1 files changed, 50 insertions, 12 deletions

diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp
index c57b0d6..0098bea 100644
--- a/lib/MC/MachObjectWriter.cpp
+++ b/lib/MC/MachObjectWriter.cpp
@@ -10,24 +10,33 @@
 #include "llvm/MC/MCMachObjectWriter.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/Twine.h"
-#include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCAsmLayout.h"
+#include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/MC/MCMachOSymbolFlags.h"
 #include "llvm/MC/MCObjectWriter.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCSymbol.h"
-#include "llvm/MC/MCMachOSymbolFlags.h"
 #include "llvm/MC/MCValue.h"
 #include "llvm/Object/MachOFormat.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-
 #include <vector>
 using namespace llvm;
 using namespace llvm::object;
 
+void MachObjectWriter::reset() {
+  Relocations.clear();
+  IndirectSymBase.clear();
+  StringTable.clear();
+  LocalSymbolData.clear();
+  ExternalSymbolData.clear();
+  UndefinedSymbolData.clear();
+  MCObjectWriter::reset();
+}
+
 bool MachObjectWriter::
 doesSymbolRequireExternRelocation(const MCSymbolData *SD) {
   // Undefined symbols are always extern.
@@ -68,6 +77,11 @@ uint64_t MachObjectWriter::getSymbolAddress(const MCSymbolData* SD,
 
   // If this is a variable, then recursively evaluate now.
   if (S.isVariable()) {
+    if (const MCConstantExpr *C =
+          dyn_cast<const MCConstantExpr>(S.getVariableValue()))
+      return C->getValue();
+
+
     MCValue Target;
     if (!S.getVariableValue()->EvaluateAsRelocatable(Target, Layout))
       report_fatal_error("unable to evaluate offset for variable '" +
@@ -140,8 +154,8 @@ void MachObjectWriter::WriteHeader(unsigned NumLoadCommands,
 
 /// WriteSegmentLoadCommand - Write a segment load command.
 ///
-/// \arg NumSections - The number of sections in this segment.
-/// \arg SectionDataSize - The total size of the sections.
+/// \param NumSections The number of sections in this segment.
+/// \param SectionDataSize The total size of the sections.
 void MachObjectWriter::WriteSegmentLoadCommand(unsigned NumSections,
                                                uint64_t VMSize,
                                                uint64_t SectionDataStartOffset,
@@ -315,11 +329,7 @@ void MachObjectWriter::WriteNlist(MachSymbolData &MSD,
 
   // Compute the symbol address.
   if (Symbol.isDefined()) {
-    if (Symbol.isAbsolute()) {
-      Address = cast<MCConstantExpr>(Symbol.getVariableValue())->getValue();
-    } else {
-      Address = getSymbolAddress(&Data, Layout);
-    }
+    Address = getSymbolAddress(&Data, Layout);
   } else if (Data.isCommon()) {
     // Common symbols are encoded with the size in the address
     // field, and their alignment in the flags.
@@ -557,6 +567,26 @@ void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
   }
 }
 
+void MachObjectWriter::markAbsoluteVariableSymbols(MCAssembler &Asm,
+                                                   const MCAsmLayout &Layout) {
+  for (MCAssembler::symbol_iterator i = Asm.symbol_begin(),
+                                    e = Asm.symbol_end();
+      i != e; ++i) {
+    MCSymbolData &SD = *i;
+    if (!SD.getSymbol().isVariable())
+      continue;
+
+    // Is the variable is a symbol difference (SA - SB + C) expression,
+    // and neither symbol is external, mark the variable as absolute.
+    const MCExpr *Expr = SD.getSymbol().getVariableValue();
+    MCValue Value;
+    if (Expr->EvaluateAsRelocatable(Value, Layout)) {
+      if (Value.getSymA() && Value.getSymB())
+        const_cast<MCSymbol*>(&SD.getSymbol())->setAbsolute();
+    }
+  }
+}
+
 void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
                                                 const MCAsmLayout &Layout) {
   computeSectionAddresses(Asm, Layout);
@@ -564,6 +594,10 @@ void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
   // Create symbol data for any indirect symbols.
   BindIndirectSymbols(Asm);
 
+  // Mark symbol difference expressions in variables (from .set or = directives)
+  // as absolute.
+  markAbsoluteVariableSymbols(Asm, Layout);
+
   // Compute symbol table information and bind symbol indices.
   ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
                      UndefinedSymbolData);
@@ -795,8 +829,12 @@ void MachObjectWriter::WriteObject(MCAssembler &Asm,
          it = Asm.data_region_begin(), ie = Asm.data_region_end();
          it != ie; ++it) {
     const DataRegionData *Data = &(*it);
-    uint64_t Start = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start), Layout);
-    uint64_t End = getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End), Layout);
+    uint64_t Start =
+      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->Start),
+                       Layout);
+    uint64_t End =
+      getSymbolAddress(&Layout.getAssembler().getSymbolData(*Data->End),
+                       Layout);
     DEBUG(dbgs() << "data in code region-- kind: " << Data->Kind
                  << "  start: " << Start << "(" << Data->Start->getName() << ")"
                  << "  end: " << End << "(" << Data->End->getName() << ")"