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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166677 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 21 insertions, 5 deletions

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index b8b3188ce4..eda062376e 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/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/lib/MC/MCELFObjectTargetWriter.cpp b/lib/MC/MCELFObjectTargetWriter.cpp
index 6eb6914f4b..74cd042a0f 100644
--- a/lib/MC/MCELFObjectTargetWriter.cpp
+++ b/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) {