Subzero: Emit ARM build-attributes in the file scope (as header).

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index 49c370ab151feda68d8bdafeab3e9a3d1dd31edc..8ba5778eb79139880c9eb186e167bab815bdd302 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -444,4 +444,18 @@ TargetDataLowering::createLowering(GlobalContext *Ctx) {
 
 TargetDataLowering::~TargetDataLowering() {}
 
+std::unique_ptr<TargetHeaderLowering>
+TargetHeaderLowering::createLowering(GlobalContext *Ctx) {
+  TargetArch Target = Ctx->getFlags().getTargetArch();
+#define SUBZERO_TARGET(X)                                                      \
+  if (Target == Target_##X)                                                    \
+    return std::unique_ptr<TargetHeaderLowering>(TargetHeader##X::create(Ctx));
+#include "llvm/Config/SZTargets.def"
+
+  llvm_unreachable("Unsupported target header lowering");
+  return nullptr;
+}
+
+TargetHeaderLowering::~TargetHeaderLowering() {}
+
 } // end of namespace Ice