[MergeFuncs/CFI] Ensure all type metadata is propogated for CFI (#88218)

I noticed that we weren't propagating ALL type metadata that was
attached to CFI functions:

# BEFORE

```
; Function Attrs: minsize nounwind optsize ssp uwtable(sync)
define internal void @foo(ptr nocapture noundef readonly %0) #0 !dbg !62311 !type !34028 !type !34029 !type !34030
... fn merging
; Function Attrs: minsize nounwind optsize ssp uwtable(sync)
define internal void @foo(ptr nocapture noundef readonly %0) #0 !type !34028
```

# AFTER

```
; Function Attrs: minsize nounwind optsize ssp uwtable(sync)
define internal void @foo(ptr nocapture noundef readonly %0) #0 !dbg !62311 !type !34028 !type !34029 !type !34030
... fn merging
; Function Attrs: minsize nounwind optsize ssp uwtable(sync)
define internal void @foo(ptr nocapture noundef readonly %0) #0 !type !type !34028 !type !34029 !type !34030
```

This patch makes sure that the entire vector of metadata is copied over.

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/IPO/MergeFunctions.cpp b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
index 05a3b16..b50a700 100644
--- a/llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -712,11 +712,13 @@ static bool canCreateThunkFor(Function *F) {
   return true;
 }
 
-/// Copy metadata from one function to another.
-static void copyMetadataIfPresent(Function *From, Function *To, StringRef Key) {
-  if (MDNode *MD = From->getMetadata(Key)) {
-    To->setMetadata(Key, MD);
-  }
+/// Copy all metadata of a specific kind from one function to another.
+static void copyMetadataIfPresent(Function *From, Function *To,
+                                  StringRef Kind) {
+  SmallVector<MDNode *, 4> MDs;
+  From->getMetadata(Kind, MDs);
+  for (MDNode *MD : MDs)
+    To->addMetadata(Kind, *MD);
 }
 
 // Replace G with a simple tail call to bitcast(F). Also (unless