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

1 files changed, 64 insertions, 6 deletions

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()) {