Make it possible for the MCObjectWriter to decide if a given fixup is fully

resolved or not. Different object files have different restrictions and
different native assemblers have different idiosyncrasies we want to emulate
for now.

Move the existing MachO logic to the new place and implement an ELF one that
gets fixups to globals right.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115131 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 51 insertions, 4 deletions

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index b60271f1b2..94251d76b2 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -274,6 +274,11 @@ namespace {
     void WriteRelocationsFragment(const MCAssembler &Asm, MCDataFragment *F,
                                   const MCSectionData *SD);
 
+    bool IsFixupFullyResolved(const MCAssembler &Asm,
+                              const MCValue Target,
+                              bool IsPCRel,
+                              const MCFragment *DF) const;
+
     void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout);
   };
 
@@ -775,7 +780,7 @@ void ELFObjectWriterImpl::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
 
     WriteRelocationsFragment(Asm, F, &SD);
 
-    Asm.AddSectionToTheEnd(RelaSD, Layout);
+    Asm.AddSectionToTheEnd(*Writer, RelaSD, Layout);
   }
 }
 
@@ -873,11 +878,11 @@ void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm,
   // Symbol table
   F = new MCDataFragment(&SymtabSD);
   WriteSymbolTable(F, Asm, Layout, NumRegularSections);
-  Asm.AddSectionToTheEnd(SymtabSD, Layout);
+  Asm.AddSectionToTheEnd(*Writer, SymtabSD, Layout);
 
   F = new MCDataFragment(&StrtabSD);
   F->getContents().append(StringTable.begin(), StringTable.end());
-  Asm.AddSectionToTheEnd(StrtabSD, Layout);
+  Asm.AddSectionToTheEnd(*Writer, StrtabSD, Layout);
 
   F = new MCDataFragment(&ShstrtabSD);
 
@@ -903,7 +908,41 @@ void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm,
     F->getContents() += '\x00';
   }
 
-  Asm.AddSectionToTheEnd(ShstrtabSD, Layout);
+  Asm.AddSectionToTheEnd(*Writer, ShstrtabSD, Layout);
+}
+
+bool ELFObjectWriterImpl::IsFixupFullyResolved(const MCAssembler &Asm,
+                                               const MCValue Target,
+                                               bool IsPCRel,
+                                               const MCFragment *DF) const {
+  // If this is a PCrel relocation, find the section this fixup value is
+  // relative to.
+  const MCSection *BaseSection = 0;
+  if (IsPCRel) {
+    BaseSection = &DF->getParent()->getSection();
+    assert(BaseSection);
+  }
+
+  const MCSection *SectionA = 0;
+  const MCSymbol *SymbolA = 0;
+  if (const MCSymbolRefExpr *A = Target.getSymA()) {
+    SymbolA = &A->getSymbol();
+    SectionA = &SymbolA->getSection();
+  }
+
+  const MCSection *SectionB = 0;
+  if (const MCSymbolRefExpr *B = Target.getSymB()) {
+    SectionB = &B->getSymbol().getSection();
+  }
+
+  if (!BaseSection)
+    return SectionA == SectionB;
+
+  const MCSymbolData &DataA = Asm.getSymbolData(*SymbolA);
+  if (DataA.isExternal())
+    return false;
+
+  return !SectionB && BaseSection == SectionA;
 }
 
 void ELFObjectWriterImpl::WriteObject(const MCAssembler &Asm,
@@ -1064,6 +1103,14 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
                                                   Target, FixedValue);
 }
 
+bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
+                                           const MCValue Target,
+                                           bool IsPCRel,
+                                           const MCFragment *DF) const {
+  return ((ELFObjectWriterImpl*) Impl)->IsFixupFullyResolved(Asm, Target,
+                                                             IsPCRel, DF);
+}
+
 void ELFObjectWriter::WriteObject(const MCAssembler &Asm,
                                   const MCAsmLayout &Layout) {
   ((ELFObjectWriterImpl*) Impl)->WriteObject(Asm, Layout);