[OMPIRBuilder] Don't discard the debug record from entry block.

[abidh]

When we get a function back from CodeExtractor, we discard its entry block after coping its instructions into the entry block we prepared. While copying the instructions, the terminator is discarded for obvious reasons. But if there were some debug values attached to the terminator, those are useful and needs to be copied.

[llvmbot]

@llvm/pr-subscribers-mlir-llvm
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-flang-openmp

Author: Abid Qadeer (abidh)

Changes

When we get a function back from CodeExtractor, we discard its entry block after coping its instructions into the entry block we prepared. While copying the instructions, the terminator is discarded for obvious reasons. But if there were some debug values attached to the terminator, those are useful and needs to be copied.

---

Full diff: https://github.com/llvm/llvm-project/pull/135161.diff

1 Files Affected:

• (modified) llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp (+6-1)

diff --git a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
index 28662efc02882..f946fab42ca7a 100644
--- a/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
+++ b/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
@@ -788,8 +788,13 @@ void OpenMPIRBuilder::finalize(Function *Fn) {
         Instruction &I = *It;
         It++;
 
-        if (I.isTerminator())
+        if (I.isTerminator()) {
+          // Absorb any debug value that terminator may have
+          if (OI.EntryBB->getTerminator())
+            OI.EntryBB->getTerminator()->adoptDbgRecords(
+                &ArtificialEntry, I.getIterator(), false);
           continue;
+        }
 
         I.moveBeforePreserving(*OI.EntryBB, OI.EntryBB->getFirstInsertionPt());
       }

[Meinersbur]

Could you add a test so we do not regress in the future?

[abidh]

Could you add a test so we do not regress in the future?

Hi @Meinersbur

Thanks for taking a look. Although this change fixes a missing piece, there is currently no way to test it as CodeExtractor does not generate the debug info in the entry block. This is preparatory PR for the bigger changes I am working on to improve the debug info of the function generated by the CodeExtractor. The bigger PR will have the tests.

This piece was independent and self contained so I thought I will post it separately.

[abidh]

We can test this functionality now as #136016 has been merged. I have added a test and updated relevant clang tests.

[Meinersbur]

LGTM, thank you.