Initial TOC support for PowerPC64 object creation

This patch adds initial PPC64 TOC MC object creation using the small mcmodel
(a single 64K TOC) adding the some TOC relocations (R_PPC64_TOC,
R_PPC64_TOC16, and R_PPC64_TOC16DS).

The addition of 'undefinedExplicitRelSym' hook on 'MCELFObjectTargetWriter'
is meant to avoid the creation of an unreferenced ".TOC." symbol (used in
the .odp creation) as well to set the R_PPC64_TOC relocation target as the
temporary ".TOC." symbol. On PPC64 ABI, the R_PPC64_TOC relocation should
not point to any symbol.

llvm-svn: 166677

8 files changed, 149 insertions, 23 deletions

diff --git a/llvm/lib/MC/ELFObjectWriter.cpp b/llvm/lib/MC/ELFObjectWriter.cpp
index b8b3188ce48..eda062376ed 100644
--- a/llvm/lib/MC/ELFObjectWriter.cpp
+++ b/llvm/lib/MC/ELFObjectWriter.cpp
@@ -133,6 +133,11 @@ class ELFObjectWriter : public MCObjectWriter {
                                    bool IsPCRel) const {
       return TargetObjectWriter->ExplicitRelSym(Asm, Target, F, Fixup, IsPCRel);
     }
+    const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
+                                            const MCFixup &Fixup,
+                                            bool IsPCRel) const {
+      return TargetObjectWriter->undefinedExplicitRelSym(Target, Fixup, IsPCRel);
+    }
 
     bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
     bool hasRelocationAddend() const {
@@ -639,7 +644,7 @@ const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
   if (ASymbol.isUndefined()) {
     if (Renamed)
       return Renamed;
-    return &ASymbol;
+    return undefinedExplicitRelSym(Target, Fixup, IsPCRel);
   }
 
   if (SD.isExternal()) {
@@ -721,10 +726,13 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
       MCSymbolData &SD = Asm.getSymbolData(ASymbol);
       MCFragment *F = SD.getFragment();
 
-      Index = F->getParent()->getOrdinal() + 1;
-
-      // Offset of the symbol in the section
-      Value += Layout.getSymbolOffset(&SD);
+      if (F) {
+        Index = F->getParent()->getOrdinal() + 1;
+        // Offset of the symbol in the section
+        Value += Layout.getSymbolOffset(&SD);
+      } else {
+        Index = 0;
+      }
     } else {
       if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
         WeakrefUsedInReloc.insert(RelocSymbol);
diff --git a/llvm/lib/MC/MCELFObjectTargetWriter.cpp b/llvm/lib/MC/MCELFObjectTargetWriter.cpp
index 6eb6914f4b1..74cd042a0f8 100644
--- a/llvm/lib/MC/MCELFObjectTargetWriter.cpp
+++ b/llvm/lib/MC/MCELFObjectTargetWriter.cpp
@@ -9,6 +9,8 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/MC/MCELFObjectWriter.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
 
 using namespace llvm;
 
@@ -35,6 +37,12 @@ const MCSymbol *MCELFObjectTargetWriter::ExplicitRelSym(const MCAssembler &Asm,
   return NULL;
 }
 
+const MCSymbol *MCELFObjectTargetWriter::undefinedExplicitRelSym(const MCValue &Target,
+                                                                 const MCFixup &Fixup,
+                                                                 bool IsPCRel) const {
+  const MCSymbol &Symbol = Target.getSymA()->getSymbol();
+  return &Symbol.AliasedSymbol();
+}
 
