From 235b830328586f0eb141f3263a0868166d80f478 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Thu, 28 Apr 2011 04:04:14 +0000
Subject: [PATCH] Add a small temporary hack for producing identical eh_frame
 sections on OS X. This removes one of the main advantages of moving eh_frame
 to MC, but makes the transition a lot easier to debug (run md5).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130379 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/MC/MCDwarf.h |  4 +++-
 lib/MC/MCAssembler.cpp    |  3 ++-
 lib/MC/MCDwarf.cpp        | 17 ++++++++++++-----
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/include/llvm/MC/MCDwarf.h b/include/llvm/MC/MCDwarf.h
index a8f84c5a752..220d63087b8 100644
--- a/include/llvm/MC/MCDwarf.h
+++ b/include/llvm/MC/MCDwarf.h
@@ -23,6 +23,7 @@
 #include <vector>
 
 namespace llvm {
+  class TargetAsmInfo;
   class MachineMove;
   class MCContext;
   class MCExpr;
@@ -282,7 +283,8 @@ namespace llvm {
     //
     static void Emit(MCStreamer &streamer);
     static void EmitAdvanceLoc(MCStreamer &Streamer, uint64_t AddrDelta);
-    static void EncodeAdvanceLoc(uint64_t AddrDelta, raw_ostream &OS);
+    static void EncodeAdvanceLoc(uint64_t AddrDelta, raw_ostream &OS,
+                                 const TargetAsmInfo &AsmInfo);
   };
 } // end namespace llvm
 
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index 3c9487bffec..3ebe69c5bd5 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -732,7 +732,8 @@ bool MCAssembler::RelaxDwarfCallFrameFragment(MCAsmLayout &Layout,
   SmallString<8> &Data = DF.getContents();
   Data.clear();
   raw_svector_ostream OSE(Data);
-  MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OSE);
+  const TargetAsmInfo &AsmInfo = getContext().getTargetAsmInfo();
+  MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OSE, AsmInfo);
   OSE.flush();
   return OldSize != Data.size();
 }
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index a40e3853c03..51d0ed83332 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -843,21 +843,28 @@ void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
                                          uint64_t AddrDelta) {
   SmallString<256> Tmp;
   raw_svector_ostream OS(Tmp);
-  MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS);
+  const TargetAsmInfo &AsmInfo = Streamer.getContext().getTargetAsmInfo();
+  MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS, AsmInfo);
   Streamer.EmitBytes(OS.str(), /*AddrSpace=*/0);
 }
 
 void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
-                                           raw_ostream &OS) {
+                                           raw_ostream &OS,
+                                           const TargetAsmInfo &AsmInfo) {
+  // This is a small hack to facilitate the transition to CFI on OS X. It
+  // relaxes all address advances which lets us produces identical output
+  // to the one produce by CodeGen.
+  const bool Relax = !AsmInfo.isFunctionEHFrameSymbolPrivate();
+
   // FIXME: Assumes the code alignment factor is 1.
   if (AddrDelta == 0) {
-  } else if (isUIntN(6, AddrDelta)) {
+  } else if (isUIntN(6, AddrDelta) && !Relax) {
     uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
     OS << Opcode;
-  } else if (isUInt<8>(AddrDelta)) {
+  } else if (isUInt<8>(AddrDelta) && !Relax) {
     OS << uint8_t(dwarf::DW_CFA_advance_loc1);
     OS << uint8_t(AddrDelta);
-  } else if (isUInt<16>(AddrDelta)) {
+  } else if (isUInt<16>(AddrDelta) && !Relax) {
     // FIXME: check what is the correct behavior on a big endian machine.
     OS << uint8_t(dwarf::DW_CFA_advance_loc2);
     OS << uint8_t( AddrDelta       & 0xff);
-- 
2.34.1