Fixed a crash in llvm-mc for Mach-O when a symbol difference expression uses a

[oota-llvm.git] / lib / MC / MCObjectWriter.cpp

diff --git a/lib/MC/MCObjectWriter.cpp b/lib/MC/MCObjectWriter.cpp
index f7a790410cdfe6822e54a2341c5388df297b59f9..030f24793c55b547e761d9f2757b6ff604dcd39a 100644 (file)
--- a/lib/MC/MCObjectWriter.cpp
+++ b/lib/MC/MCObjectWriter.cpp
@@ -33,14 +33,22 @@ void MCObjectWriter::EncodeSLEB128(int64_t Value, raw_ostream &OS) {
 }
 
 /// Utility function to encode a ULEB128 value.
-void MCObjectWriter::EncodeULEB128(uint64_t Value, raw_ostream &OS) {
+void MCObjectWriter::EncodeULEB128(uint64_t Value, raw_ostream &OS,
+                                   unsigned Padding) {
   do {
     uint8_t Byte = Value & 0x7f;
     Value >>= 7;
-    if (Value != 0)
+    if (Value != 0 || Padding != 0)
       Byte |= 0x80; // Mark this byte that that more bytes will follow.
     OS << char(Byte);
   } while (Value != 0);
+
+  // Pad with 0x80 and emit a null byte at the end.
+  if (Padding != 0) {
+    for (; Padding != 1; --Padding)
+      OS << '\x80';
+    OS << '\x00';
+  }
 }
 
 bool
@@ -60,9 +68,23 @@ MCObjectWriter::IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
 
   const MCSymbolData &DataA = Asm.getSymbolData(SA);
   const MCSymbolData &DataB = Asm.getSymbolData(SB);
+  if(!DataA.getFragment() || !DataB.getFragment())
+    return false;
 
   return IsSymbolRefDifferenceFullyResolvedImpl(Asm, DataA,
                                                 *DataB.getFragment(),
                                                 InSet,
                                                 false);
 }
+
+bool
+MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+                                                      const MCSymbolData &DataA,
+                                                      const MCFragment &FB,
+                                                      bool InSet,
+                                                      bool IsPCRel) const {
+  const MCSection &SecA = DataA.getSymbol().AliasedSymbol().getSection();
+  const MCSection &SecB = FB.getParent()->getSection();
+  // On ELF and COFF  A - B is absolute if A and B are in the same section.
+  return &SecA == &SecB;
+}