[TapirTaskInfo] Fix the check for when a block is simply enclosed by …

…a task to handle unreachable blocks.

llvm/include/llvm/Analysis/TapirTaskInfo.h

@@ -859,7 +859,11 @@ class Task {
   /// Returns true if this task encloses basic block BB simply, that is, without
   /// checking any shared EH exits of this task.
   bool simplyEncloses(const BasicBlock *BB) const {
-    return DomTree.dominates(getEntry(), BB);
+    // DomTree.dominates(getEntry(), BB) will return true if BB is not reachable
+    // and getEntry() is reachable.  This method should return that BB is not
+    // simply enclosed in that case.
+    return DomTree.isReachableFromEntry(BB) &&
+           DomTree.dominates(getEntry(), BB);
   }
 
   /// Return true if specified task encloses basic block BB.

llvm/test/Transforms/Tapir/unlink-unreachable-detach-unwind.ll

@@ -0,0 +1,81 @@
+; Check that unlinking a task from its unwind destination handles
+; unreachable blocks correctly.
+;
+; RUN: opt < %s -passes="tapir2target" -use-opencilk-runtime-bc=false -debug-abi-calls -S | FileCheck %s
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-apple-macosx13.0.0"
+
+define void @_ZN9LAMMPS_NS6Verlet14run_stencil_mdEiPNSt3__16vectorIiNS1_9allocatorIiEEEES6_PiS7_PPdS9_() personality ptr null {
+entry:
+  %syncreg = call token @llvm.syncregion.start()
+  %syncreg359 = call token @llvm.syncregion.start()
+  %syncreg461 = call token @llvm.syncregion.start()
+  %syncreg783 = call token @llvm.syncregion.start()
+  %syncreg1089 = call token @llvm.syncregion.start()
+  br label %pfor.detach470
+
+for.body87:                                       ; No predecessors!
+  %call116 = invoke i64 null(ptr null, ptr null)
+          to label %invoke.cont115 unwind label %lpad651
+
+invoke.cont115:                                   ; preds = %for.body87
+  store i64 %call116, ptr null, align 8
+  br label %for.cond131
+
+for.cond131:                                      ; preds = %for.cond131, %invoke.cont115
+  br label %for.cond131
+
+pfor.body.entry:                                  ; preds = %pfor.inc273
+  %syncreg223 = call token @llvm.syncregion.start()
+  reattach within %syncreg, label %pfor.inc273
+
+pfor.inc273:                                      ; preds = %pfor.inc273, %pfor.body.entry
+  detach within %syncreg, label %pfor.body.entry, label %pfor.inc273 unwind label %lpad651
+
+pfor.detach470:                                   ; preds = %pfor.detach470, %entry
+  detach within none, label %pfor.body.entry472, label %pfor.detach470 unwind label %lpad651
+
+pfor.body.entry472:                               ; preds = %pfor.detach470
+  %syncreg481 = call token @llvm.syncregion.start()
+  br label %pfor.detach490
+
+pfor.detach490:                                   ; preds = %pfor.detach490, %pfor.body.entry472
+  br label %pfor.detach490
+
+lpad651:                                          ; preds = %pfor.inc907, %pfor.detach470, %pfor.inc273, %for.body87
+  %0 = landingpad { ptr, i32 }
+          cleanup
+  resume { ptr, i32 } zeroinitializer
+
+pfor.body.entry799:                               ; preds = %pfor.inc907
+  %syncreg843 = call token @llvm.syncregion.start()
+  reattach within none, label %pfor.inc907
+
+pfor.inc907:                                      ; preds = %pfor.inc907, %pfor.body.entry799
+  detach within none, label %pfor.body.entry799, label %pfor.inc907 unwind label %lpad651
+}
+
+; CHECK: define void @_ZN9LAMMPS_NS6Verlet14run_stencil_mdEiPNSt3__16vectorIiNS1_9allocatorIiEEEES6_PiS7_PPdS9_()
+
+; Outlining the task detached at pfor.detach470 should not delete for.body87 and leave the use of %call116 in invoke.cont115 without its definition.
+
+; CHECK: for.body87:
+; CHECK-NEXT: %call116 = invoke i64 null(ptr null, ptr null)
+; CHECK-NEXT: to label %invoke.cont115 unwind label %lpad651
+
+; CHECK: invoke.cont115:
+; CHECK-NEXT: store i64 %call116, ptr null, align 8
+
+; CHECK: pfor.detach470:
+; CHECK-NOT: detach within
+; CHECK: invoke fastcc void @_ZN9LAMMPS_NS6Verlet14run_stencil_mdEiPNSt3__16vectorIiNS1_9allocatorIiEEEES6_PiS7_PPdS9_.outline_pfor.body.entry472.otd1()
+; CHECK-NEXT: to label %pfor.detach470 unwind label %lpad651
+
+; Function Attrs: nounwind willreturn memory(argmem: readwrite)
+declare token @llvm.syncregion.start() #0
+
+; uselistorder directives
+uselistorder ptr null, { 1, 2, 3, 4, 5, 6, 0 }
+uselistorder ptr @llvm.syncregion.start, { 7, 6, 5, 4, 3, 2, 1, 0 }
+
+attributes #0 = { nounwind willreturn memory(argmem: readwrite) }