1 files changed, 6 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CGCUDABuiltin.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CGCUDABuiltin.cpp
index ea3b888635c3..44dd003757ad 100644
--- a/contrib/llvm/tools/clang/lib/CodeGen/CGCUDABuiltin.cpp
+++ b/contrib/llvm/tools/clang/lib/CodeGen/CGCUDABuiltin.cpp
@@ -99,6 +99,12 @@ CodeGenFunction::EmitCUDADevicePrintfCallExpr(const CallExpr *E,
     llvm::SmallVector<llvm::Type *, 8> ArgTypes;
     for (unsigned I = 1, NumArgs = Args.size(); I < NumArgs; ++I)
       ArgTypes.push_back(Args[I].RV.getScalarVal()->getType());
+
+    // Using llvm::StructType is correct only because printf doesn't accept
+    // aggregates.  If we had to handle aggregates here, we'd have to manually
+    // compute the offsets within the alloca -- we wouldn't be able to assume
+    // that the alignment of the llvm type was the same as the alignment of the
+    // clang type.
     llvm::Type *AllocaTy = llvm::StructType::create(ArgTypes, "printf_args");
     llvm::Value *Alloca = CreateTempAlloca(AllocaTy);