From b2ef596c415e42d79470a8356f7816aa4989e34c Mon Sep 17 00:00:00 2001
From: Bruce Forstall <brucefo@microsoft.com>
Date: Thu, 11 Jan 2024 13:38:20 -0800
Subject: [PATCH] Preserve debug info for merged returns

If converting a void GT_RETURN to a branch to a merged return
block, keep it as a GT_NOP if it has debug info that should
be preserved.
---
 src/coreclr/jit/morph.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/coreclr/jit/morph.cpp b/src/coreclr/jit/morph.cpp
index eff3d4ee413740..5e517a96c8aec3 100644
--- a/src/coreclr/jit/morph.cpp
+++ b/src/coreclr/jit/morph.cpp
@@ -14189,6 +14189,7 @@ void Compiler::fgMergeBlockReturn(BasicBlock* block)
             fgAddRefPred(genReturnBB, block);
             fgReturnCount--;
         }
+
         if (genReturnLocal != BAD_VAR_NUM)
         {
             // replace the GT_RETURN node to be a STORE_LCL_VAR that stores the return value into genReturnLocal.
@@ -14243,7 +14244,15 @@ void Compiler::fgMergeBlockReturn(BasicBlock* block)
             noway_assert(ret->TypeGet() == TYP_VOID);
             noway_assert(ret->gtGetOp1() == nullptr);
 
-            fgRemoveStmt(block, lastStmt);
+            if (opts.compDbgCode && lastStmt->GetDebugInfo().IsValid())
+            {
+                // We can't remove the return as it might remove a sequence point. Convert it to a NOP.
+                ret->gtBashToNOP();
+            }
+            else
+            {
+                fgRemoveStmt(block, lastStmt);
+            }
         }
 
         JITDUMP("\nUpdate " FMT_BB " to jump to common return block.\n", block->bbNum);