[llvm] [OMPIRBuilder] Don't discard the debug record from entry block. (PR #135161)

[Abid Qadeer via llvm-commits]

https://github.com/abidh created https://github.com/llvm/llvm-project/pull/135161

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.

>From a8504737273a7a252370f2fdc0e0cea54cd94bfe Mon Sep 17 00:00:00 2001
From: Abid Qadeer <haqadeer at amd.com>
Date: Thu, 10 Apr 2025 11:32:29 +0100
Subject: [PATCH] [OMPIRBuilder] Don't discard the debug record from entry
 block.

When we get a function back from CodeExtractor, we disard 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.
---
 llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

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());
       }