[DebugInfo][RemoveDIs] "Final" cleanup for non-instr debug-info (#79121)

Here's a raft of minor fixes for the RemoveDIs project that's replacing
dbg.value intrinsics with DPValue objects, all IMO trivial:
 * When inserting functions or blocks and calling setIsNewDbgInfoFormat,
   do that after setting the Parent pointer, just in case conversion from
   (or to) dbg.value mode is triggered.
 * When transferring DPValues from an empty range in a splice call, don't
   transfer if there are no DPValues attached to the source block at all.
 * stripNonLineTableDebugInfo should drop DPValues.
 * In insertBefore, don't try to transfer DPValues if there aren't any.

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 53cbf01..d8c1b0d 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -892,6 +892,9 @@ bool llvm::stripNonLineTableDebugInfo(Module &M) {
         // Strip heapallocsite attachments, they point into the DIType system.
         if (I.hasMetadataOtherThanDebugLoc())
           I.setMetadata("heapallocsite", nullptr);
+
+        // Strip any DPValues attached.
+        I.dropDbgValues();
       }
     }
   }