[OMPIRBuilder] Prevent dangling InsertPt in IRBuilder.

There are places in PostOutlineCB callbacks where the instruction is
deleted while InsertPt in the IRBuilder pointed to it causing dangling
InsertPt. This PR fixes that by ensuring that the InsertPt is always
valid.

This fixes the sanitizer fail that was seen in llvm#148284.

Author: abidh

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -2155,9 +2155,11 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::createTask(
       OutlinedFn.getArg(1)->replaceUsesWithIf(
           Shareds, [Shareds](Use &U) { return U.getUser() != Shareds; });
     }
-
-    for (Instruction *I : llvm::reverse(ToBeDeleted))
+    for (Instruction *I : llvm::reverse(ToBeDeleted)) {
+      if (I->getIterator() == Builder.GetInsertPoint())
+        Builder.SetInsertPoint(I->getParent());
       I->eraseFromParent();
+    }
   };
 
   addOutlineInfo(std::move(OI));
@@ -7714,6 +7716,7 @@ OpenMPIRBuilder::InsertPointOrErrorTy OpenMPIRBuilder::emitTargetTask(
       Builder.CreateCall(TaskFn, {Ident, ThreadID, TaskData});
     }
 
+    Builder.SetInsertPoint(StaleCI->getParent());
     StaleCI->eraseFromParent();
     for (Instruction *I : llvm::reverse(ToBeDeleted))
       I->eraseFromParent();
@@ -9511,6 +9514,7 @@ OpenMPIRBuilder::createTeams(const LocationDescription &Loc,
                            omp::RuntimeFunction::OMPRTL___kmpc_fork_teams),
                        Args);
 
+    Builder.SetInsertPoint(StaleCI->getParent());
     for (Instruction *I : llvm::reverse(ToBeDeleted))
       I->eraseFromParent();
   };