Debug Info: use module flag to set up Dwarf version.

Correctly handles ref_addr depending on the Dwarf version. Emit Dwarf with
version from module flag.

TODO: turn on/off features depending on the Dwarf version.
llvm-svn: 185484

4 files changed, 44 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index 4b6698e374e..d6caef7e5b8 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "DIE.h"
+#include "DwarfDebug.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/IR/DataLayout.h"
@@ -331,6 +332,16 @@ void DIEEntry::EmitValue(AsmPrinter *AP, unsigned Form) const {
   AP->EmitInt32(Entry->getOffset());
 }
 
+unsigned DIEEntry::getRefAddrSize(AsmPrinter *AP) {
+  // DWARF4: References that use the attribute form DW_FORM_ref_addr are
+  // specified to be four bytes in the DWARF 32-bit format and eight bytes
+  // in the DWARF 64-bit format, while DWARF Version 2 specifies that such
+  // references have the same size as an address on the target system.
+  if (AP->getDwarfDebug()->getDwarfVersion() == 2)
+    return AP->getDataLayout().getPointerSize();
+  return sizeof(int32_t);
+}
+
 #ifndef NDEBUG
 void DIEEntry::print(raw_ostream &O) const {
   O << format("Die: 0x%lx", (long)(intptr_t)Entry);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.h b/llvm/lib/CodeGen/AsmPrinter/DIE.h
index 412c09c6c8e..3b04e206254 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.h
@@ -365,9 +365,13 @@ namespace llvm {
     /// SizeOf - Determine size of debug information entry in bytes.
     ///
     virtual unsigned SizeOf(AsmPrinter *AP, unsigned Form) const {
-      return sizeof(int32_t);
+      return Form == dwarf::DW_FORM_ref_addr ? getRefAddrSize(AP) :
+                                               sizeof(int32_t);
     }
 
+    /// Returns size of a ref_addr entry.
+    static unsigned getRefAddrSize(AsmPrinter *AP);
+
     // Implement isa/cast/dyncast.
     static bool classof(const DIEValue *E) { return E->getType() == isEntry; }
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 7e6336efeca..cc5997d018f 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -162,6 +162,21 @@ DIType DbgVariable::getType() const {
 
 } // end llvm namespace
 
+/// Return Dwarf Version by checking module flags.
+static unsigned getDwarfVersionFromModule(const Module *M) {
+  SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
+  M->getModuleFlagsMetadata(ModuleFlags);
+  for (unsigned I = 0, E = ModuleFlags.size(); I < E; ++I) {
+    const Module::ModuleFlagEntry &MFE = ModuleFlags[I];
+    StringRef Key = MFE.Key->getString();
+    Value *Val = MFE.Val;
+
+    if (Key == "Dwarf Version")
+      return cast<ConstantInt>(Val)->getZExtValue();
+  }
+  return dwarf::DWARF_VERSION;
+}
+
 DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   : Asm(A), MMI(Asm->MMI), FirstCU(0),
     AbbreviationsSet(InitAbbreviationsSetSize),
@@ -204,6 +219,8 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   else
     HasSplitDwarf = SplitDwarf == Enable ? true : false;
 
+  DwarfVersion = getDwarfVersionFromModule(MMI->getModule());
+
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
     beginModule();
@@ -1900,7 +1917,8 @@ void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
         DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
         Addr += Holder.getCUOffset(Origin->getCompileUnit());
       }
-      Asm->EmitInt32(Addr);
+      Asm->OutStreamer.EmitIntValue(Addr,
+          Form == dwarf::DW_FORM_ref_addr ? DIEEntry::getRefAddrSize(Asm) : 4);
       break;
     }
     case dwarf::DW_AT_ranges: {
@@ -1984,7 +2002,7 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
     Asm->OutStreamer.AddComment("Length of Compilation Unit Info");
     Asm->EmitInt32(ContentSize);
     Asm->OutStreamer.AddComment("DWARF version number");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
+    Asm->EmitInt16(DD->getDwarfVersion());
     Asm->OutStreamer.AddComment("Offset Into Abbrev. Section");
     Asm->EmitSectionOffset(Asm->GetTempSymbol(ASection->getLabelBeginName()),
                            ASectionSym);
@@ -2225,7 +2243,7 @@ void DwarfDebug::emitDebugPubnames() {
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("pubnames_begin", ID));
 
     Asm->OutStreamer.AddComment("DWARF Version");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
+    Asm->EmitInt16(DwarfVersion);
 
     Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
     Asm->EmitSectionOffset(Asm->GetTempSymbol(ISec->getLabelBeginName(), ID),
@@ -2272,7 +2290,7 @@ void DwarfDebug::emitDebugPubTypes() {
                                                   TheCU->getUniqueID()));
 
     if (Asm->isVerbose()) Asm->OutStreamer.AddComment("DWARF Version");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
+    Asm->EmitInt16(DwarfVersion);
 
     Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
     const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
@@ -2553,7 +2571,7 @@ void DwarfDebug::emitDebugInlineInfo() {
   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_inlined_begin", 1));
 
   Asm->OutStreamer.AddComment("Dwarf Version");
-  Asm->EmitInt16(dwarf::DWARF_VERSION);
+  Asm->EmitInt16(DwarfVersion);
   Asm->OutStreamer.AddComment("Address Size (in bytes)");
   Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 60c6c3fa4c2..1a036885b2e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -407,6 +407,8 @@ class DwarfDebug {
   bool HasDwarfAccelTables;
   bool HasSplitDwarf;
 
+  unsigned DwarfVersion;
+
   // Separated Dwarf Variables
   // In general these will all be for bits that are left in the
   // original object file, rather than things that are meant
@@ -650,6 +652,9 @@ public:
   /// \brief Returns whether or not to change the current debug info for the
   /// split dwarf proposal support.
   bool useSplitDwarf() { return HasSplitDwarf; }
+
+  /// Returns the Dwarf Version.
+  unsigned getDwarfVersion() const { return DwarfVersion; }
 };
 } // End of namespace llvm