[PowerPC] Fix @got references to local symbols

A @got reference must always result in a relocation, so that
the linker has a chance to set up the GOT entry, even if the
symbol happens to be local.

Add a PPCELFObjectWriter::ExplicitRelSym routine that enforces
a relocation to be emitted for GOT references.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185353 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp b/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
index c2bf251..c26b545 100644
--- a/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
+++ b/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
@@ -30,6 +30,11 @@ namespace {
     virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
                                   bool IsPCRel, bool IsRelocWithSymbol,
                                   int64_t Addend) const;
+    virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
+                                           const MCValue &Target,
+                                           const MCFragment &F,
+                                           const MCFixup &Fixup,
+                                           bool IsPCRel) const;
     virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
                                                     const MCFixup &Fixup,
                                                     bool IsPCRel) const;
@@ -328,6 +333,35 @@ unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
   return getRelocTypeInner(Target, Fixup, IsPCRel);
 }
 
+const MCSymbol *PPCELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
+                                                   const MCValue &Target,
+                                                   const MCFragment &F,
+                                                   const MCFixup &Fixup,
+                                                   bool IsPCRel) const {
+  assert(Target.getSymA() && "SymA cannot be 0");
+  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
+    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
+
+  bool EmitThisSym;
+  switch (Modifier) {
+  // GOT references always need a relocation, even if the
+  // target symbol is local.
+  case MCSymbolRefExpr::VK_GOT:
+  case MCSymbolRefExpr::VK_PPC_GOT_LO:
+  case MCSymbolRefExpr::VK_PPC_GOT_HI:
+  case MCSymbolRefExpr::VK_PPC_GOT_HA:
+    EmitThisSym = true;
+    break;
+  default:
+    EmitThisSym = false;
+    break;
+  } 
+
+  if (EmitThisSym)
+    return &Target.getSymA()->getSymbol().AliasedSymbol();
+  return NULL;
+}
+
 const MCSymbol *PPCELFObjectWriter::undefinedExplicitRelSym(const MCValue &Target,
                                                             const MCFixup &Fixup,
                                                             bool IsPCRel) const {