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 d117e82b8a1ff28bb7369a36df20fb3396727c4e..030f24793c55b547e761d9f2757b6ff604dcd39a 100644 (file)
--- a/lib/MC/MCObjectWriter.cpp
+++ b/lib/MC/MCObjectWriter.cpp
@@ -7,9 +7,84 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSymbol.h"
 
 using namespace llvm;
 
 MCObjectWriter::~MCObjectWriter() {
 }
+
+/// Utility function to encode a SLEB128 value.
+void MCObjectWriter::EncodeSLEB128(int64_t Value, raw_ostream &OS) {
+  bool More;
+  do {
+    uint8_t Byte = Value & 0x7f;
+    // NOTE: this assumes that this signed shift is an arithmetic right shift.
+    Value >>= 7;
+    More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
+              ((Value == -1) && ((Byte & 0x40) != 0))));
+    if (More)
+      Byte |= 0x80; // Mark this byte that that more bytes will follow.
+    OS << char(Byte);
+  } while (More);
+}
+
+/// Utility function to encode a ULEB128 value.
+void MCObjectWriter::EncodeULEB128(uint64_t Value, raw_ostream &OS,
+                                   unsigned Padding) {
+  do {
+    uint8_t Byte = Value & 0x7f;
+    Value >>= 7;
+    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
+MCObjectWriter::IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
+                                                   const MCSymbolRefExpr *A,
+                                                   const MCSymbolRefExpr *B,
+                                                   bool InSet) const {
+  // Modified symbol references cannot be resolved.
+  if (A->getKind() != MCSymbolRefExpr::VK_None ||
+      B->getKind() != MCSymbolRefExpr::VK_None)
+    return false;
+
+  const MCSymbol &SA = A->getSymbol();
+  const MCSymbol &SB = B->getSymbol();
+  if (SA.AliasedSymbol().isUndefined() || SB.AliasedSymbol().isUndefined())
+    return false;
+
+  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;
+}