[CodeGen] don't emit addrsig symbol if it's used only by metadata

Value only used by metadata can be removed from .addrsig table.
This solves the undefined symbol error when enabling addrsig table on COFF LTO.

Differential Revision: https://reviews.llvm.org/D101512

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/IR/Value.cpp b/llvm/lib/IR/Value.cpp
index 47a5be4..8d6918c 100644
--- a/llvm/lib/IR/Value.cpp
+++ b/llvm/lib/IR/Value.cpp
@@ -980,6 +980,27 @@ bool Value::isSwiftError() const {
   return Alloca->isSwiftError();
 }
 
+bool Value::isTransitiveUsedByMetadataOnly() const {
+  if (use_empty())
+    return false;
+  llvm::SmallVector<const User *, 32> WorkList;
+  llvm::SmallPtrSet<const User *, 32> Visited;
+  WorkList.insert(WorkList.begin(), user_begin(), user_end());
+  while (!WorkList.empty()) {
+    const User *U = WorkList.back();
+    WorkList.pop_back();
+    Visited.insert(U);
+    // If it is transitively used by a global value or a non-constant value,
+    // it's obviously not only used by metadata.
+    if (!isa<Constant>(U) || isa<GlobalValue>(U))
+      return false;
+    for (const User *UU : U->users())
+      if (!Visited.count(UU))
+        WorkList.push_back(UU);
+  }
+  return true;
+}
+
 //===----------------------------------------------------------------------===//
 //                             ValueHandleBase Class
 //===----------------------------------------------------------------------===//