[llvm] 0338350 - [llvm-c] Add missing nullptr check in LLVMGetFirstDbgRecord (#151101)

[via llvm-commits]

Author: Maxime Arthaud
Date: 2025-10-05T08:01:19Z
New Revision: 0338350ccb506020529259427ec1c66ca6569749

URL: https://github.com/llvm/llvm-project/commit/0338350ccb506020529259427ec1c66ca6569749
DIFF: https://github.com/llvm/llvm-project/commit/0338350ccb506020529259427ec1c66ca6569749.diff

LOG: [llvm-c] Add missing nullptr check in LLVMGetFirstDbgRecord (#151101)

I'm using the LLVM C bindings through the llvm-sys rust crate, and
noticed 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.

Added: 
    

Modified: 
    llvm/lib/IR/Core.cpp
    llvm/tools/llvm-c-test/debuginfo.c

Removed: 
    


################################################################################
diff  --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
index 8b5965ba45a6d..df0c85b87ba60 100644
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -2994,6 +2994,8 @@ 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;
@@ -3002,6 +3004,8 @@ 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;

diff  --git a/llvm/tools/llvm-c-test/debuginfo.c b/llvm/tools/llvm-c-test/debuginfo.c
index 0f09c74a476bb..e376d82009be0 100644
--- a/llvm/tools/llvm-c-test/debuginfo.c
+++ b/llvm/tools/llvm-c-test/debuginfo.c
@@ -325,6 +325,13 @@ int llvm_test_dibuilder(void) {
   LLVMValueRef Phi2 = LLVMBuildPhi(Builder, I64, "p2");
   LLVMAddIncoming(Phi2, &Zero, &FooEntryBlock, 1);
 
+  // Test that LLVMGetFirstDbgRecord and LLVMGetLastDbgRecord return NULL for
+  // instructions without debug info.
+  LLVMDbgRecordRef Phi1FirstDbgRecord = LLVMGetFirstDbgRecord(Phi1);
+  assert(Phi1FirstDbgRecord == NULL);
+  LLVMDbgRecordRef Phi1LastDbgRecord = LLVMGetLastDbgRecord(Phi1);
+  assert(Phi1LastDbgRecord == NULL);
+
   // Insert a non-phi before the `ret` but not before the debug records to
   // test that works as expected.
   LLVMPositionBuilder(Builder, FooVarBlock, Ret);