Utility functions for appending to llvm.used/llvm.compiler.used.

llvm-svn: 285143

1 files changed, 38 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/ModuleUtils.cpp b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
index eb918851862..4f8737e9b93 100644
--- a/llvm/lib/Transforms/Utils/ModuleUtils.cpp
+++ b/llvm/lib/Transforms/Utils/ModuleUtils.cpp
@@ -89,6 +89,44 @@ void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *D
   appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
 }
 
+static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
+  GlobalVariable *GV = M.getGlobalVariable(Name);
+  SmallPtrSet<Constant *, 16> InitAsSet;
+  SmallVector<Constant *, 16> Init;
+  if (GV) {
+    ConstantArray *CA = dyn_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();
+  }
+
+  Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
+  for (auto *V : Values) {
+    Constant *C = ConstantExpr::getBitCast(V, Int8PtrTy);
+    if (InitAsSet.insert(C).second)
+      Init.push_back(C);
+  }
+
+  if (Init.empty())
+    return;
+
+  ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
+  GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
+                                ConstantArray::get(ATy, Init), Name);
+  GV->setSection("llvm.metadata");
+}
+
+void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
+  appendToUsedList(M, "llvm.used", Values);
+}
+
+void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
+  appendToUsedList(M, "llvm.compiler.used", Values);
+}
+
 Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
   if (isa<Function>(FuncOrBitcast))
     return cast<Function>(FuncOrBitcast);