRelated() &&
+        TI->getNumSuccessors() == 1 && SinglePred != BB &&
+        !hasAddressTakenAndUsed(BB)) {
       // If SinglePred was a loop header, BB becomes one.
       if (LoopHeaders.erase(SinglePred))
         LoopHeaders.insert(BB);
@@ -1955,6 +1956,6 @@ bool JumpThreadingPass::TryToUnfoldSelectInCurrBB(BasicBlock *BB) {
       return true;
     }
   }
-  
+
   return false;
 }

lib/Transforms/Scalar/SCCP.cpp

@@ -581,6 +581,12 @@ void SCCPSolver::getFeasibleSuccessors(TerminatorInst &TI,
     return;
   }
 
+  if (TI.isParallelismRelated()) {
+    // Mark all destinations executable!
+    Succs.assign(TI.getNumSuccessors(), true);
+    return;
+  }
+
 #ifndef NDEBUG
   dbgs() << "Unknown terminator instruction: " << TI << '\n';
 #endif
@@ -637,6 +643,9 @@ bool SCCPSolver::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
   if (isa<IndirectBrInst>(TI))
     return true;
 
+  if (TI->isParallelismRelated())
+    return true;
+
 #ifndef NDEBUG
   dbgs() << "Unknown terminator instruction: " << *TI << '\n';
 #endif

lib/Transforms/Utils/BasicBlockUtils.cpp

@@ -107,6 +107,9 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DominatorTree *DT,
   // Don't break unwinding instructions.
   if (PredBB->getTerminator()->isExceptional())
     return false;
+  // Don't break parallel tasks.
+  if (PredBB->getTerminator()->isParallelismRelated())
+    return false;
 
   succ_iterator SI(succ_begin(PredBB)), SE(succ_end(PredBB));
   BasicBlock *OnlySucc = BB;