 void MCELFObjectTargetWriter::adjustFixupOffset(const MCFixup &Fixup,
                                                 uint64_t &RelocOffset) {
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
index 17447386222..87ecb13a4c7 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
@@ -29,9 +29,14 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
   case FK_Data_1:
   case FK_Data_2:
   case FK_Data_4:
+  case FK_Data_8:
+  case PPC::fixup_ppc_toc:
     return Value;
+  case PPC::fixup_ppc_lo14:
+  case PPC::fixup_ppc_toc16_ds:
+    return (Value & 0xffff) << 2;
   case PPC::fixup_ppc_brcond14:
-    return Value & 0x3ffc;
+    return Value & 0xfffc;
   case PPC::fixup_ppc_br24:
     return Value & 0x3fffffc;
 #if 0
@@ -41,6 +46,7 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
   case PPC::fixup_ppc_ha16:
     return ((Value >> 16) + ((Value & 0x8000) ? 1 : 0)) & 0xffff;
   case PPC::fixup_ppc_lo16:
+  case PPC::fixup_ppc_toc16:
     return Value & 0xffff;
   }
 }
@@ -72,7 +78,10 @@ public:
       { "fixup_ppc_brcond14",    16,     14,   MCFixupKindInfo::FKF_IsPCRel },
       { "fixup_ppc_lo16",        16,     16,   0 },
       { "fixup_ppc_ha16",        16,     16,   0 },
-      { "fixup_ppc_lo14",        16,     14,   0 }
+      { "fixup_ppc_lo14",        16,     14,   0 },
+      { "fixup_ppc_toc",          0,     64,   0 },
+      { "fixup_ppc_toc16",       16,     16,   0 },
+      { "fixup_ppc_toc16_ds",    16,     14,   0 }
     };
 
     if (Kind < FirstTargetFixupKind)
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
index a19798157bf..de3c3523a9a 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
@@ -11,6 +11,8 @@
 #include "MCTargetDesc/PPCMCTargetDesc.h"
 #include "llvm/MC/MCELFObjectWriter.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
 
 using namespace llvm;
 
@@ -21,9 +23,15 @@ namespace {
 
     virtual ~PPCELFObjectWriter();
   protected:
+    virtual unsigned getRelocTypeInner(const MCValue &Target,
+                                       const MCFixup &Fixup,
+                                       bool IsPCRel) const;
     virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
                                   bool IsPCRel, bool IsRelocWithSymbol,
                                   int64_t Addend) const;
+    virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
+                                                    const MCFixup &Fixup,
+                                                    bool IsPCRel) const;
     virtual void adjustFixupOffset(const MCFixup &Fixup, uint64_t &RelocOffset);
   };
 }
@@ -36,11 +44,13 @@ PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
 PPCELFObjectWriter::~PPCELFObjectWriter() {
 }
 
-unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
-                                             const MCFixup &Fixup,
-                                             bool IsPCRel,
-                                             bool IsRelocWithSymbol,
-                                             int64_t Addend) const {
+unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
+                                               const MCFixup &Fixup,
+                                               bool IsPCRel) const
+{
+  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
+    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
+
   // determine the type of the relocation
   unsigned Type;
   if (IsPCRel) {
@@ -61,7 +71,7 @@ unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
       Type = ELF::R_PPC_ADDR24;
       break;
     case PPC::fixup_ppc_brcond14:
-      Type = ELF::R_PPC_ADDR14_BRTAKEN; // XXX: or BRNTAKEN?_
+      Type = ELF::R_PPC_ADDR14; // XXX: or BRNTAKEN?_
       break;
     case PPC::fixup_ppc_ha16:
       Type = ELF::R_PPC_ADDR16_HA;
@@ -72,6 +82,26 @@ unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
     case PPC::fixup_ppc_lo14:
       Type = ELF::R_PPC_ADDR14;
       break;
+    case PPC::fixup_ppc_toc:
+      Type = ELF::R_PPC64_TOC;
+      break;
+    case PPC::fixup_ppc_toc16:
+      Type = ELF::R_PPC64_TOC16;
+      break;
+    case PPC::fixup_ppc_toc16_ds:
+      Type = ELF::R_PPC64_TOC16_DS;
+      break;
+    case FK_Data_8:
+      switch (Modifier) {
+      default: llvm_unreachable("Unsupported Modifier");
+      case MCSymbolRefExpr::VK_PPC_TOC:
+        Type = ELF::R_PPC64_TOC;
+        break;
+      case MCSymbolRefExpr::VK_None:
+        Type = ELF::R_PPC64_ADDR64;
+	break;
+      }
+      break;
     case FK_Data_4:
       Type = ELF::R_PPC_ADDR32;
       break;
@@ -83,6 +113,34 @@ unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
   return Type;
 }
 
+unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
+                                          const MCFixup &Fixup,
+                                          bool IsPCRel,
+                                          bool IsRelocWithSymbol,
+                                          int64_t Addend) const {
+  return getRelocTypeInner(Target, Fixup, IsPCRel);
+}
+
+const MCSymbol *PPCELFObjectWriter::undefinedExplicitRelSym(const MCValue &Target,
+                                                            const MCFixup &Fixup,
+                                                            bool IsPCRel) const {
+  assert(Target.getSymA() && "SymA cannot be 0");
+  const MCSymbol &Symbol = Target.getSymA()->getSymbol().AliasedSymbol();
+
+  unsigned RelocType = getRelocTypeInner(Target, Fixup, IsPCRel);
+
+  // The .odp creation emits a relocation against the symbol ".TOC." which
+  // create a R_PPC64_TOC relocation. However the relocation symbol name
+  // in final object creation should be NULL, since the symbol does not
+  // really exist, it is just the reference to TOC base for the current
+  // object file.
+  bool EmitThisSym = RelocType != ELF::R_PPC64_TOC;
+
+  if (EmitThisSym && !Symbol.isTemporary())
+    return &Symbol;
+  return NULL;
+}
+
 void PPCELFObjectWriter::
 adjustFixupOffset(const MCFixup &Fixup, uint64_t &RelocOffset) {
   switch ((unsigned)Fixup.getKind()) {
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCFixupKinds.h b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCFixupKinds.h
index b3c889e3f8d..37b265e7fd3 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCFixupKinds.h
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCFixupKinds.h
@@ -34,6 +34,16 @@ enum Fixups {
   /// fixup_ppc_lo14 - A 14-bit fixup corresponding to lo16(_foo) for instrs
   /// like 'std'.
   fixup_ppc_lo14,
+
+  /// fixup_ppc_toc - Insert value of TOC base (.TOC.).
+  fixup_ppc_toc,
+
+  /// fixup_ppc_toc16 - A 16-bit signed fixup relative to the TOC base.
+  fixup_ppc_toc16,
+
+  /// fixup_ppc_toc16_ds - A 14-bit signed fixup relative to the TOC base with
+  /// implied 2 zero bits
+  fixup_ppc_toc16_ds,
   
   // Marker
   LastTargetFixupKind,
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
index 1fba5b8dc35..635d6c80f09 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
@@ -15,7 +15,9 @@
 #include "MCTargetDesc/PPCBaseInfo.h"
 #include "MCTargetDesc/PPCFixupKinds.h"
 #include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstrInfo.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -28,13 +30,25 @@ class PPCMCCodeEmitter : public MCCodeEmitter {
   PPCMCCodeEmitter(const PPCMCCodeEmitter &) LLVM_DELETED_FUNCTION;
   void operator=(const PPCMCCodeEmitter &) LLVM_DELETED_FUNCTION;
 
+  const MCSubtargetInfo &STI;
+  Triple TT;
+
 public:
   PPCMCCodeEmitter(const MCInstrInfo &mcii, const MCSubtargetInfo &sti,
-                   MCContext &ctx) {
+                   MCContext &ctx)
+    : STI(sti), TT(STI.getTargetTriple()) {
   }
   
   ~PPCMCCodeEmitter() {}
 
+  bool is64BitMode() const {
+    return (STI.getFeatureBits() & PPC::Feature64Bit) != 0;
+  }
+
+  bool isSVR4ABI() const {
+    return TT.isMacOSX() == 0;
+  }
+
   unsigned getDirectBrEncoding(const MCInst &MI, unsigned OpNo,
                                SmallVectorImpl<MCFixup> &Fixups) const;
   unsigned getCondBrEncoding(const MCInst &MI, unsigned OpNo,
@@ -140,8 +154,12 @@ unsigned PPCMCCodeEmitter::getMemRIEncoding(const MCInst &MI, unsigned OpNo,
     return (getMachineOpValue(MI, MO, Fixups) & 0xFFFF) | RegBits;
   
