[OMPIRBuilder] Prevent dangling InsertPt in IRBuilder.

[abidh]

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

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

[llvmbot]

@llvm/pr-subscribers-flang-openmp

Author: Abid Qadeer (abidh)

Changes

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

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

---

Full diff: https://github.com/llvm/llvm-project/pull/148887.diff

1 Files Affected:

• (modified) llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp (+6-2)

diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index 4f08ea97378c2..a3e0d7c89357b 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/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();
   };

[tblah]

Thanks for fixing this. Is it possible to set no insert point? Like a nullptr. The insert points added here aren't really meaningful to anything that tries to use them.