[LTO] Fix cloning of llvm*.used when splitting module

Refines the fix in 3c4c205060c9398da705eb71b63ddd8a04999de9 to only
put globals whose defs were cloned into the split regular LTO module
on the cloned llvm*.used globals. This avoids an issue where one of the
attached values was a local that was promoted in the original module
after the module was cloned. We only need to have the values defined in
the new module on those globals.

Fixes PR49251.

Differential Revision: https://reviews.llvm.org/D97013

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index ef9f18a..f7bd8f0 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -76,11 +76,13 @@ static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *>
   SmallPtrSet<Constant *, 16> InitAsSet;
   SmallVector<Constant *, 16> Init;
   if (GV) {
-    auto *CA = cast<ConstantArray>(GV->getInitializer());
-    for (auto &Op : CA->operands()) {
-      Constant *C = cast_or_null<Constant>(Op);
-      if (InitAsSet.insert(C).second)
-        Init.push_back(C);
+    if (GV->hasInitializer()) {
+      auto *CA = cast<ConstantArray>(GV->getInitializer());
+      for (auto &Op : CA->operands()) {
+        Constant *C = cast_or_null<Constant>(Op);
+        if (InitAsSet.insert(C).second)
+          Init.push_back(C);
+      }
     }
     GV->eraseFromParent();
   }