[llvm] Add missing nullptr check in LLVMGetFirstDbgRecord (PR #151101)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-ir

Author: Maxime Arthaud (arthaud)

<details>
<summary>Changes</summary>

I'm using the LLVM C bindings through the llvm-sys rust crate, and notice that LLVMGetFirstDbgRecord and LLVMGetLastDbgRecord are segfault-ing when called on instructions without debug markers. I found out it's missing a null pointer check. This PR fixes the issue.



---
Full diff: https://github.com/llvm/llvm-project/pull/151101.diff


1 Files Affected:

- (modified) llvm/lib/IR/Core.cpp (+4) 


``````````diff
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index f7ef4aa473ef5..56190545eb024 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -2984,6 +2984,8 @@ LLVMValueRef LLVMIsATerminatorInst(LLVMValueRef Inst) {
 
 LLVMDbgRecordRef LLVMGetFirstDbgRecord(LLVMValueRef Inst) {
   Instruction *Instr = unwrap<Instruction>(Inst);
+  if (!Instr->DebugMarker)
+    return nullptr;
   auto I = Instr->DebugMarker->StoredDbgRecords.begin();
   if (I == Instr->DebugMarker->StoredDbgRecords.end())
     return nullptr;
@@ -2992,6 +2994,8 @@ LLVMDbgRecordRef LLVMGetFirstDbgRecord(LLVMValueRef Inst) {
 
 LLVMDbgRecordRef LLVMGetLastDbgRecord(LLVMValueRef Inst) {
   Instruction *Instr = unwrap<Instruction>(Inst);
+  if (!Instr->DebugMarker)
+    return nullptr;
   auto I = Instr->DebugMarker->StoredDbgRecords.rbegin();
   if (I == Instr->DebugMarker->StoredDbgRecords.rend())
     return nullptr;

``````````

</details>


https://github.com/llvm/llvm-project/pull/151101