1 files changed, 44 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp b/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
index 0642d51..6d4436b 100644
--- a/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
+++ b/llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp
@@ -16,22 +16,62 @@
 
 using namespace llvm;
 
+static void mergeAttributes(LLVMContext &Ctx, const Module &M,
+                            const DataLayout &DL, const Triple &TT,
+                            Function *Func, FunctionType *FuncTy,
+                            AttributeList FuncAttrs) {
+  AttributeList OldAttrs = Func->getAttributes();
+  AttributeList NewAttrs = OldAttrs;
+
+  {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getFnAttrs());
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getFnAttrs());
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addFnAttributes(Ctx, OldBuilder);
+  }
+
+  {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getRetAttrs());
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getRetAttrs());
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addRetAttributes(Ctx, OldBuilder);
+  }
+
+  for (unsigned I = 0, E = FuncTy->getNumParams(); I != E; ++I) {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getParamAttrs(I));
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getParamAttrs(I));
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addParamAttributes(Ctx, I, OldBuilder);
+  }
+
+  Func->setAttributes(NewAttrs);
+}
+
 PreservedAnalyses DeclareRuntimeLibcallsPass::run(Module &M,
                                                   ModuleAnalysisManager &MAM) {
   RTLIB::RuntimeLibcallsInfo RTLCI(M.getTargetTriple());
   LLVMContext &Ctx = M.getContext();
+  const DataLayout &DL = M.getDataLayout();
+  const Triple &TT = M.getTargetTriple();
 
   for (RTLIB::LibcallImpl Impl : RTLCI.getLibcallImpls()) {
     if (Impl == RTLIB::Unsupported)
       continue;
 
-    // TODO: Declare with correct type, calling convention, and attributes.
+    auto [FuncTy, FuncAttrs] = RTLCI.getFunctionTy(Ctx, TT, DL, Impl);
 
-    FunctionType *FuncTy =
-        FunctionType::get(Type::getVoidTy(Ctx), {}, /*IsVarArgs=*/true);
+    // TODO: Declare with correct type, calling convention, and attributes.
+    if (!FuncTy)
+      FuncTy = FunctionType::get(Type::getVoidTy(Ctx), {}, /*IsVarArgs=*/true);
 
     StringRef FuncName = RTLCI.getLibcallImplName(Impl);
-    M.getOrInsertFunction(FuncName, FuncTy);
+
+    Function *Func =
+        cast<Function>(M.getOrInsertFunction(FuncName, FuncTy).getCallee());
+    if (Func->getFunctionType() == FuncTy) {
+      mergeAttributes(Ctx, M, DL, TT, Func, FuncTy, FuncAttrs);
+      Func->setCallingConv(RTLCI.getLibcallImplCallingConv(Impl));
+    }
   }
 
   return PreservedAnalyses::none();