1 files changed, 17 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
index c90e41ca724..e7713f34321 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -93,6 +93,23 @@ public:
 
     assert(Fixup.getOffset() + Size <= DataSize &&
            "Invalid fixup offset!");
+
+    // Check that the upper bits are either all 0 or all 1's
+    switch (Size) {
+    case 1: 
+      assert((isInt<8>(Value) || isUInt<8>(Value)) && 
+             "Value does not fit in a 1Byte Reloc");
+      break;
+    case 2: 
+      assert((isInt<16>(Value) || isUInt<16>(Value)) && 
+             "Value does not fit in a 2Byte Reloc");
+      break;
+    case 4:
+      assert((isInt<32>(Value) || isUInt<32>(Value)) && 
+             "Value does not fit in a 4Byte Reloc");
+      break;
+    }
+
     for (unsigned i = 0; i != Size; ++i)
       Data[Fixup.getOffset() + i] = uint8_t(Value >> (i * 8));
   }