2 files changed, 22 insertions, 0 deletions
diff --git a/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp b/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp
index a2d8c16eeb8..2b45d9adc7e 100644
--- a/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp
+++ b/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp
@@ -13,6 +13,8 @@
 
 #include "AVRTargetStreamer.h"
 
+#include "llvm/MC/MCContext.h"
+
 namespace llvm {
 
 AVRTargetStreamer::AVRTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
@@ -20,5 +22,23 @@ AVRTargetStreamer::AVRTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
 AVRTargetAsmStreamer::AVRTargetAsmStreamer(MCStreamer &S)
     : AVRTargetStreamer(S) {}
 
+void AVRTargetStreamer::finish() {
+  MCStreamer &OS = getStreamer();
+  MCContext &Context = OS.getContext();
+
+  MCSymbol *DoCopyData = Context.getOrCreateSymbol("__do_copy_data");
+  MCSymbol *DoClearBss = Context.getOrCreateSymbol("__do_clear_bss");
+
+  // FIXME: We can disable __do_copy_data if there are no static RAM variables.
+
+  OS.emitRawComment(" Declaring this symbol tells the CRT that it should");
+  OS.emitRawComment("copy all variables from program memory to RAM on startup");
+  OS.EmitSymbolAttribute(DoCopyData, MCSA_Global);
+
+  OS.emitRawComment(" Declaring this symbol tells the CRT that it should");
+  OS.emitRawComment("clear the zeroed data section on startup");
+  OS.EmitSymbolAttribute(DoClearBss, MCSA_Global);
+}
+
 } // end namespace llvm
 
diff --git a/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h b/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h
index 99a536699ae..815088b0a5d 100644
--- a/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h
+++ b/llvm/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h
@@ -19,6 +19,8 @@ class MCStreamer;
 class AVRTargetStreamer : public MCTargetStreamer {
 public:
   explicit AVRTargetStreamer(MCStreamer &S);
+
+  void finish() override;
 };
 
 /// A target streamer for textual AVR assembly code.