[llvm] r312905 - [AVR] Enable the '__do_copy_data' function

[Dylan McKay via llvm-commits]

Author: dylanmckay
Date: Mon Sep 11 03:32:51 2017
New Revision: 312905

URL: http://llvm.org/viewvc/llvm-project?rev=312905&view=rev
Log:
[AVR] Enable the '__do_copy_data' function

Also enables '__do_clear_bss'.

These functions are automaticalled called by the CRT if they are
declared.

We need these to be called otherwise RAM will start completely
uninitialised, even though we need to copy RAM variables from progmem to
RAM.

Added:
    llvm/trunk/test/CodeGen/AVR/clear-bss.ll
    llvm/trunk/test/CodeGen/AVR/copy-data-to-ram.ll
Modified:
    llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp
    llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h

Modified: llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp?rev=312905&r1=312904&r2=312905&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp (original)
+++ llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.cpp Mon Sep 11 03:32:51 2017
@@ -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(MCS
 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
 

Modified: llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h?rev=312905&r1=312904&r2=312905&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h (original)
+++ llvm/trunk/lib/Target/AVR/MCTargetDesc/AVRTargetStreamer.h Mon Sep 11 03:32:51 2017
@@ -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.

Added: llvm/trunk/test/CodeGen/AVR/clear-bss.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AVR/clear-bss.ll?rev=312905&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AVR/clear-bss.ll (added)
+++ llvm/trunk/test/CodeGen/AVR/clear-bss.ll Mon Sep 11 03:32:51 2017
@@ -0,0 +1,5 @@
+; RUN: llc < %s -march=avr | FileCheck %s
+
+; CHECK: .globl __do_clear_bss
+ at zeroed = internal constant [3 x i8] zeroinitializer
+

Added: llvm/trunk/test/CodeGen/AVR/copy-data-to-ram.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AVR/copy-data-to-ram.ll?rev=312905&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/AVR/copy-data-to-ram.ll (added)
+++ llvm/trunk/test/CodeGen/AVR/copy-data-to-ram.ll Mon Sep 11 03:32:51 2017
@@ -0,0 +1,5 @@
+; RUN: llc < %s -march=avr | FileCheck %s
+
+; CHECK: .globl __do_copy_data
+ at str = internal global [3 x i8] c"foo"
+