MC/Mach-O: Update getSymbolAddress() to support evaluation of variables.

llvm-svn: 130522

Author: ddunbar

llvm/lib/MC/MachObjectWriter.cpp

@@ -121,6 +121,33 @@ class MachObjectWriter : public MCObjectWriter {
   }
   uint64_t getSymbolAddress(const MCSymbolData* SD,
                             const MCAsmLayout &Layout) const {
+    const MCSymbol &S = SD->getSymbol();
+
+    // If this is a variable, then recursively evaluate now.
+    if (S.isVariable()) {
+      MCValue Target;
+      if (!S.getVariableValue()->EvaluateAsRelocatable(Target, Layout))
+        report_fatal_error("unable to evaluate offset for variable '" +
+                           S.getName() + "'");
+
+      // Verify that any used symbols are defined.
+      if (Target.getSymA() && Target.getSymA()->getSymbol().isUndefined())
+        report_fatal_error("unable to evaluate offset to undefined symbol '" +
+                           Target.getSymA()->getSymbol().getName() + "'");
+      if (Target.getSymB() && Target.getSymB()->getSymbol().isUndefined())
+        report_fatal_error("unable to evaluate offset to undefined symbol '" +
+                           Target.getSymB()->getSymbol().getName() + "'");
+
+      uint64_t Address = Target.getConstant();
+      if (Target.getSymA())
+        Address += getSymbolAddress(&Layout.getAssembler().getSymbolData(
+                                      Target.getSymA()->getSymbol()), Layout);
+      if (Target.getSymB())
+        Address += getSymbolAddress(&Layout.getAssembler().getSymbolData(
+                                      Target.getSymB()->getSymbol()), Layout);
+      return Address;
+    }
+
     return getSectionAddress(SD->getFragment()->getParent()) +
       Layout.getSymbolOffset(SD);
   }