   // Add a fixup for the displacement field.
-  Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
-                                   (MCFixupKind)PPC::fixup_ppc_lo16));
+  if (isSVR4ABI() && is64BitMode())
+    Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
+                                     (MCFixupKind)PPC::fixup_ppc_toc16));
+  else
+    Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
+                                     (MCFixupKind)PPC::fixup_ppc_lo16));
   return RegBits;
 }
 
@@ -158,8 +176,12 @@ unsigned PPCMCCodeEmitter::getMemRIXEncoding(const MCInst &MI, unsigned OpNo,
     return (getMachineOpValue(MI, MO, Fixups) & 0x3FFF) | RegBits;
   
   // Add a fixup for the branch target.
-  Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
-                                   (MCFixupKind)PPC::fixup_ppc_lo14));
+  if (isSVR4ABI() && is64BitMode())
+    Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
+                                     (MCFixupKind)PPC::fixup_ppc_toc16_ds));
+  else
+    Fixups.push_back(MCFixup::Create(0, MO.getExpr(),
+                                     (MCFixupKind)PPC::fixup_ppc_lo14));
   return RegBits;
 }
 
diff --git a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
index d8abd9fba07..6941413ed46 100644
--- a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -420,10 +420,14 @@ void PPCLinuxAsmPrinter::EmitFunctionEntryLabel() {
   OutStreamer.EmitValueToAlignment(8);
   MCSymbol *Symbol1 = 
     OutContext.GetOrCreateSymbol(".L." + Twine(CurrentFnSym->getName()));
-  MCSymbol *Symbol2 = OutContext.GetOrCreateSymbol(StringRef(".TOC.@tocbase"));
+  // Generates a R_PPC64_ADDR64 (from FK_DATA_8) relocation for the function
+  // entry point.
   OutStreamer.EmitValue(MCSymbolRefExpr::Create(Symbol1, OutContext),
                         8/*size*/, 0/*addrspace*/);
-  OutStreamer.EmitValue(MCSymbolRefExpr::Create(Symbol2, OutContext),
+  MCSymbol *Symbol2 = OutContext.GetOrCreateSymbol(StringRef(".TOC."));
+  // Generates a R_PPC64_TOC relocation for TOC base insertion.
+  OutStreamer.EmitValue(MCSymbolRefExpr::Create(Symbol2,
+                        MCSymbolRefExpr::VK_PPC_TOC, OutContext),
                         8/*size*/, 0/*addrspace*/);
   // Emit a null environment pointer.
   OutStreamer.EmitIntValue(0, 8 /* size */, 0 /* addrspace */);
diff --git a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
index 14b8534d1cb..9c8cb92cc7e 100644
--- a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
+++ b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
@@ -54,19 +54,26 @@ PPCSubtarget::PPCSubtarget(const std::string &TT, const std::string &CPU,
     CPUName = sys::getHostCPUName();
 #endif
 
-  // Parse features string.
-  ParseSubtargetFeatures(CPUName, FS);
-
   // Initialize scheduling itinerary for the specified CPU.
   InstrItins = getInstrItineraryForCPU(CPUName);
 
+  // Make sure 64-bit features are available when CPUname is generic
+  std::string FullFS = FS;
+
   // If we are generating code for ppc64, verify that options make sense.
   if (is64Bit) {
     Has64BitSupport = true;
     // Silently force 64-bit register use on ppc64.
     Use64BitRegs = true;
+    if (!FullFS.empty())
+      FullFS = "+64bit," + FullFS;
+    else
+      FullFS = "+64bit";
   }
 
+  // Parse features string.
+  ParseSubtargetFeatures(CPUName, FullFS);
+
   // If the user requested use of 64-bit regs, but the cpu selected doesn't
   // support it, ignore.
   if (use64BitRegs() && !has64BitSupport())