More fixes for RC3

llvm/lib/Transforms/Instrumentation/CilkSanitizer.cpp

@@ -1060,6 +1060,7 @@ static void setupBlock(BasicBlock *BB, DominatorTree *DT, LoopInfo *LI,
   // Partition the predecessors of the landing pad.
   for (BasicBlock *Pred : predecessors(BB)) {
     if (isa<DetachInst>(Pred->getTerminator()) ||
+        isa<ReattachInst>(Pred->getTerminator()) ||
         isDetachedRethrow(Pred->getTerminator()))
       DetachPreds.push_back(Pred);
     else if (isTaskFrameResume(Pred->getTerminator()))

llvm/lib/Transforms/Instrumentation/ComprehensiveStaticInstrumentation.cpp

@@ -773,6 +773,7 @@ static void setupBlock(BasicBlock *BB, const TargetLibraryInfo *TLI,
   // Partition the predecessors of the landing pad.
   for (BasicBlock *Pred : predecessors(BB)) {
     if (isa<DetachInst>(Pred->getTerminator()) ||
+        isa<ReattachInst>(Pred->getTerminator()) ||
         isDetachedRethrow(Pred->getTerminator()))
       DetachPreds.push_back(Pred);
     else if (isTaskFrameResume(Pred->getTerminator()))

llvm/lib/Transforms/Utils/BasicBlockUtils.cpp

@@ -508,17 +508,41 @@ BasicBlock *llvm::SplitEdge(BasicBlock *BB, BasicBlock *Succ, DominatorTree *DT,
   // block.
   assert(BB->getTerminator()->getNumSuccessors() == 1 &&
          "Should have a single succ!");
-  BasicBlock *NewBB = SplitBlock(BB, BB->getTerminator(), DT, LI, MSSAU);
-  if (SyncInst *OldSI = dyn_cast<SyncInst>(NewBB->getTerminator())) {
-    // Make sure the original BB is terminated by the sync.
-    SyncInst *SI = SyncInst::Create(NewBB, OldSI->getSyncRegion(),
-                                    BB->getTerminator());
-    BranchInst::Create(Succ, OldSI);
-    SI->setDebugLoc(OldSI->getDebugLoc());
-    BB->getTerminator()->eraseFromParent();
-    OldSI->eraseFromParent();
+  if (SyncInst *OldSI = dyn_cast<SyncInst>(BB->getTerminator())) {
+    // Insert a new basic block after BB.
+    BasicBlock *NewBB =
+        BasicBlock::Create(BB->getContext(), BB->getName() + ".split",
+                           BB->getParent(), BB->getNextNode());
+    // Terminate that block with an unconditional branch to Succ.
+    BranchInst::Create(Succ, NewBB);
+    // Update the successor of the sync instruction to be NewBB.
+    OldSI->setSuccessor(0, NewBB);
+    // Update any PHI ndes in Succ.
+    NewBB->replaceSuccessorsPhiUsesWith(BB, NewBB);
+
+    // The new block lives in whichever loop the old one did. This preserves
+    // LCSSA as well, because we force the split point to be after any PHI
+    // nodes.
+    if (LI)
+      if (Loop *L = LI->getLoopFor(BB))
+        L->addBasicBlockToLoop(NewBB, *LI);
+
+    if (DT)
+      // Old dominates New. New node dominates all other nodes dominated by Old.
+      if (DomTreeNode *OldNode = DT->getNode(BB)) {
+        std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
+
+        DomTreeNode *NewNode = DT->addNewBlock(NewBB, BB);
+        for (DomTreeNode *I : Children)
+          DT->changeImmediateDominator(I, NewNode);
+      }
+
+    // Note: We don't need to update MSSA in this case, because the sync
+    // instruction remains in the original basic block.
+    return NewBB;
+  } else {
+    return SplitBlock(BB, BB->getTerminator(), DT, LI, MSSAU);
   }
-  return NewBB;
 }
 
 unsigned

llvm/lib/Transforms/Utils/LoopSimplify.cpp

@@ -544,7 +544,8 @@ static bool simplifyOneLoop(Loop *L, SmallVectorImpl<Loop *> &Worklist,
   if (Preheader && isa<SyncInst>(Preheader->getTerminator())) {
     LLVM_DEBUG(dbgs()
                << "LoopSimplify: Splitting sync-terminated preheader.\n");
-    SplitEdge(Preheader, L->getHeader(), DT, LI);
+    SplitEdge(Preheader, L->getHeader(), DT, LI, MSSAU);
+    Changed = true;
     Preheader = L->getLoopPreheader();
   }
 

llvm/test/Transforms/Tapir/csi-detach-continue-split.ll

@@ -0,0 +1,67 @@
+; Check that the CSI pass properly splits the predecessors of a detach-continuation block.
+;
+; RUN: opt < %s -csi -S -o - | FileCheck %s
+; RUN: opt < %s -passes='csi' -S -o - | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: argmemonly nounwind willreturn
+declare token @llvm.syncregion.start() #0
+
+define dso_local void @QuadNode_addIntersections() local_unnamed_addr #1 {
+entry:
+  %syncreg.i28 = tail call token @llvm.syncregion.start()
+  br i1 undef, label %if.then.tf, label %if.else
+
+if.then.tf:                                       ; preds = %entry
+  detach within %syncreg.i28, label %det.achd, label %det.cont.tf
+
+det.achd:                                         ; preds = %if.then.tf
+  unreachable
+
+det.cont.tf:                                      ; preds = %if.then.tf
+  detach within %syncreg.i28, label %det.achd1.tf.tf.tf, label %if.end
+
+; CHECK: det.cont.tf:
+; CHECK: detach within %syncreg.i28, label %[[DETACHED:.+]], label %[[CONTINUE:.+]]
+
+; CHECK: [[CONTINUE]]:
+; CHECK-NEXT: call void @__csi_detach_continue(
+; CHECK-NEXT: br label %if.end
+
+det.achd1.tf.tf.tf:                               ; preds = %det.cont.tf
+  br label %det.achd1.tf.tf.tf.tf
+
+det.achd1.tf.tf.tf.tf:                            ; preds = %det.achd1.tf.tf.tf
+  %tf.i = tail call token @llvm.taskframe.create()
+  %syncreg.i = tail call token @llvm.syncregion.start() #2
+  reattach within %syncreg.i28, label %if.end
+
+; CHECK: [[DETACHED]]:
+; CHECK: reattach within %syncreg.i28, label %[[CONTINUE]]
+
+if.else:                                          ; preds = %entry
+  sync within %syncreg.i28, label %if.end
+
+; CHECK: if.else:
+; CHECK: sync within %syncreg.i28, label %[[SYNC_SPLIT:.+]]
+
+; CHECK: [[SYNC_SPLIT]]:
+; CHECK: call void @__csi_after_sync(
+; CHECK: br label %if.end
+
+if.end:                                           ; preds = %if.else, %det.achd1.tf.tf.tf.tf, %det.cont.tf
+  unreachable
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare token @llvm.taskframe.create() #0
+
+attributes #0 = { argmemonly nounwind willreturn }
+attributes #1 = { "use-soft-float"="false" }
+attributes #2 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 10.0.1 (git@github.com:OpenCilk/opencilk-project.git 94a2a3eb6c9f8dd53def6e21c5ab8ff45acb586f)"}