CodeGen: Mark the runtime function __dynamic_cast as readonly & nounwind.
This allows the optimizer to CSE dynamic_casts.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174289 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprCXX.cpp b/lib/CodeGen/CGExprCXX.cpp
index 8b7f234..853e25e 100644
--- a/lib/CodeGen/CGExprCXX.cpp
+++ b/lib/CodeGen/CGExprCXX.cpp
@@ -1689,11 +1689,16 @@
CGF.ConvertType(CGF.getContext().getPointerDiffType());
llvm::Type *Args[4] = { Int8PtrTy, Int8PtrTy, Int8PtrTy, PtrDiffTy };
-
- llvm::FunctionType *FTy =
- llvm::FunctionType::get(Int8PtrTy, Args, false);
-
- return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast");
+
+ llvm::FunctionType *FTy = llvm::FunctionType::get(Int8PtrTy, Args, false);
+
+ // Mark the function as nounwind readonly.
+ llvm::Attribute::AttrKind FuncAttrs[] = { llvm::Attribute::NoUnwind,
+ llvm::Attribute::ReadOnly };
+ llvm::AttributeSet Attrs = llvm::AttributeSet::get(
+ CGF.getLLVMContext(), llvm::AttributeSet::FunctionIndex, FuncAttrs);
+
+ return CGF.CGM.CreateRuntimeFunction(FTy, "__dynamic_cast", Attrs);
}
static llvm::Constant *getBadCastFn(CodeGenFunction &CGF) {