Fix 1 << 31

[eax]

Summary

1 << 31 is not legal in C++ prior to C++14

[t.p.northover]

Hi Eitan,

Thanks for looking at this, we should definitely get rid of UB wherever we can. There's a slight problem with the patch though, unfortunately.

Cheers.

Tim.

include/llvm-c/Core.h

162

This one's apparently also undefined in C ("enumeration constant shall be an integer constant expression that has a value representable as an int").

include/llvm-c/Core.h

     LLVMStackAlignment = 7<<26,
     LLVMReturnsTwice = 1 << 29,
     LLVMUWTable = 1 << 30,
-    LLVMNonLazyBind = 1 << 31
+    LLVMNonLazyBind = 1U << 31
 
     /* FIXME: These attributes are currently not included in the C API as
        a temporary measure until the API/ABI impact to the C API is understood

include/llvm/CodeGen/MachORelocation.h

   public:      
     uint32_t getPackedFields() const {
       if (r_scattered)
-        return (1 << 31) | (r_pcrel << 30) | ((r_length & 3) << 28) | 
+        return (1U << 31) | (r_pcrel << 30) | ((r_length & 3) << 28) |
           ((r_type & 15) << 24) | (r_address & 0x00FFFFFF);
       else
         return (r_symbolnum << 8) | (r_pcrel << 7) | ((r_length & 3) << 5) |

lib/CodeGen/SelectionDAG/SelectionDAG.cpp

     llvm::ComputeMaskedBits(const_cast<GlobalValue*>(GV), KnownZero, KnownOne,
                             TLI->getDataLayout());
     unsigned AlignBits = KnownZero.countTrailingOnes();
-    unsigned Align = AlignBits ? 1 << std::min(31U, AlignBits) : 0;
+    unsigned Align = AlignBits ? 1U << std::min(31U, AlignBits) : 0;
     if (Align)
       return MinAlign(Align, GVOffset);
   }
 
   // If this is a direct reference to a stack slot, use information about the
   // stack slot's alignment.
-  int FrameIdx = 1 << 31;
+  int FrameIdx = 1U << 31;
   int64_t FrameOffset = 0;
   if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Ptr)) {
     FrameIdx = FI->getIndex();

     FrameOffset = Ptr.getConstantOperandVal(1);
   }
 
-  if (FrameIdx != (1 << 31)) {
+  if (FrameIdx != (1U << 31)) {
     const MachineFrameInfo &MFI = *getMachineFunction().getFrameInfo();
     unsigned FIInfoAlign = MinAlign(MFI.getObjectAlignment(FrameIdx),
                                     FrameOffset);